Partial List of Superconductors to Build Out

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Found a collection in a few different papers. There might be a single long list somewhere on the internet nothing came up for it.

I'm looking at building these out with just picture diagrams from Miles Mathis' atomic structures in Nevyn's Periodic Table.

Partial List of Superconductors
https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=(SnPb0.5ln0.5)Ba4Tm6Cu8O22
#   -    Formula                                               Link to Nevyn's Molecular Bonding Language Engine      
1  -     (SnPb0.5ln0.5)Ba4Tm6Cu8O22  -     (SnPb0.5ln0.5)Ba4Tm6Cu8O22
2  -     (SnPbO.5lnO.5)Ba4Tm5Cu7O20  -     (SnPbO.5lnO.5)Ba4Tm5Cu7O20
3  -     (SnTiO.5Pb0.5)Ba4Tm3Cu5O16  -     (SnTiO.5Pb0.5)Ba4Tm3Cu5O16
4  -     (Ti4Ba)Ba2Mg2Cu7O13  -     (Ti4Ba)Ba2Mg2Cu7O13
5  -     (Ti4Ba)Ba2MgCu8O13  -     (Ti4Ba)Ba2MgCu8O13
6  -     (Ti4Ba)Ba4Ca2Cu10O2  -     (Ti4Ba)Ba4Ca2Cu10O2
7  -     (Ti4Ba)Ba4Ca2Cu7O13  -     (Ti4Ba)Ba4Ca2Cu7O13
8  -     (Ti4Pb)Ba2Mg2Cu7O13  -     (Ti4Pb)Ba2Mg2Cu7O13
9  -     (Ti4Pb)Ba2MqCu8O13  -     (Ti4Pb)Ba2MqCu8O13
10  -     (Ti5Pb2)Ba2Mg2Cu9O17  -     (Ti5Pb2)Ba2Mg2Cu9O17
11  -     (TiCd0.5ln0.5)Ba4TmCaCu4O2  -     (TiCd0.5ln0.5)Ba4TmCaCu4O2
12  -     (TMTSF)2PF6  -     (TMTSF)2PF6
13  -     BaTi2Pb2O  -     BaTi2Pb2O
14  -     AuIn2O3  -     AuIn2O3
15  -     AuTe2Se4/3  -     AuTe2Se4/3
16  -     Ba12ZnO13  -     Ba12ZnO13
17  -     BaFe1.8Co0.2As2  -     BaFe1.8Co0.2As2
18  -     BaSr2CaCu4O8  -     BaSr2CaCu4O8
19  -     BaTi2Bi2O  -     BaTi2Bi2O
20  -     BaTi2Sb2O  -     BaTi2Sb2O
21  -     BaTiO  -     BaTiO
22  -     Bi2Sr2CaCu2O  -     Bi2Sr2CaCu2O
23  -     Bi2Sr2CaCu2O8  -     Bi2Sr2CaCu2O8
24  -     Bi2Sr2TeCu3O8  -     Bi2Sr2TeCu3O8
25  -     BiPbSr2Ca2Cu3O10  -     BiPbSr2Ca2Cu3O10
26  -     BiS2  -     BiS2
27  -     BiSnBa4TmCaCu4O14  -     BiSnBa4TmCaCu4O14
28  -     BMg2O2  -     BMg2O2
29  -     CaKFe4As4  -     CaKFe4As4
30  -     Cd2CaCu3O6  -     Cd2CaCu3O6
31  -     Cd3CaCu4O8  -     Cd3CaCu4O8
32  -     CdCaCu2O4  -     CdCaCu2O4
33  -     CdCaMg2O2  -     CdCaMg2O2
34  -     CdNbBa9Cu10O20  -     CdNbBa9Cu10O20
35  -     CdSMgos  -     CdSMgos
36  -     Cu2M9O3  -     Cu2M9O3
37  -     Cu3MgO4  -     Cu3MgO4
38  -     CuMgO2  -     CuMgO2
--   -       DyBa2Cu3O7   -     DyBa2Cu3O7
39  -     FePSr2ScO3  -     FePSr2ScO3
40  -     FeSe  -     FeSe
41  -     Ga2Sr4Tm2CaCu5O2  -     Ga2Sr4Tm2CaCu5O2
42  -     Ga2Sr4Y2CaCu5O2  -     Ga2Sr4Y2CaCu5O2
43  -     GaBa2O2  -     GaBa2O2
44  -     GaSr2(CaO5TmO.5)Cu2O7  -     GaSr2(CaO5TmO.5)Cu2O7
45  -     HgBaCaCu  -     HgBaCaCu
46  -     HgBaCaCuO  -     HgBaCaCuO
47  -     In4Sn2Ba2MnCu7O14  -     In4Sn2Ba2MnCu7O14
48  -     In4Sn2Ba2TiCu7O14  -     In4Sn2Ba2TiCu7O14
49  -     In5Ba4SiCu8O16  -     In5Ba4SiCu8O16
50  -     In5Sn2Ba2SiCu8O16  -     In5Sn2Ba2SiCu8O16
51  -     In6Sn2Ba2SiCu9O13  -     In6Sn2Ba2SiCu9O13
52  -     In7Sn2Ba2SiCu10O20  -     In7Sn2Ba2SiCu10O20
53  -     LaOFeAs  -     LaOFeAs
54  -     LaBaCa2Cu4O2  -     LaBaCa2Cu4O2
55  -     LBCO  -     LBCO
56  -     LnFeAsOF  -     LnFeAsOF
57  -     MnTiO3  -     MnTiO3
58  -     MoS28  -     MoS28
59  -     NbBa9Cu10O20  -     NbBa9Cu10O20
60  -     NbSe27  -     NbSe27
61  -     NbTi  -     NbTi
62  -     NdO07F03BiS2  -     NdO07F03BiS2
63  -     Pb3MgOS  -     Pb3MgOS
64  -     Pb3Sn3Sr8Ca4Cu10O30  -     Pb3Sn3Sr8Ca4Cu10O30
65  -     Pb3Sr4Ca3Cu6O2  -     Pb3Sr4Ca3Cu6O2
66  -     PCCO  -     PCCO
67  -     PbGaSr4YCaCu4O2  -     PbGaSr4YCaCu4O2
68  -     Pr2CeCuO4  -     Pr2CeCuO4
69  -     ScBa2O2  -     ScBa2O2
70  -     SmFeAsO1  -     SmFeAsO1
71  -     Sn1.4ln0.6Ba4Tm5Cu7O20  -     Sn1.4ln0.6Ba4Tm5Cu7O20
72  -     Sn10SbTe4Ba2MnCu16O32  -     Sn10SbTe4Ba2MnCu16O32
73  -     Sn10ShTe9Ba2MnCu21042  -     Sn10ShTe9Ba2MnCu21042
74  -     Sn11SbTe10Ba2VMg23O46  -     Sn11SbTe10Ba2VMg23O46
75  -     Sn11SbTe10Ba2VZMg22O46  -     Sn11SbTe10Ba2VZMg22O46
76  -     Sn12SbTe11Ba2WMg24O50  -     Sn12SbTe11Ba2WMg24O50
77  -     Sn3Ba4Ca2Cu7O2  -     Sn3Ba4Ca2Cu7O2
78  -     Sn3Ba4Im3Cu6O2  -     Sn3Ba4Im3Cu6O2
79  -     Sn3Ba4Y2Cu5O2  -     Sn3Ba4Y2Cu5O2
80  -     Sn3BaBCa4Cu11O2  -     Sn3BaBCa4Cu11O2
81  -     Sn3Sb3Ba2MnCu7O14  -     Sn3Sb3Ba2MnCu7O14
82  -     Sn4Ba4(Tm2Y)Cu7O18  -     Sn4Ba4(Tm2Y)Cu7O18
83  -     Sn4Ba4(YTm)Cu6O16  -     Sn4Ba4(YTm)Cu6O16
84  -     Sn4Ba41m2CaCu7O2  -     Sn4Ba41m2CaCu7O2
85  -     Sn4Ba4CaTmCu4O2  -     Sn4Ba4CaTmCu4O2
86  -     Sn4Ba4Tm3Cu7O2  -     Sn4Ba4Tm3Cu7O2
87  -     Sn4Sb4Ba2MnMg9O18  -     Sn4Sb4Ba2MnMg9O18
88  -     Sn4Te4Ba2MnMg9O18  -     Sn4Te4Ba2MnMg9O18
89  -     Sn5InBa4Ca2Cu11O2  -     Sn5InBa4Ca2Cu11O2
90  -     Sn5lnBa4Ca2Cu10O2  -     Sn5lnBa4Ca2Cu10O2
91  -     Sn5SbSBa2MnCM  -     Sn5SbSBa2MnCM
92  -     Sn5Te5Ba2VMg11O22  -     Sn5Te5Ba2VMg11O22
93  -     Sn6Ba4Ca2Cu10O2  -     Sn6Ba4Ca2Cu10O2
94  -     Sn6Sb6Ba2MnCu13O26  -     Sn6Sb6Ba2MnCu13O26
95  -     Sn7Te7Ba2MnCu15030  -     Sn7Te7Ba2MnCu15030
96  -     Sn8SbTe4Ba2MnCu14O28  -     Sn8SbTe4Ba2MnCu14O28
97  -     Sn9SbTe3Ba2MnCu14O28  -     Sn9SbTe3Ba2MnCu14O28
98  -     Sn9SbTe4Ba2MnCu15O30  -     Sn9SbTe4Ba2MnCu15O30
99  -     Sn9SbTe8Ba2MnCu19O38  -     Sn9SbTe8Ba2MnCu19O38
100  -     Sn9Te3Ba2MnCu13O26  -     Sn9Te3Ba2MnCu13O26
101  -     Sn9SbTe7Ba2MnCu17O34  -     Sn9ShTe7Ba2MnCu17O34
102  -     Sn9SbTe6Ba2MnCu15030  -     Sn9ShTe6Ba2MnCu15030
103  -     Sr2ScFePO3  -     Sr2ScFePO3
104  -     Sr2CaO3  -     Sr2CaO3
105  -     Sr3CaO4  -     Sr3CaO4
106  -     Sr7Ti6O19  -     Sr7Ti6O19
107  -     SrAuSi3  -     SrAuSi3
108  -     SrCaMg2O2  -     SrCaMg2O2
109  -     SrCaO2  -     SrCaO2
110  -     TaBa9Cu10O20  -     TaBa9Cu10O20
111  -     TaSi2O2  -     TaSi2O2
112  -     TeBa10Cu11O22  -     TeBa10Cu11O22
113  -     TeBa3Cu4O2  -     TeBa3Cu4O2
114  -     TeBa7Cu8O17  -     TeBa7Cu8O17
115  -     TeBa7Cu8O17  -     TeBa7Cu8O17
116  -     TeCaBa4Cu6O14  -     TeCaBa4Cu6O14
117  -     ThCr2Si2  -     ThCr2Si2
118  -     Ti2Ba2TeCu3O8  -     Ti2Ba2TeCu3O8
119  -     Ti2Ba2YCu2O6  -     Ti2Ba2YCu2O6
120  -     Ti5Ba4SiCu8O16  -     Ti5Ba4SiCu8O16
121  -     Ti5Pb2Ba2Mg2.SCu8.SO17  -     Ti5Pb2Ba2Mg2.SCu8.SO17
122  -     Ti5Pb2Ba2MgCu10O17  -     Ti5Pb2Ba2MgCu10O17
123  -     Ti5Pb2Ba2Si2.5Cu8.5O17  -     Ti5Pb2Ba2Si2.5Cu8.5O17
124  -     Ti5Pb2Ba2SiCu8O16  -     Ti5Pb2Ba2SiCu8O16
125  -     Ti5Sn2Ba2SiCu8O16  -     Ti5Sn2Ba2SiCu8O16
126  -     Ti7Sn2Ba2MnCu10O20  -     Ti7Sn2Ba2MnCu10O20
127  -     Ti7Sn2Ba2SiCu10O20  -     Ti7Sn2Ba2SiCu10O20
128  -     Ti7Sn2Ba2TiCu10O20  -     Ti7Sn2Ba2TiCu10O20
129  -     TiBa2O2  -     TiBa2O2
130  -     TiBa7Cu8O16  -     TiBa7Cu8O16
131  -     TiBa7M98O16  -     TiBa7M98O16
132  -     TiBa9Cu10O20  -     TiBa9Cu10O20
133  -     TiMg2O2  -     TiMg2O2
134  -     Ti5Ba4Ca2Cu10O2  -     Ti5Ba4Ca2Cu10O2
135  -     Ti6Ba4SiCu9O18  -     Ti6Ba4SiCu9O18
136  -     TiBa4TmCaCu5O2  -     TiBa4TmCaCu5O2
137  -     TiSnBa4Y2Cu4O2  -     TiSnBa4Y2Cu4O2
138  -     Tm2SiO2  -     Tm2SiO2
139  -     Tm2YO4.5  -     Tm2YO4.5
140  -     Tm3YO6  -     Tm3YO6
141  -     TmYO3  -     TmYO3
142  -     VBa9Cu10O20  -     VBa9Cu10O20
143  -     Y2SnBa4Cu5O2  -     Y2SnBa4Cu5O2
144  -     Y2Ba1IJCu12O25  -     Y2Ba1IJCu12025
145  -     Y2BaSCu7O2  -     Y2BaSCu7O2
146  -     Y2BaSCu8O17  -     Y2BaSCu8O17
147  -     Y2CaBa4Cu7O16  -     Y2CaBa4Cu7O16
148  -     Y3Ba5Cu8O2  -     Y3Ba5Cu8O2
149  -     Y3CaBa4Cu8O18  -     Y3CaBa4Cu8O18
150  -     Y3Fe2(FeO4)3  -     Y3Fe2(FeO4)3
151  -     YBa2Cu3O7  -     YBa2Cu3O7
152  -     YBa2Cu3O7  -     YBa2Cu3O7
153  -     YBa2Mg3O2  -     YBa2Mg3O2
154  -     YBa2O2  -     YBa2O2
155  -     Y3Ba4Cu7O16  -     Y3Ba4Cu7O16
156  -     YCaBa3Cu5O11  -     YCaBa3Cu5O11
157  -     Y0.5Gd0.SBa2Cu3O7  -     YO.5Gd0.5Ba2Cu3O7
158  -     Y0.5Lu0.SBa2Cu3O7  -     YO.5Lu0.5Ba2Cu3O7
159  -     YPtBi  -     YPtBi
160  -     YSrCa2Cu4O8  -     YSrCa2Cu4O8
161  -     YTm0.SBa2Cu307  -     YTm0.SBa2Cu307
162  -     Zn2MgO3  -     Zn2MgO3
163  -     Zn3MgO4  -     Zn3MgO4
164  -     ZnMgO2  -     ZnMgO2
165  -     ZrBa9Cu10O20  -     ZrBa9Cu10O20
166  -     ZrNCl6  -     ZrNCl6
167  -     ZrTe5  -     ZrTe5
168  -      C6Li3Ca2          -       C6Li3Ca2
169  -      Nb3Ge              -       Nb3Ge
170  -      LiFeAs              -       LiFeAs
171  -      NaFeAs             -      NaFeAs
172  -      CeFeAsOF         -       CeFeAsOF
173  -      ErFeAsO           -       ErFeAsO
174  -      NdFeAsF           -       NdFeAsF
175  -      GdFeAsO          -       GdFeAsO
176  -      SrSmFeAsF       -       SrSmFeAsF

(note the MBL from Nevyn no longer functions. The site is down. Try creating Molecules manually by selecting Elements at this link: http://www.users.on.net/~Nevyn/science/physics/AtomicWebViewer

List from SuperConductors.org

http://www.superconductors.org/50plus.htm

Superconductors.org wrote:Planar Weight Disparity:  Essential to HTSC?
Over 140 New Superconductors Lend Strong Support

15 October 2011
Last revision: Sept. 2017
Superconductors.ORG

      Superconductors.ORG herein reports more than 140 new superconductors have now been discovered since planar weight disparity (PWD) was found to be a key component of high temperature superconductivity in 2005 (list at page bottom). This suggests strongly that PWD is not just a Tc-enhancement mechanism, but an essential component of high temperature superconductivity in the copper-oxides.

Wikipedia's List
http://en.wikipedia.org/wiki/List_of_superconductors
--------
The table below shows some of the parameters of common superconductors of simple structure. X:Y means material X doped with element Y, TC is the highest reported transition temperature in kelvin and HC is a critical magnetic field in tesla. "BCS" means whether or not the superconductivity is explained within the BCS theory.

No Element
1 Al
2 Cd
3 Diamond:B
4 Ga
5 Hf
6 α-Hg
7 β-Hg
8 In
9 Ir
10 α-La
11 β-La
12 Mo
13 Nb
14 Os
15 Pa
16 Pb
17 Re
18 Ru
19 Si:B
20 Sn
21 Ta
22 Tc
23 α-Th
24 Ti
25 Tl
26 α-U
27 β-U
28 V
29 α-W
30 β-W
31 Zn
32 Zr
33 Ba8Si46
34 C6Ca
35 C6Li3Ca2
36 C8K
37 C8KHg
38 C6K
39 C3K
40 C3Li
41 C2Li
42 C3Na
43 C2Na
44 C8Rb
45 C6Sr
46 C6Yb
47 C60Cs2Rb
48 C60K3
49 C60RbX
50 43135
51 InN
52 In2O3
53 LaB6
54 MgB2
55 Nb3Al
56 Nb3Ge
57 NbO
58 NbN
59 Nb3Sn
60 NbTi
61 SiC:B
62 SiC:Al
63 TiN
64 YB6
65 ZrN
66 ZrB12

Yttrium iron garnet
https://en.wikipedia.org/wiki/Yttrium_iron_garnet

I've been thinking about building molecules and I had a brief thought about specifying a molecular language. Something that allows the user to easily define the atoms and bonds in a molecule textually and also easy enough for me to then build a molecule from it. That would not work for all molecules, because some of them have special bonds, but it could work for these types of molecules which are fairly straight structures. Although, looking at those lists leads me to think that some of them are not so straight.

It could be as simple as B-F-Ar-F-Ar-P, for example. Maybe '-' means on the north/south axis and we could use '+' for the carousel bonds. They do get tricky because you can have up to 4 bonds at the carousel level. Maybe use parentheses to group into sub-structures when there are multiple complex parts to the molecule. I could use square brackets to denote multiple bonds to the preceding atom. For example to specify FeO3 you might use: F[-O,+O,+O] to connect one Oxygen to the top of Iron and the other 2 to the carousel level.

I initially dropped this idea because it couldn't handle very complex bonds without a very complex language, but it might be quite good for the simple things. If anyone has an opinion about it, please speak up and I will see if this is worth investigating. I like the idea of us being able to quickly generate structures for our discussions. This type of language could lead to an image server where you specify the molecule on the URL and it generates an image of it for you as opposed to a dedicated building environment like I have been thinking about. Of course, I want both so it isn't a one or the other type of situation but I might be able to get something operational a bit quicker.

I like your notation Nevyn it is very clear.  

I was correcting the list above changing "Z" to "2" and noticed a lot of Ba2 in many of these molecules.

Here's the first post from Miles' Solid Light paper:

http://www.milesmathis.com/solidlight.pdf

Miles Mathis wrote:
In closing, I will answer one final question. Above I have said that the Meissner Effect is caused by
loss of the equatorial channel, and thereby the magnetic field. But if we lose the nuclear spin, we
should lose all conduction, shouldn't we? Since the spin is what caused charge to move through in the
first place, loss of spin should cause not only a loss of the magnetic field, but the electrical field as
well. Loss of spin should cause total loss of field potentials around the nucleus, which would negate
through charge just as much as equatorial charge. If the electrical field is lost, how can we have
superconduction?

Well, in a sense, we don't. Superconduction turns out to be a bit of a misnomer. Without nuclear spin,
the nucleus is no longer conducting at all, rigorously. It is only continuing to provide a path, given by
the nuclear structure, but the nuclear vortices are gone. The nucleus is no longer driving charge
through, it is now only allowing charge through. The driving force of the conduction must be supplied
by the incoming current itself. Remember, a superconductor is providing no resistance to a given
charge stream or ion stream. But we have to supply the current from outside. A superconductor can't
create its own current from an unstructured external field, as a normal conductor can. A
superconductor can only provide a zero-resistant path for a pre-existing structured field.

Wikipedia style coverage of the History of Superconductors (explains BCS theory). Miles pretty much trashes this material in the Solid Light paper:
http://www.superconductors.org/history.htm

HgBaCaCuO (Oxide version)
http://www.freepatentsonline.com/5858926.html

Notes:

The reason Russian compounds didn't work, it was speculated, was that the charge of the copper was too small. Jean Tholence explained to me that it is an empirical rule of thumb that the charge of the copper must be around 2.3 to have superconductivity. The first idea was to reduce yttrium, to make HgBa2CuO, which was found to be superconducting at 98 Kelvin. The second idea was to replace yttrium with calcium to raise the valence of the copper. Introducing calcium gave a new family of mercury compounds. The compounds are made up of mercury, barium, calcium, and copper oxides of the general form HgBa2Ca"-'Cu"O, where n=l, 2, 3. This yields the following shorthand, Hg-1201, Hg-1212, and Hg-1223, denoting the number of calcium atoms and copper oxide layers in the compounds. The latter two were found to be superconducting at 128 K and 135 K, which was confirmed by a research team in Zurich. These are the three mercury compounds that have been isolated and studied so far, although others are known to exist. "We now have phases with Hg-1234, Hg-1245," Tholence told me, "but up to now the Tc is not optimized. " For compounds with higher numbers of copper-oxygen layers, the Tc seems to decrease somewhat. For example, the phase Hg-1256 could have a Tc,around 100 K. As a group, these mercury compounds lead the pack of other superconductors with the highest Tc of any copperoxide layered compound of two or three layers. James Jorgensen, a researcher at Argonne National Laboratory in Illinois, who has been following ithis work with interest, observes that "the remarkable thing in these new compounds is that their structures are really very simple, simpler than the thallium and bismuth structures that previously held the record for the highest critical temperatures. "

(Note this is just an old link I found at this site with this paper cited. )
http://www.larouchepub.com/eiw/public/1994/eirv21n19-19940506/eirv21n19-19940506_020-research_advances_into_mercury_c.pdf
-----------
HgBaCaCu

I've given it a bit more thought and I think I can simplify the language while still allowing some complex structures to be defined.

The language is based on element chains which are north/south bonds denoted by the '-' bond operator. They are specified from bottom to top.
e.g. The above structure would be 'K-Hg-Ba-Cu'.

I removed the need for the '+' bonding operator by denoting carousel bonds inside of a comma separated list surrounded by '[' and ']'.
e.g. Fe[-O,-F]-C would create an Iron atom with an Oxygen atom bonded to the east and a Fluorine in the west carousel position '[-O,-F]' and Carbon bonded to the north position.

Each of the carousel items can be an element chain itself.
e.g. Fe[-O-H,-O-H]

The list is in the following order: east, west, front, back. If you don't want to use a certain position, then you can use the null operator '_'.
e.g. Fe[_,-F]-C would not have any atom in the carousel east position but has a Fluorine in the west.

Carousel atoms are turned 90° so that their bottom hook is bonded to the carousel of the preceding atom. I may use another bond operator to stop the turning and let things bond carousel to carousel. I'm not sure if that is needed at the moment. We might also have to specify whether we want to bond to the bottom or the top of the atom. We might need that in general, actually. I might introduce a flipping operator '!'.
e.g. !K-Hg-Ba-!Cu would cause the K and Cu atoms to be flipped 180°.

You can multiply part of a chain using the '(' and ')' operators followed by the number of times you want it repeated.
e.g. K-Hg-(Ba-Fe)3-P would expand into K-Hg-Ba-Fe-Ba-Fe-Ba-Fe-P.

That should allow some fairly complex molecules but would not be very good for big structures like the building blocks of DNA. I'll have a play with it and see how it goes.

Sounds like a good approach Nevyn. I'll try to flesh out a few this way and post the code next to each structure.

Quick note on ZrTe5:

The scientists found that (1) the appearance of superconductivity at the critical pressure is accompanied by the complete suppression of the high temperature resistance anomaly around 128 K, showing a structural transition from the Cmcm to C2/m space group, and (2) that at pressures above 21.2 GPa, a second superconducting phase with P-1 space group structure manifests and coexists with the original C2/m. (In mathematics and physics, a space group is the symmetry group of a configuration in space, usually in three dimensions.) "The superconductivity often appears in compounds which are close to a structural, magnetic, or electronic instability (as Miles has pointed out...) . More recent investigations have revealed that the high temperature resistance anomaly around 128 K is caused by temperature induced Lifshitz transition, in which the Fermi surface undergoes a change in topology and a drastic change in the electronic density of states." In their study, the team demonstrated that the appearance of superconductivity at the critical pressure is accompanied by the complete suppression of the resistance anomaly and a structural transition indicates that both electronic and structural instabilities are responsible for the observed superconductivity.

https://phys.org/news/2016-03-cool-pressure-superconductivity-3d-dirac.html

Related:

Scientists pinpoint energy flowing through vibrations in superconducting crystals

Manipulating the flow of energy through superconductors could radically transform technology, perhaps leading to applications such as ultra-fast, highly efficient quantum computers. But these subtle dynamics—including heat dispersion—play out with absurd speed across dizzying subatomic structures.

Now, scientists have tracked never-before-seen interactions between electrons and the crystal lattice structure of copper-oxide superconductors. The collaboration, led by scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, achieved measurement precision faster than one trillionth of one second through a groundbreaking combination of experimental techniques.

"This breakthrough offers direct, fundamental insight into the puzzling characteristics of these remarkable materials," said Brookhaven Lab scientist Yimei Zhu, who led the research. "We already had evidence of how lattice vibrations impact electron activity and disperse heat, but it was all through deduction. Now, finally, we can see it directly."

The results, published April 27 in the journal Science Advances, could advance research into powerful, fleeting phenomena found in copper oxides—including high-temperature superconductivity—and help scientists engineer new, better-performing materials.

"We found a nuanced atomic landscape, where certain high-frequency, 'hot' vibrations within the superconductor rapidly absorb energy from electrons and increase in intensity," said first author Tatiana Konstantinova, a Ph.D. student at Stony Brook University doing her thesis work at Brookhaven Lab. "Other sections of the lattice, however, were slow to react. Seeing this kind of tiered interaction transforms our understanding of copper oxides."

Scientists used ultra-fast electron diffraction and photoemission spectroscopy to observe changes in electron energy and momentum as well as fluctuations in the atomic structure.

Other collaborating institutions include SLAC National Accelerator Laboratory, North Carolina State University, Georgetown University, and the University of Duisburg-Essen in Germany.

Vibrations through a crystalline tree

The team chose Bi2Sr2CaCu2O8, a well-known superconducting copper oxide that exhibits the strong interactions central to the study. Even at temperatures close to absolute zero, the crystalline atomic lattice vibrates and very slight pulses of energy can cause the vibrations to increase in amplitude.

"These atomic vibrations are regimented and discrete, meaning they divide across specific frequencies," Zhu said. "We call vibrations with specific frequencies 'phonons,' and their interactions with flowing electrons were our target."

(more at link... https://phys.org/news/2018-04-scientists-energy-vibrations-superconducting-crystals.html  )

---------

Strained materials make cooler superconductors
April 24, 2018 by Sam Million-Weaver, University of Wisconsin-Madison


"Strain is one of the knobs we can turn to create materials with desirable properties, so it is important to learn to manipulate its effects," says Dane Morgan, the Harvey D. Spangler Professor of materials science and engineering at UW-Madison and a senior author on the paper. "These findings might also help explain some puzzling results in strained materials."
...
"The prevailing opinion has been that strain makes it thermodynamically easier for oxygen defects that destroy the superconducting properties to form in the material, but we have shown that differences in the kinetic time scales of oxygen-defect formation between tensile and compressive strain is a key mechanism," says Ryan Jacobs, a staff scientist in Morgan's laboratory and a co-first author on the paper.

Oxygen defects are important because the amount of oxygen contained within a material can alter its critical temperature. The most obvious idea was that strain might impact properties by adjusting how much energy is needed for oxygen defects to appear.

(more at link... https://phys.org/news/2018-04-strained-materials-cooler-superconductors.html  )

...


Method enables material to carry more electrical current without resistance at a higher temperature
October 6, 2016, Brookhaven National Laboratory

"Some ions or energies may cause large enough damage to interfere with superconductivity, while others may not produce any effect at all," explained coauthor Toshinori Ozaki, a former scientist in Brookhaven Lab's Advanced Energy Materials Group who is now a faculty member at Japan's Kwansei Gakuin University. "So we run simulations to figure out what combination should produce the optimal defect—one that can hold down the magnetic vortices without negatively impacting the material's superconducting properties."

In the case of the iron-based material the team studied, low-energy protons did the trick. Using electron microscopes, the scientists took images of the thin films (about 100 nanometers thick) of the material they prepared, before and after they hit the films with low-energy protons.

"Throughout the irradiated films, we saw individual chains of defects created by the collisions between the incident ions and nucleus that broke the perfect atomic order, causing the lattice to locally compress or stretch out," said coauthor Lijun Wu, a materials scientist at Brookhaven who led the microscopy work.

(more at link... https://phys.org/news/2016-10-method-enables-material-electrical-current.html  )

----------

A different spin on superconductivity—Unusual particle interactions open up new possibilities in exotic materials
April 7, 2018, University of Maryland

Finding that YPtBi was a superconductor surprised the researchers in the first place. Most superconductors start out as reasonably good conductors, with a lot of mobile electrons—an ingredient that YPtBi is lacking. According to the conventional theory, YPtBi would need about a thousand times more mobile electrons in order to become superconducting at temperatures below 0.8 Kelvin. And yet, upon cooling the material to this temperature, the team saw superconductivity happen anyway. This was a first sign that something exotic was going on inside this material.
...
For now, many open questions remain, including how such pairing could occur in the first place. "When you have this high-spin pairing, what's the glue that holds these pairs together?" says Paglione. "There are some ideas of what might be happening, but fundamental questions remain-which makes it even more fascinating."

(more at link.... https://phys.org/news/2018-04-superconductivityunusual-particle-interactions-possibilities-exotic.html  )

YBiPt which is kind of interesting CF wise as the carousels look balanced except for N/S between them .. Y is most the unbalanced one like Bi shoots charge through Pt with the channel hooks that ends in a weaker Y that then hooks the N/S with others? :



Could Mercury be switched out with Bi in this arrangement? Or would the carousels not properly stack the charge N/S without a Barium or Calcium -- or something without a full carousel (maybe multiple Y3 or something similar )...?  Mercury has two alpha-hooks while Bismuth doesn't...

ZrTe5 (Surprised Zr isn't involved in more SC discoveries)

How might this stack?
ZrNCl6
This looks like Zr-N-C-I6...

I would say that Platinum is more like Mercury. Pt has a denser core but less on the carousel level. I'm not sure how that dense core effects super-conductivity. The N/S hook stacks are the same for each element though, which makes it easier to replace one with the other.

Yttrium is a strange beast. No hook stack on the south position which makes it difficult to bond with other elements. You could bond the 5 proton stack on the south of Bismuth to the bottom of Yttrium such that they share that 5 proton stack. The core of Yttrium doesn't really want that much charge, but Bismuth can handle it with ease.

My guess at YPtBi would be to use Y to sit between Bi and Pt. This gives us 4 proton stacks on the north and south position of the molecule and keeps all bonding stacks at 5 protons. The N/S 4 proton stacks of the molecule pull in enough charge to saturate Y without blowing it apart. If we put that 5 proton stack of Bi on the outside then it would pull in too much charge for Y.

In my Molecular Bonding Language (MBL) it would look like this: !Bi-Y-Pt and I don't see any problem with !Bi-Y-Hg.

Okay I see your point. In my understanding I thought that the stacking would be Pt-BI-Y making CF from heavier to lighter structures (Y) on the North end. Almost like a triangular shape. But I guess, Y would be more like Ba in this example? The goal is "instability" as they mentioned in the research which is to limit the carousel CF in terms of Miles.

Strange that there is only 1 Zr but 5 Te. I thought it should be the other way around. Te can certainly bond to itself in those N/S positions and the connection points between Zr and Te would have 3 protons in each stack. The Te to Te bonds would have 4.

(Te)2-Zr-(Te)3

These molecules seem to have balanced N/S stacks. Miles states that an unbalanced N to S creates conduction but super-conductivity is not conduction, it is the loss of resistance. So I'm not sure if we still need the unbalanced stack sizes or if we can balance them. I don't see any reason not the be able to balance them, although it does allow charge flow in both directions. Maybe the fact that there are an odd number of one side and an even number on the other side of the central atom is enough to cause a direction for charge flow.

ZrNCl6: N-(Cl)3-Zr-(Cl)3 Not sure about flipping any of those elements.

Well I think this little discussion has shown the usefulness of MBL. If I had it implemented now we could be looking at these molecules rather than having to imagine them.

As a first cut, I will be implementing a web page that allows you to enter the MBL and it will generate the molecule for you using the AtomicViewer graphics code. In the long run, I would like a server that allows you to specify the MBL on the URL and it returns an image of the molecule. I realised that this requires re-coding the graphics into another language which I could use on the server. It is possible to use Javascript, through Node.js, but I prefer other languages for server-side coding. My server also does not have a graphics card, so I have to deal with that too. A web page and an image export function will get us by.

Did you know that you can press the 'P' key to save an image in AtomicViewer?

Well Nevyn, for the MBL that would be really cool!

Nevyn wrote:Did you know that you can press the 'P' key to save an image in AtomicViewer?

Didn't know that, I'll use it.

Just wanted to post this link on Iron-based SCs:

-------
https://en.wikipedia.org/wiki/Iron-based_superconductor

Much of the interest is because the new compounds are very different from the cuprates and may help lead to a theory of non-BCS-theory superconductivity.

More recently these have been called the ferropnictides. The first ones found belong to the group of oxypnictides. Some of the compounds have been known since 1995,[6] and their semiconductive properties have been known and patented since 2006.[7]
...

A subset of iron-based superconductors with properties similar to the oxypnictides, known as the 122 iron arsenides, attracted attention in 2008 due to their relative ease of synthesis.

Wikipedia wrote:The crystalline material, known chemically as LaOFeAs, stacks iron and arsenic layers, where the electrons flow, between planes of lanthanum and oxygen. Replacing up to 11 percent of the oxygen with fluorine improved the compound — it became superconductive at 26 kelvin, the team reports in the March 19, 2008 Journal of the American Chemical Society. Subsequent research from other groups suggests that replacing the lanthanum in LaOFeAs with other rare earth elements such as cerium, samarium, neodymium and praseodymium leads to superconductors that work at 52 kelvin.[5]

LaOFeAs



Fluorine (F)

La-substitutes:
--------



.....

Coexistence of Superconductivity and Antiferromagnetism in (Li0.8Fe0.2) OHFeSe

Published: March 01, 2015
Author(s)
X. F. Lu, N. Z. Wang, Hui Wu, Y. P. Wu, D. Zhao, X. Z. Zeng, X. G. Luo, T. Wu, W. Bao, G. H. Zhang, F. Q. Huang, Qingzhen Huang, X. H. Chen

Abstract

FeSe-derived superconductors show some unique behaviors relative to iron-pnictide superconductors, which are very helpful to understand the mechanism of superconductivity in high-Tc iron-based superconductors. The low-energy electronic structure of the heavily electron-doped AxFe2Se2 (A=K, Rb, Cs) deomonstrates that interband scattering or Fermi surface nesting is not a necessary ingredient for the unconventional superconductivity in iron-based superconductors. The superconducting transition temperature (Tc) in the one-unite-cell FeSe on SrTiO3 substrate can reach as high as ~65 K, largely transcending the bulk Tc of all known iron-based superconductors. However, in the case of AxFe2Se2, the inter-grown antiferromagnetic insulating phase makes it difficult to study the underlying physics. Superconductors of alkali metal ions and NH3 molecules or organic-molecules intercalated FeSe and single layer or thin film FeSe on SrTiO3 substrate are extremely air-sensitive, which prevents the further investigation of their physical properties. Therefore, it is urgent to find a stable and accessible FeSe-derived superconductor for physical property measurements so as to study the underlying mechanism of superconductivity. Here, we report the air-stable superconductor (Li0.8Fe0.2)OHFeSe with high temperature superconductivity at ~40 K synthesized by a novel hydrothermal method. The crystal structure is unambiguously determined by the combination of X-ray and neutron powder diffraction and nuclear magnetic resonance. It is also found that an antiferromagnetic order coexists with superconductivity in such new FeSe-derived superconductor. This novel synthetic route opens a new avenue for exploring other superconductors in the related systems. The combination of different structure characterization techniques helps to complementarily determine and understand the details of the complicated structures.
Citation: Nature Materials
Volume: 14

https://www.nist.gov/publications/coexistence-superconductivity-and-antiferromagnetism-li08fe02-ohfese

...........

https://arxiv.org/pdf/1504.04436.pdf

Electronic Structure and Superconductivity of FeSe-Related Superconductors

Xu Liu1, Lin Zhao1, Shaolong He1, Junfeng He1, Defa Liu1, Daixiang
Mou1, Bing Shen1, Yong Hu1, Jianwei Huang1 and X. J. Zhou1;2;
1National Lab for Superconductivity,
Beijing National Laboratory for Condensed Matter Physics,
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
2Collaborative Innovation Center of Quantum Matter, Beijing, China
(Dated: November 24, 2014)

Abstract

The FeSe superconductor and its related systems have attracted much attention in the iron-based
superconductors owing to their simple crystal structure and peculiar electronic and physical prop-
erties. The bulk FeSe superconductor has a superconducting transition temperature (Tc) of 8 K;
it can be dramatically enhanced to 37 K at high pressure. On the other hand, its cousin system,
FeTe, possesses a unique antiferromagnetic ground state but is non-superconducting. Substitution
of Se by Te in the FeSe superconductor results in an enhancement of Tc up to 14.5 K and super-
conductivity can persist over a large composition range in the Fe(Se,Te) system. Intercalation of
the FeSe superconductor leads to the discovery of the AxFe2-ySe2 (A=K, Cs and Tl) system that
exhibits a Tc higher than 30 K and a unique electronic structure of the superconducting phase.
The latest report of possible high temperature superconductivity in the single-layer FeSe/SrTiO3
films with a Tc above 65 K has generated much excitement in the community. This pioneering
work opens a door for interface superconductivity to explore for high Tc superconductors. The
distinct electronic structure and superconducting gap, layer-dependent behavior and insulator-
superconductor transition of the FeSe/SrTiO3 films provide critical information in understanding
the superconductivity mechanism of the iron-based superconductors. In this paper, we present
a brief review on the investigation of the electronic structure and superconductivity of the FeSe
superconductor and related systems, with a particular focus on the FeSe films.

Paper Conclusions
● Single-layer FeSe has a much simpler structure, but is likely to
have one of highest Tc ’s of the Fe-based superconductors
● Measurements show lack of a hole-like Fermi surface at gamma
point and a nodeless, isotropic superconducting gap
● Current theories for the superconducting mechanism need to be
modified to describe all the results presented in this paper

https://courses.physics.illinois.edu/phys596/fa2013/StudentWork/Team1_final.pdf
......


FeSe



SrTiO(3)




The cause of high Tc superconductivity at the interface between FeSe and SrTiO3
May 9, 2016, Science China Press
https://phys.org/news/2016-05-high-tc-superconductivity-interface-fese.html



The temperature above which a superconductor turns into a normal conductor is called the superconducting transition temperature. Raising it to a point enabling practical applications is a dream in modern science and technology. In 1987, a superconductor with a transition temperature above the boiling point of liquid nitrogen was discovered. Today, several families of closely related superconducting compounds (some with even higher transition temperatures) are known. They are called the "cuprates," as they're built from copper oxides.

......

Influence of the Fluoride Atoms Doping on the FeSe Superconductor
A. D. Bortolozo1,2, A. D. Gueiros1, L. M. S. Alves1, C. A. M. dos Santos1
1Departamento de Engenharia de Materiais, Escola de Engenharia de Lorena—USP, Lorena, Brazil; 2Universidade Federal de Itajubá, Campus de Itabira, Itabira, Brazil.
Email: ausdinirbortolozo@unifei.edu.br
Received March 29th, 2012; revised May 2nd, 2012; accepted July 3rd, 2012

ABSTRACT

It is reported the influence of the interstitial atoms doping on the FeSe superconductor. Polycrystalline samples with FeSeFx and FeSeBx nominal compositions were prepared by solid state reaction. An enhancement of the superconducting transition temperature was observed in the temperature dependence of the electrical resistivity curve to the FeSeF0.015 sample. R(T) data display superconducting behavior close to 12 K. The Tc increased with F doping by up to 50%. In contrast, boron doping no change the superconducting properties of the FeSe compound. As the FeSe1–xTex system the fluoride doping introduce a negative chemical pressure in the FeSe superconductor. This fact suggests that fluoride doping have changed the electronic properties of the FeSe phase.
....
Here we report the influence of interstitial doping on the FeSe superconduc-tor. We found that the FeSe + 0.5% FeF3 shows super-conducting transition like Fe (SeTe) solid solution. On the other hand, the low content boron atoms doping do not change the electric and magnetic properties of FeSe su-perconductor.

http://file.scirp.org/pdf/MSA20120900007_85314801.pdf

I have create a new topic for discussion about MBL and a formal declaration of the language and its syntax:

https://milesmathis.forumotion.com/t464-molecular-bonding-language

Let's start using this new language!

Formula: ZrNCl6
MBL: (Cl)3-N-Zr-(Cl)3
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=(Cl)3-N-Zr-(Cl)3&align=X&atom=nucleus

Formula: ZrTe5
MBL: (Te)2-Zr-(Te)3
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=(Te)2-Zr-(Te)3&align=X&atom=nucleus

Formula: YBiPt
MBL: !Bi-Y-Pt
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=!Bi-Y-Pt&align=X&atom=nucleus

Formula: FeSe
MBL: Fe-Se
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=Fe-Se&align=X&atom=nucleus




Formula: SrTiO3
MBL: Ti-Sr-(O)3
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=Ti-Sr-(O)3&align=X&atom=nucleus

Formula: LaOFeAs
MBL: La-As-Fe-O
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=La-As-Fe-O&align=X&atom=nucleus

Formula: HgBaCaCu
MBL: Ca-Hg-Ba-Cu
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=Ca-Hg-Ba-Cu&align=X&atom=nucleus




Formula: HgBaKCu
MBL: K-Hg-Ba-Cu
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=K-Hg-Ba-Cu&align=X&atom=nucleus

All of these are open for discussion. They are just my quick guesses. I'm looking at the bonds and deciding if the number of protons is OK and trying to keep lo-hi-lo numbers across the chain. The outer stacks I try to make unbalanced, but am not too concerned if they are not.

Quick plug on Graphene:
...........
Rare element to provide better material for high-speed electronics
May 24, 2018 by Kayla Wiles, Purdue University


Read more at: https://phys.org/news/2018-05-rare-element-material-high-speed-electronics.html#jCp

Purdue researchers have discovered a new two-dimensional material, derived from the rare element tellurium, to make transistors that carry a current better throughout a computer chip.

The discovery adds to a list of extremely thin, two-dimensional materials that engineers have tried to use for improving the operation speed of a chip's transistors, which then allows information to be processed faster in electronic devices, such as phones and computers, and defense technologies like infrared sensors.

Other two-dimensional materials, such as graphene, black phosphorus and silicene, have lacked either stability at room temperature or the feasible production approaches required to nanomanufacture effective transistors for higher speed devices.

"All transistors need to send a large current, which translates to high-speed electronics," said Peide Ye, Purdue's Richard J. and Mary Jo Schwartz Professor of Electrical and Computer Engineering. "One-dimensional wires that currently make up transistors have very small cross sections. But a two-dimensional material, acting like a sheet, can send a current over a wider surface area."

Tellurene, a two-dimensional film researchers found in the element tellurium, achieves a stable, sheet-like transistor structure with faster-moving "carriers—meaning electrons and the holes they leave in their place. Despite tellurium's rarity, the pros of tellurene would make transistors made from two-dimensional materials easier to produce on a larger scale. The researchers detail their findings in Nature Electronics.


Read more at: https://phys.org/news/2018-05-rare-element-material-high-speed-electronics.html#jCp

https://phys.org/news/2018-05-rare-element-material-high-speed-electronics.html#nRlv

...........

One-atom-thick sheets of carbon—known as graphene—have a range of electronic properties that scientists are investigating for potential use in novel devices. Graphene's optical properties are also garnering attention, which may increase further as a result of research from the A*STAR Institute of Materials Research and Engineering (IMRE). Bing Wang of the IMRE and his co-workers have demonstrated that the interactions of single graphene sheets in certain arrays allow efficient control of light at the nanoscale.

Light squeezed between single graphene sheets can propagate more efficiently than along a single sheet. Wang notes this could have important applications in optical-nanofocusing and in superlens imaging of nanoscale objects. In conventional optical instruments, light can be controlled only by structures that are about the same scale as its wavelength, which for optical light is much greater than the thickness of graphene. By utilizing surface plasmons, which are collective movements of electrons at the surface of electrical conductors such as graphene, scientists can focus light to the size of only a few nanometers.

Wang and his co-workers calculated the theoretical propagation of surface plasmons in structures consisting of single-atomic sheets of graphene, separated by an insulating material. For small separations of around 20 nanometers, they found that the surface plasmons in the graphene sheets interacted such that they became 'coupled' (see image). This theoretical coupling was very strong, unlike that found in other materials, and greatly influenced the propagation of light between the graphene sheets.



Read more at: https://phys.org/news/2012-12-theoretical-numerical-graphene-sheets-reveals.html#jCp

"Nematicity" is a focus with Superconductors. MBE might be a worth a lengthy investigation with the C.F.:
----------
LaBaCa2Cu4O

https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=LaBaCa2Cu4O8&align=X
----------------
Background:
https://en.wikipedia.org/wiki/Epitaxially
https://en.wikipedia.org/wiki/Molecular_beam_epitaxy
----------------
https://experts.umn.edu/en/publications/what-drives-nematic-order-in-iron-based-superconductors (more at link...)

What drives nematic order in iron-based superconductors?

R. M. Fernandes, A. V. Chubukov, J. Schmalian


Abstract

Although the existence of nematic order in iron-based superconductors is now a well-established experimental fact, its origin remains controversial. Nematic order breaks the discrete lattice rotational symmetry by making the x and y directions in the iron plane non-equivalent. This can happen because of a regular structural transition or as the result of an electronically driven instability-in particular, orbital order or spin-driven Ising-nematic order. The latter is a magnetic state that breaks rotational symmetry but preserves time-reversal symmetry. Symmetry dictates that the development of one of these orders immediately induces the other two, making the origin of nematicity a physics realization of the 'chicken and egg problem'. In this Review, we argue that the evidence strongly points to an electronic mechanism of nematicity, placing nematic order in the class of correlation-driven electronic instabilities, like superconductivity and density-wave transitions. We discuss different microscopic models for nematicity and link them to the properties of the magnetic and superconducting states, providing a unified perspective on the phase diagram of the iron pnictides.

----

Electronic nematicity in a cuprate superconductor and beyond
Monday, October 2, 2017 - 2:30pm

Over the course of extensive experimental studies of La2-xSrxCuO4 films synthesized by molecular beam epitaxy, we discovered that a spontaneous voltage develops across the sample, transverse to the electrical current. This unusual metallic state, in which the rotational symmetry of the electron fluid is spontaneously broken, occurs in a large temperature and doping region. The superconducting state always emerges out of this nematic metal state. I will also present our results in searching for electronic nematicity in other oxides, implying it may be pervasive among strongly-correlated materials.

http://physics.berkeley.edu/news-events/events/20171002/electronic-nematicity-in-a-cuprate-superconductor-and-beyond

https://www.nextbigfuture.com/2016/02/electronic-nematicity-as-universal.html

---------
Scientists use soft x-ray scattering in superconductivity research

The scientists used a novel technique called soft x-ray scattering at the Canadian Light Source synchrotron in Saskatoon to probe electron scattering in specific layers in the cuprate crystalline structure. Specifically, they looked at the individual cuprate (CuO2) planes where electronic nematicity takes place, versus the crystalline distortions in between the CuO2 planes.

Electronic nematicity happens when the electron orbitals align themselves like a series of rods. The term nematicity commonly refers to when liquid crystals spontaneously align under an electric field in liquid crystal displays. In this case, the electron orbitals enter the nematic state as the temperature drops below a critical point.

Future work will tackle how electrons can be tuned for superconductivity

Although there is not yet an agreed upon explanation for why electronic nematicity occurs, it may ultimately present another knob to tune in the quest to achieve the ultimate goal of a room temperature superconductor.

“Future work will tackle how electronic nematicity can be tuned, possibly to advantage, by modifying the crystalline structure,” says Hawthorn.

Disentangling intertwined orders

In copper oxide superconductors, several types of order compete for supremacy. In addition to superconductivity, researchers have found periodic patterns in charge density (CDW order), as well as an asymmetry in the electronic density within the unit cell of some cuprates (nematicity). CDW order has been detected in the underdoped regime of all major cuprate families, but the ubiquity of nematicity is less clear. Achkar et al. used resonant x-ray scattering to find that, in the copper oxide planes of three lanthanum-based cuprates, nematicity has a temperature dependence distinct from that of a related structural distortion. This implies that there are additional, electronic mechanisms for nematicity

Abstract

In underdoped cuprate superconductors, a rich competition occurs between superconductivity and charge density wave (CDW) order. Whether rotational symmetry-breaking (nematicity) occurs intrinsically and generically or as a consequence of other orders is under debate. Here, we employ resonant x-ray scattering in stripe-ordered superconductors (La,M)2CuO4 to probe the relationship between electronic nematicity of the Cu 3d orbitals, structure of the (La,M)2O2 layers, and CDW order. We find distinct temperature dependences for the structure of the (La,M)2O2 layers and the electronic nematicity of the CuO2 planes, with only the latter being enhanced by the onset of CDW order. These results identify electronic nematicity as an order parameter that is distinct from a purely structural order parameter in underdoped striped cuprates.
https://www.nextbigfuture.com/2016/02/electronic-nematicity-as-universal.html (more at link...)

Abrupt change of the superconducting gap structure at the nematic critical point in FeSe1−xSx

Yuki Sato, Shigeru Kasahara, Tomoya Taniguchi, Xiangzhuo Xing, Yuichi Kasahara, Yoshifumi Tokiwa, Youichi Yamakawa, Hiroshi Kontani, Takasada Shibauchi, and Yuji Matsuda

PNAS February 6, 2018. 115 (6) 1227-1231; published ahead of print January 23, 2018. https://doi.org/10.1073/pnas.1717331115

Significance

Electronic nematicity that spontaneously breaks the rotational symmetry of the underlying crystal lattice has been a growing issue in high-temperature superconductivity of iron pnictides/chalcogenides and cuprates. FeSe1 − xSx, in which the nematicity can be tuned by isoelectronic sulfur substitution, offers a fascinating opportunity to clarify the direct relationship between the nematicity and superconductivity. Here, we discover a dramatic change in the superconducting gap structure at the critical concentration of sulfur where the nematicity disappears, i.e., nematic critical point. Our observation provides direct evidence that the orbital-dependent nature of the critical nematic fluctuations has a strong impact on the superconducting pairing interaction.

http://www.pnas.org/content/115/6/1227

--------------


Nematicity, magnetism and superconductivity in FeSe

Anna E Böhmer1,3 and Andreas Kreisel2

Published 15 December 2017 • 2017 IOP Publishing Ltd
Journal of Physics: Condensed Matter, Volume 30, Number 2

Abstract

Iron-based superconductors are well known for their complex interplay between structure, magnetism and superconductivity. FeSe offers a particularly fascinating example. This material has been intensely discussed because of its extended nematic phase, whose relationship with magnetism is not obvious. Superconductivity in FeSe is highly tunable, with the superconducting transition temperature, T c, ranging from 8 K in bulk single crystals at ambient pressure to almost 40 K under pressure or in intercalated systems, and to even higher temperatures in thin films. In this topical review, we present an overview of nematicity, magnetism and superconductivity, and discuss the interplay of these phases in FeSe. We focus on bulk FeSe and the effects of physical pressure and chemical substitutions as tuning parameters. The experimental results are discussed in the context of the well-studied iron-pnictide superconductors and interpretations from theoretical approaches are presented.

http://iopscience.iop.org/article/10.1088/1361-648X/aa9caa

This article provides pretty good background on "nematicity":
http://www.nature.com/nature/journal/v486/n7403/full/nature11178.html

BaFe2As2
https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=BaFe2As2&align=Z
-------------

Asymmetry may provide clue to superconductivity

Iron-based high-temp superconductors show unexpected electronic asymmetry

HOUSTON — (June 20, 2012) — Japanese and U.S. physicists are offering new details this week in the journal Nature regarding intriguing similarities between the quirky electronic properties of a new iron-based high-temperature superconductor (HTS) and its copper-based cousins.

While investigating a recently discovered iron-based HTS, the researchers found that its electronic properties were different in the horizontal and vertical directions. This electronic asymmetry was measured across a wide range of temperatures, including those where the material is a superconductor. The asymmetry was also found in materials that were “doped” differently. Doping is a process of chemical substitution that allows both copper- and iron-based HTS materials to become superconductors.


Andriy Nevidomskyy
“The robustness of the reported asymmetric order across a wide range of chemical substitutions and temperatures is an indication that this asymmetry is an example of collective electronic behavior caused by quantum correlation between electrons,” said study co-author Andriy Nevidomskyy, assistant professor of physics at Rice University in Houston.

The study by Nevidomskyy and colleagues from Kyoto University in Kyoto, Japan, and the Japan Synchrotron Radiation Research Institute (JASRI) in Hyogo offers new clues to scientists studying the mystery of high-temperature superconductivity, one of physics’ greatest unsolved mysteries.

Superconductivity occurs when electrons form a quantum state that allows them to flow freely through a material without electrical resistance. The phenomenon only occurs at extremely cold temperatures, but two families of layered metal compounds — one based on copper and the other on iron — perform this mind-bending feat just short of or above the temperature of liquid nitrogen — negative 321 degrees Fahrenheit — an important threshold for industrial applications. Despite more than 25 years of research, scientists are still debating what causes high-temperature superconductivity.

Copper-based HTSs were discovered more than 20 years before their iron-based cousins. Both materials are layered, but they are strikingly different in other ways. For example, the undoped parent compounds of copper HTSs are nonmetallic, while their iron-based counterparts are metals. Due to these and other differences, the behavior of the two classes of HTSs are as dissimilar as they are similar — a fact that has complicated the search for answers about how high-temperature superconductivity arises.


One feature that has been found in both compounds is electronic asymmetry — properties like resistance and conductivity are different when measured up and down rather than side to side. This asymmetry, which physicists also call “nematicity,” has previously been found in both copper-based and iron-based high-temperature superconductors, and the new study provides the strongest evidence yet of electronic nematicity in HTSs.

http://news.rice.edu/2012/06/20/asymmetry-may-provide-clue-to-superconductivity/

Looking at the S.C. LaBaCa2Cu4O8 above made me think it looked as if Hg could be swapped in as well and sure enough they have one:
HgBa2Ca3Cu4O10
https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=HgBa2Ca3Cu4O10&align=X
------

In this note we report preliminary results concerning a remarkably strong phonon self- energy effect observed in HgBa2Ca3Cu4O10‡d (Hg-1234) superconductor. We measured single crystals in a Hg-1234 ceramic pellet (Tc ˆ 123 K, determined by zero resistance) prepared by a high-pressure high-temperature technique [2]. Micro-Raman scattering spectra were collected with a Dilor XY multichannel spectrometer equipped with an optical microscope in an exact backscattering geometry using the 647.1 nm laser line. The samples were kept and cooled in a continuous flow liquid helium cryostat. In Fig. 1 we present some typical Raman spectra of a large Hg-1234 grain in parallel polarization and at different temperatures. At room temperature, the absence of sharp phonon features in the 450 to 600 cmÿ1 region indicates that the grain surface is normal to the c-axis [2]. Above Tc, one can see three weak features at 240, 360 and 410 cmÿ1 superimposed on a nearly flat background, and the spectra show little change with temperature. The rather weak 240 and 360 cmÿ1 phonons exhibit strong coupling with the scattering continuum manifested by an asymmetric lineshape (Fano profile). Below Tc, a dramatic spectral change occurs: the spectral background shows a clear redistribu- tion upon entering the superconducting state and the weak phonon features strongly increase in intensity with decreasing temperature, accompanied by an abrupt change in peak position and line- width. In addition, two weak new peaks, at 480 and 570 cmÿ1, appear at low temperatures. The remarkable spectral change in Hg-1234 below Tc is clearly related to the opening of the superconducting gap and to coupled electron±phonon excitations: the piled up density of states (the electronic scattering peak) strongly modifies the phonon self-energy. Preliminary calculations show that the oscillator strength of the phonons observed below Tc is induced by the admixture of pair-breaking transitions via electron±phonon interaction. Such superconductivity-induced effects, particularly the increase in the phonon intensity, are among the strongest ones observed in the cuprate superconductors so far [3].

https://docslide.us/documents/strong-electronphonon-interactions-in-hgba2ca3cu4o10-superconductor.html

Was thinking of these Mathis quotes and the B-Field after reading about "nematicity":
-----------
SUPERCONDUCTIVITY
In short, Copper conducts well because it channels charge efficiently from south pole to north pole. All elements normally channel from pole to equator, and Copper still channels a large percentage that way; but Copper channels more from pole to pole than any other element except Silver. To understand exactly why, you will have to read that paper, but studying Copper helps us understand what conduction is as a matter of charge channeling. Once we understand that, we can comprehend what causes superconduction.
http://milesmathis.com/conduct.html

Solid Light? No, just another bad interpretation of the Charge Field

And if you think the quantum mechanical explanation is more rigorous, you aren't paying attention.  Notice it includes an electron-phonon interaction.  There is no such beast as a phonon.  It is another fudge.  It was dreamed up to fill a hole, like the polariton and the qubit and the quasi-particle and the virtual particle.  As with all other electron bonding theory, the Cooper pair was invented by simply ignoring and inverting the standing definitions of the charge field, and selling that as  a  new  piece  of  physics.    It  was  the  hamhanded  placement  of  an  attraction  in  the  field  where  a repulsion should have existed.   It would be like placing you in front of the Sun and telling you it was dark.
...
So  if  we  wish  to  explain  superconductivity  sensibly,  we  have  to  stick  to  the  particles  we  know  are there:  the  photons,  electrons,  and  nuclei.   That  was  impossible  to  do  without  knowing  exactly what charge was, and how it was being created and transferred; since the mainstream hasn't known that, they couldn't solve these problems sensibly.  But since I now know that, explaining superconductivity is no longer that difficult.  We simply have to follow the charge streams through the nuclear structures.  Even with my general theory of charge channeling, explaining superconductivity would be nearly impossible without  diagrams  of  the  nuclei  involved,  but  I  have  also  deduced  those,  so  we  should  make  quick progress.  I have previously provided my readers with diagrams of Copper, Oxygen, Calcium, Barium, and  Mercury,  so  we  should  be  able  to  build  an  entire  ceramic  molecule,  diagramming  the  charge channels through the full structure.  Once we have understood high-temperature superconduction, we will be in a position to read the new data from Princeton in a completely different way, without needing any quasi-particles, dimers, qubits, or other mathematical tricks.

But when we are looking at what we call electrical conduction, we are looking at the stream from south pole to north.  This stream is linear, directionalized, and coherent.  If we align the poles of adjacent nuclei, we create longer lines of conduction.  As you can probably see already, this explains the Meissner Effect in superconductivity, where interior magnetic lines disappear.  We have never been given a simple mechanical explanation for that, but my diagram of Copper supplies it immediately.  If this Copper nucleus begins superconducting, that simply means that all photons being recycled are going from pole to pole.  None are being recycled out the equatorial  or  carousel  level.   As  we  know,  the  magnetic  field  lines  are  always  orthogonal  to  the electrical field lines.  Well, the electrical fields lines go with the conduction.  They run south to north here.  The magnetic field lines are then orthogonal to that and in a circle, by the old right hand rule. Well, since we have no photons being emitted out the equator in this case, we have no magnetic field being  created.   Both  the  electrical  field  and  magnetic  field  are  caused  by  the  charge  field,  and  the charge field is just the recycled photons.  Photons that are recycled from south to north in a line create the electrical field, and photons that are recycled through the carousel level create the magnetic field. So if all charge is channeled south to north as through charge, nothing is left to create the magnetic  field.  It disappears.  This disappearance is what we call the Meissner Effect.

This tells us how the magnetic field and electrical field are related at the foundational level.  Given my theory,  we  should  have  expected the  magnetic  field  to  go  to  zero  when  the  electrical  field  was  at  a maximum,  since  the  field  creation  is a  zero-sum game.   Since  the  same  charge  field  creates  both,  a maximal electrical conduction implies a zero magnetic field.  If all charge photons are being conducted, none can be left to create the magnetic field (internally).  Since all photons are spinning, the external electrical  field  will  still  have  a  potential  magnetic  component,  but  in  the  atoms  themselves,  there  is nothing that we would call a magnetic field.  Given superconduction, those internal field lines are gone. Now, if we plug an Oxygen into that Copper nucleus, we can increase conduction even more, since the Oxygen  will  plug  in  on the  pole  (see  diagram  below).  Our  recycling  engine  will  be  bigger,  having more  fans  to  pull  charge  through  (as  it  were).   And  the  added  fans  will  all  be  aligned  on  the  pole, increasing through charge.  Under normal circumstances, CuO will still recycle some of the charge out the carousel level, so we will not have superconduction.  This begs the question: how can we cause superconduction?  What would we do to maximize conduction?  Well, obviously we would minimize charge recycling on the equator.  That would force all recycling to happen on the pole.  The easiest way to do that is stop the carousel level from spinning.  If the nucleus stops spinning about its axis, we no longer have more angular momentum on the equator, and no reason for charge to recycle out that way. This  is  what  happens  with  supercold  superconduction.  But  what  happens  with  warmer superconduction?  To figure that out, we have to look at how it is created in the lab.  We need to add  Mercury, Calcium and Barium to our diagram.


http://milesmathis.com/solidlight.pdf
----------------------------------------------

98. What is "Charge"?
...
Also remember that any other proton that enters the field of our first proton will also be emitting its own B-field. These fields may interfere to some extent, but we would still expect the combined field to be more repulsive than either field taken alone. This must mean that any protons will be driven away from each other much faster than an electron will be driven away.

You will say that we still have repulsion of both the electron and the proton, but we have not brought the newly upgraded gravitational field into the mix. This field is going to cause an apparent attraction to all particles, just like the traditional field. All particles are going to appear to “fall” toward our gravitating proton, and they are all going to fall at the same rate. Standard gravity theory, so far. But let us use Einstein’s equivalence principle to reverse only our terminology. Instead of saying that all objects are falling toward our proton, we say that our proton is chasing all objects at the same rate. An acceleration in one direction is equal to an acceleration in the other direction, in a rectilinear field.

So, in order to explain both positive charge and negative charge, we only have to propose that the proton is chasing the electron fast enough to catch it, but not fast enough to catch the proton. This gives us an apparent attraction of one, and an apparent repulsion of the other.

Another way to state this is to give numbers to the two repulsions. Say the repulsion of proton by proton by the B-field causes an acceleration of 10. And say that the repulsion of electron by proton by the B-field causes an acceleration of 2. All we have to propose is that our central proton is accelerating gravitationally at a rate greater than 2 and less than 5. Anywhere in that gap, we will see repulsion of the two protons and an attraction of the electron.

That is the simple mechanical explanation of charge.

What about current in a wire? You will ask how my theory explains that. Again, quite easily. Free electrons travel at high speed in a conducting wire, or any conductor, because the B-field is moving in only one direction in that substance. The B-field acts as a river, moving the electrons along by direct contact. This B-field river can be created in any number of ways, either by having lots of radiating particles at one end of the wire and few or none at the other, or by directionalizing the B-field through the shape of the molecules in the substance. Some molecules block certain directions of the B-field, simply by getting in the way. Of course I am simplifying to a very great degree here; but I can do so since, once my fields are understood, the questions are no longer difficult. Given my method, you can answer your own questions; and they no longer look very compelling to me.

Organic Superconductors -- they have Bechgaard salts as a close run-up but nothing really hits the mark at the moment:

https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=H12C10Se4&align=X



Why study organic superconductors?

One aspect of organic superconductors such as the Bechgaard salts that makes them interesting topics of study are that the are strongly anisotropic in structure (for more information see the crystal structure section), so that their conductivity differs along the three axes by multiple orders of magnitude. This inhibits the generation of the circular currents that cause the Meissner effect, potentially significantly increasing the critical field of these materials. Furthermore, the superconducting electrons in the Bechgaard salts are believed to form with triplet spin configurations, so that both electron spins are in the same direction, and the pairs could potentially be unaffected by magnetic fields large enough to disrupt any singlet configuration Cooper pair. Therefore, organic superconductors are good candidates for being very high critical field materials, which is important in many applications of superconductors, in particular the carrying of large amounts of current, since the limiting factor in the current capacity of superconducting wires is that too much current will make a magnetic field strong enough to destroy the superconductivity.

Even if organic superconductors do not exhibit high critical fields, they are still important to study since the standard theory of superconductivity does not apply very well to them. Their unique structure causes the current to move primarily in one or two dimensions, which creates many considerations not present in metallic superconductors, and the probable existence of spin-triplet electron pairings suggest that the mechanism for superconductivity in organic superconductors is significantly different than in regular superconductors.

http://hoffman.physics.harvard.edu/materials/organic/background.php#special

-------

The Bechgaard salts are a class of charge transfer compounds in which one electron from a pair of TMTSF molecules is transferred to the anion--the resultant positive charge on the TMTSF molecules is shared throughout the structure due to the dense packing of these flat donor molecules. The negative charges are shared on the channels of anions separated from the TMTSF molecules. In addition, the size of the anion molecule chosen dictates the spacing of the TMTSF columns and thus has an effect similar to that of an applied pressure as seen on the phase diagram. In short, both the crystal structure and the geometry of the individual TMTSF molecule are critical in ensuring the charge transfer throughout the bulk sample.

Crystal Structure

Fig 2 Carbon shown in orange, selenium in yellow, potassium in blue, and fluorine in green. Figure taken from Claude, Jerome, Physics World (1998).

The crystal structure of (TMTSF)2PF6 is shown at left with the a-axis (the stacking axis with the highest conductivity) perpendicular to the plane of the image. The TMTSF and TMTTF families both exhibit this crystal structure with stacks of organic molecules separated by the columns of negatively charged anions. The organic molecules are nearly flat and aligned in a zigzag pattern down the a-axis with a slight dimerization (the molecular orbital picture described below highlights the overlap with this alternations). The small distance between one stack and the other in the b direction leads to a slight overlap in this direction and a weak 2-D character as pressure increases.

In addition, the orientation and symmetry of the anion can have a large impact on the overall properties. For the non-centrosymetric anions, those without an inversion center, such as ClO4 and FeO4, there are two relative orientations of the anions with respect to the surrounding molecules with equivalent energies. At high temperatures, we see a thermal mixture of both forms. However, at lower temperatures the structure can undergo a disorder → order transition if cooled sufficiently slowly such that all the anions are ordered in the same fashion.

Electronic Structure
Electrical Conductivity: Molecular Orbital Picture

Electrical conductivity in the Bechgaard salts arises under normal conditions because each pair of TMTSF or TMTTF molecules donates an electron to the anion acceptor. In most cases the negatively charged anion forms a closed shell and does not contribute to the overall conductivity, so current is carried by the holes created on the TMTSF or TMTTF chains, and the conductivity depends on the hole density and the complementary mobility.

http://hoffman.physics.harvard.edu/materials/organic/properties.php#crystal


---------
https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=H12C10Se4&align=X

Tetramethyltetraselenafulvalene (CAS 55259-49-9)
同義語 TMTSF
アプリケーション： A compound that exhibits superconducting properties
CAS 番号: 55259-49-9
Molecular Weight: 448.04
Molecular Formula: C10H12Se4
Supplemental Information: This is classified as a Dangerous Good for transport and may be subject to additional shipping charges.
https://www.scbt.com/scbt/ja/product/tetramethyltetraselenafulvalene-55259-49-9

-----

Potential "curiosity" with a Mathis explanation:

https://www.chem.ubc.ca/far-infrared-reflectivity-bis-tetramethyltetraselenafulvalene-hexafluoroarsenate-tmtsf2asf6-throug-0

Title -- FAR-INFRARED REFLECTIVITY OF BIS-TETRAMETHYLTETRASELENAFULVALENE HEXAFLUOROARSENATE [(TMTSF)2ASF6] THROUGH THE SPIN-DENSITY-WAVE PHASE-TRANSITION
Publication Type Journal Article
Year of Publication 1987

Details on the Salt-formations:
Crystal structure of tetra-methyl-tetra-thia-fulvalenium (1S)-camphor-10-sulfonate dihydrate.
https://europepmc.org/articles/PMC4518967/

Structure of Acetylcholine using Nevyn's MBL... :
https://en.wikipedia.org/wiki/Acetylcholine
https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=NO2C7H16&align=X

Here is my attempt at Acetylcholine:

Formula: NO2C7H16
MBL: H-(C{H,H})2-N{H,H}(C{H,H})3-O-C{H,H}C-O-H
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=H-(C{H,H})2-N{H,H}(C{H,H})3-O-C{H,H}C-O-H&align=X&atom=nucleus




I built Choline first to see where it came from:

Formula: C5H14NO
MBL: H-(C{H,H})2-N{H,H}(C{H,H})3-O-H
URL: https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=H-(C{H,H})2-N{H,H}(C{H,H})3-O-H&align=X&atom=nucleus

Cool (organized) pics. They look good in the MBL engine.  I was thinking of the properties of Acetylcholine...how is it so special?
------

Functions
Acetylcholine pathway.

Acetylcholine functions in both the central nervous system (CNS) and the peripheral nervous system (PNS). In the CNS, cholinergic projections from the basal forebrain to the cerebral cortex and hippocampus support the cognitive functions of those target areas. In the PNS, acetylcholine activates muscles and is a major neurotransmitter in the autonomic nervous system.

Cellular effects

Acetylcholine processing in a synapse. After release acetylcholine is broken down by the enzyme acetylcholinesterase.

Like many other biologically active substances, acetylcholine exerts its effects by binding to and activating receptors located on the surface of cells. There are two main classes of acetylcholine receptor, nicotinic and muscarinic. They are named for chemicals that can selectively activate each type of receptor without activating the other: muscarine is a compound found in the mushroom Amanita muscaria; nicotine is found in tobacco.

Nicotinic acetylcholine receptors are ligand-gated ion channels permeable to sodium, potassium, and calcium ions. In other words, they are ion channels embedded in cell membranes, capable of switching from a closed to open state when acetylcholine binds to them; in the open state they allow ions to pass through. Nicotinic receptors come in two main types, known as muscle-type and neuronal-type. The muscle-type can be selectively blocked by curare, the neuronal-type by hexamethonium. The main location of muscle-type receptors is on muscle cells, as described in more detail below. Neuronal-type receptors are located in autonomic ganglia (both sympathetic and parasympathetic), and in the central nervous system.

Is this like a para-"organic" superconductor? Are there properties that allow "nerves" to channel charge?
https://en.wikipedia.org/wiki/Neurotransmitter

https://upload.wikimedia.org/wikipedia/commons/thumb/d/d7/SynapseSchematic_lines.svg/1200px-SynapseSchematic_lines.svg.png

https://en.wikipedia.org/wiki/Choline_acetyltransferase

The muscarinic action of acetylcholine in the CNS is implicated in learning and memory. The loss of cholinergic innervation in the neocortex has been associated with memory loss, as is evidenced in advanced cases of Alzheimer's disease. In the peripheral nervous system, cholinergic neurons are implicated in the control of visceral functions such as, but not limited to, cardiac muscle contraction and gastrointestinal tract function.

Related on a completely different topic is the layout of this magnet? Do the Fe atoms link to the Nd atoms on each free alpha? If Hg and Ba are switched in for the Nds, then it becomes a S.C. -- just playing with these layouts. My apologies if this sounds too fast and loose.  

https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=Nd-B-Nd-Fe14&align=X

Nd2Fe14B
Nd₂Fe₁₄B domain structure imaged with MOKE
Fig. 1 MOKE image of the fractal domain pattern of Nd2Fe14B taken in the group of our collaborator Prof. Ruslan Prozorov.

The rare-earth magnetic alloy Nd2Fe14B is one of the strongest known permanent magnets and is widely used in industrial and commercial applications. In the thermally demagnetized state, Nd2Fe14B magnets display a high degree of fine-scale (~25nm) magnetic texture [1-2] and branched fractal-like domains [3-4] along the c-axis, that make them of interest for magnetic microelectromechanical applications (`Mag-MEMS'). This material has been studied in the past using magnetic force microscopy (MFM) [1,2,4,5], scanning electron microscopy (SEM) [5], and magneto-optic Kerr effect (MOKE) microscopy [3,4,6]. Our magnetic force microscope has additional cababilities that enable us to study the magnetic domains at smaller length-scales and lower temepratures than previous studies. Furthermore, we employ harder magnetic tips which we hope to use for domain manipulation.

http://hoffman.physics.harvard.edu/materials/NdFeB.php

I don't know what makes it special. These are complex molecules in an even more complex environment. My guess would be the amount of charge flow they can support. When acetylcholine binds to a receptor, it injects or extracts charge from it and this allows other parts of that receptor to operate differently.

As an example, suppose it injects charge into the receptor. Then the receptor starts to expand, which opens up its walls and allows other molecules to slip through.

Just a guess and probably completely wrong. This is a long way from my comfort zone.

That's a lot of iron!

I would guess that 8 of those go to the carousel levels of neodymium. That still leaves 6 to go in the main chain.

Maybe like this: (Fe-Fe-Nd[Fe,Fe,Fe,Fe])2-Fe-Fe-B
https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=(Fe-Fe-Nd[Fe,Fe,Fe,Fe])2-Fe-Fe-B&align=X&atom=nucleus

Nevyn wrote:

As an example, suppose it injects charge into the receptor. Then the receptor starts to expand, which opens up its walls and allows other molecules to slip through.

Just a guess and probably completely wrong. This is a long way from my comfort zone.

They do change their synaptic flow/ionic channelling by releasing chemical pre-cursors and such (charge related molecules) .  I'm thinking of how related cells may cause signaling for this as well. The brain's thought processes are pretty dependent on these reactions of glucose, glutamine and acetylcholine in just the right amounts.

And maybe why don't magnets/large metals near the head affect our thinking that much? These are just random thoughts on the topic. (as I lift a 30lbs metal kettle bell above my head... lol... the jocks were always a little dumber in school and I blame the charge field!).

I can see the "fractal-like domains" in the Fe and B. Cool as always. Is there room for fractals with Mathis at this level?


Fig. 1 MOKE image of the fractal domain pattern of Nd2Fe14B taken in the group of our collaborator Prof. Ruslan Prozorov.

http://hoffman.physics.harvard.edu/research/Hoffman-Laboratory-Research.pdf
http://hoffman.physics.harvard.edu/research.php

NbSe2


https://www.nevyns-lab.com/mathis/app/mbl/mbl.html?mbl=NbSe2&align=X

Do you know how long it would have taken me to build that molecule in my (very) old desktop atomic viewer? Days! Days, I tell ya!

If you wanted Nd2BFe14 a bit more symmetrical, then put the B in between the 2 middle Fe atoms instead of on the end. Not sure if that is required or not. If it was in the middle, it might cause a slight separation of charge flow between the 2 halves. Thus allowing southern charge to flow out of the carousel level of the southern Nd and the northern charge to flow out the carousel of the northern Nd. We want carousel output, as it is magnetic, so this might actually be the right choice.

Nevyn wrote:Do you know how long it would have taken me to build that molecule in my (very) old desktop atomic viewer? Days! Days, I tell ya!

Lol! I hear you! And I was excited to just look at it back in the day!

http://www.fractaluniverse.org/v2/?page_id=131
https://www.eurekalert.org/pub_releases/2015-09/ciot-afi092115.php


Public Release: 21-Sep-2015
Atomic fractals in metallic glasses

California Institute of Technology

The group did simulations and experiments to probe the atomic structure of metallic glass alloys of copper, zirconium, and aluminum. In crystalline solids like diamond or gold, atoms or molecules are arranged in an orderly lattice pattern. As a result, the local neighborhood around an atom in a crystalline material is identical to everywhere else in the material. In amorphous metals, every location within the material looks different--except, Greer and her colleagues found, when you zoom in to look at the distribution of atoms at the scale of two to three atomic diameters--about one nanometer. At this level, the same fractal pattern is present, regardless of location within the material. "Within the clusters of atoms that make up a metallic glass, atoms are arranged in a particular kind of fractal pattern called percolation," Chen says.

Other scientists have previously hypothesized that the atoms in metallic glasses are distributed fractally. However, this creates an apparent paradox: When atoms are distributed fractally, there should be empty space between them. However, metallic glasses--just like regular metals--are fully dense, meaning that they lack significant pockets of empty space.

"Our group has solved this paradox by showing that atoms are only arranged fractally up to a certain scale," Greer says. "Larger than that scale, clusters of atoms are packed randomly and tightly, making a fully dense material, just like a regular metal. So we can have something that is both fractal and fully dense."

The discovery was made with metallic glasses, but the group's conclusions about fractally arranged atomic structures can be applied to essentially any rigid amorphous material, like the glass in a windowpane or a frozen piece of chewing gum. "Amorphous metals can exhibit unique properties, like unusual strength and elasticity," Chen says. "Now that we know the structure of these materials, we can start studying how their atomic-level arrangement affects their large-scale properties."

In addition to applications within materials science, studies of naturally occurring fractal distributions are of high interest within the fields of mathematics, physics, and computer science. Fractals have been studied for centuries by mathematicians and physicists. Showing how they emerge in a metallic alloy provides a physical foundation for something that has only been studied theoretically.

###

Other Caltech co-authors on the paper, titled "Fractal atomic-level percolation in metallic glasses," include Qi An, a theoretical and computational materials scientist, and Professor William Goddard, the Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics.

Caltech's Cu46Zr54

Umm, Yeah, I'm not making that one!

FYI... I just updated the first page with all the links to render the S.C. molecules in the MBL Viewer:

https://milesmathis.forumotion.com/t456-partial-list-of-superconductors-to-build-out#3542

Interesting observation in light of the C.F.:
--------
Electrons break rotational symmetry in exotic low-temp superconductor

by Ariana Manglaviti, Brookhaven National Laboratory

Scientists have discovered that the transport of electronic charge in a metallic superconductor containing strontium, ruthenium, and oxygen breaks the rotational symmetry of the underlying crystal lattice. The strontium ruthenate crystal has fourfold rotational symmetry like a square, meaning that it looks identical when turned by 90 degrees (four times to equal a complete 360-degree rotation). However, the electrical resistivity has twofold (180-degree) rotational symmetry like a rectangle.

This 'electronic nematicity'—the discovery of which is reported in a paper published on May 4 in the Proceedings of the National Academy of Sciences—may promote the material's 'unconventional' superconductivity. For unconventional superconductors, standard theories of metallic conduction are inadequate to explain how upon cooling they can conduct electricity without resistance (i.e., losing energy to heat). If scientists can come up with an appropriate theory, they may be able to design superconductors that don't require expensive cooling to achieve their near-perfect energy efficiency.

"We imagine a metal as a solid framework of atoms, through which electrons flow like a gas or liquid," said corresponding author Ivan Bozovic, a senior scientist and the leader of the Oxide Molecular Beam Epitaxy Group in the Condensed Matter Physics and Materials Science (CMPMS) Division at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and an adjunct professor in the Department of Chemistry at Yale. "Gases and liquids are isotropic, meaning their properties are uniform in all directions. The same is true for electron gases or liquids in ordinary metals like copper or aluminum. But in the last decade, we have learned that this isotropy doesn't seem to hold in some more exotic metals."

Scientists have previously observed symmetry-breaking electronic nematicity in other unconventional superconductors. In 2017, Bozovic and his team detected the phenomenon in a metallic compound containing lanthanum, strontium, copper, and oxygen (LSCO), which becomes superconducting at relatively higher (but still ultracold) temperatures compared to low-temperature counterparts like strontium ruthenate. The LSCO crystal lattice also has square symmetry, with two equal periodicities, or arrangements of atoms, in the vertical and horizontal directions. But the electrons do not obey this symmetry; the electrical resistivity is higher in one direction unaligned with the crystal axes.

"We see this kind of behavior in liquid crystals, which polarize light in TVs and other displays," said Bozovic. "Liquid crystals flow like liquids but orient in a preferred direction like solids because the molecules have an elongated rod-like shape. This shape constrains rotation by the molecules when packed close together. Liquids are typically symmetric with respect to any rotation, but liquid crystals break such rotational symmetry, with their properties different in the parallel and perpendicular directions. This is what we saw in LSCO—the electrons behave like an electronic liquid crystal."

With this surprising discovery, the scientists wondered whether electronic nematicity existed in other unconventional superconductors. To begin addressing this question, they decided to focus on strontium ruthenate, which has the same crystal structure as LSCO and strongly interacting electrons.

At the Kavli Institute at Cornell for Nanoscale Science, Darrell Schlom, Kyle Shen, and their collaborators grew single-crystal thin films of strontium ruthenate one atomic layer at a time on square substrates and rectangular ones, which elongated the films in one direction. These films have to be extremely uniform in thickness and composition—having on the order of one impurity per trillion atoms—to become superconducting.

The crystal structure of strontium ruthenate, which is made up of ruthenium (red), strontium (blue), and oxygen (green). Credit: Brookhaven National Laboratory

To verify that the crystal periodicity of the films was the same as that of the underlying substrates, the Brookhaven Lab scientists performed high-resolution X-ray diffraction experiments.

"X-ray diffraction allows us to precisely measure the lattice periodicity of both the films and the substrates in different directions," said coauthor and CMPMS Division X-ray Scattering Group Leader Ian Robinson, who made the measurements. "In order to determine whether the lattice distortion plays a role in nematicity, we first needed to know if there is any distortion and how much."

Bozovic's group then patterned the millimeter-sized films into a "sunbeam" configuration with 36 lines arranged radially in 10-degree increments. They passed electrical current through these lines—each of which contained three pairs of voltage contacts—and measured the voltages vertically along the lines (longitudinal direction) and horizontally across them (transverse direction). These measurements were collected over a range of temperatures, generating thousands of data files per thin film.

Compared to the longitudinal voltage, the transverse voltage is 100 times more sensitive to nematicity. If the current flows with no preferred direction, the transverse voltage should be zero at every angle. That wasn't the case, indicating that strontium ruthenate is electronically nematic—10 times more so than LSCO. Even more surprising was that the films grown on both square and rectangular substrates had the same magnitude of nematicity—the relative difference in resistivity between two directions—despite the lattice distortion caused by the rectangular substrate. Stretching the lattice only affected the nematicity orientation, with the direction of highest conductivity running along the shorter side of the rectangle. Nematicity is already present in both films at room temperature and significantly increases as the films are cooled down to the superconducting state.

"Our observations point to a purely electronic origin of nematicity," said Bozovic. "Here, interactions between electrons bumping into each other appear to have a much stronger contribution to electrical resistivity than electrons interacting with the crystal lattice, as they do in conventional metals."

https://phys.org/news/2020-05-electrons-rotational-symmetry-exotic-low-temp.html

Researchers detect a supercurrent at the edge of a superconductor with a topological twist

by Catherine Zandonella, Princeton University

Researchers at Princeton have discovered superconducting currents traveling along the outer edges of a superconductor with topological properties, suggesting a route to topological superconductivity that could be useful in future quantum computers. The superconductivity is represented by the black center of the diagram indicating no resistance to the current flow. The jagged pattern indicates the oscillation of the superconductivity which varies with the strength of an applied magnetic field. Credit: Stephan Kim, Princeton University

A discovery that long eluded physicists has been detected in a laboratory at Princeton. A team of physicists detected superconducting currents—the flow of electrons without wasting energy—along the exterior edge of a superconducting material. The finding was published in the May 1 issue of the journal Science.

The superconductor that the researchers studied is also a topological semi-metal, a material that comes with its own unusual electronic properties. The finding suggests ways to unlock a new era of "topological superconductivity" that could have value for quantum computing. (C.F. computing...)

"To our knowledge, this is the first observation of an edge supercurrent in any superconductor," said Nai Phuan Ong, Princeton's Eugene Higgins Professor of Physics and the senior author on the study.

"Our motivating question was, What happens when the interior of the material is not an insulator but a superconductor?" Ong said. "What novel features arise when superconductivity occurs in a topological material?"

Although conventional superconductors already enjoy widespread usage in magnetic resonance imaging (MRI) and long-distance transmission lines, new types of superconductivity could unleash the ability to move beyond the limitations of our familiar technologies.

Researchers at Princeton and elsewhere have been exploring the connections between superconductivity and topological insulators—materials whose non-conformist electronic behaviors were the subject of the 2016 Nobel Prize in Physics for F. Duncan Haldane, Princeton's Sherman Fairchild University Professor of Physics.

Topological insulators are crystals that have an insulating interior and a conducting surface, like a brownie wrapped in tin foil. In conducting materials, electrons can hop from atom to atom, allowing electric current to flow. Insulators are materials in which the electrons are stuck and cannot move. Yet curiously, topological insulators allow the movement of electrons on their surface but not in their interior.

To explore superconductivity in topological materials, the researchers turned to a crystalline material called molybdenum ditelluride, which has topological properties and is also a superconductor once the temperature dips below a frigid 100 milliKelvin, which is -459 degrees Fahrenheit.

"Most of the experiments done so far have involved trying to 'inject' superconductivity into topological materials by putting the one material in close proximity to the other," said Stephan Kim, a graduate student in electrical engineering, who conducted many of the experiments. "What is different about our measurement is we did not inject superconductivity and yet we were able to show the signatures of edge states."

The team first grew crystals in the laboratory and then cooled them down to a temperature where superconductivity occurs. They then applied a weak magnetic field while measuring the current flow through the crystal. They observed that a quantity called the critical current displays oscillations, which appear as a saw-tooth pattern, as the magnetic field is increased.

Both the height of the oscillations and the frequency of the oscillations fit with predictions of how these fluctuations arise from the quantum behavior of electrons confined to the edges of the materials.

Researchers have long known that superconductivity arises when electrons, which normally move about randomly, bind into twos to form Cooper pairs, which in a sense dance to the same beat. "A rough analogy is a billion couples executing the same tightly scripted dance choreography," Ong said.

The script the electrons are following is called the superconductor's wave function, which may be regarded roughly as a ribbon stretched along the length of the superconducting wire, Ong said. A slight twist of the wave function compels all Cooper pairs in a long wire to move with the same velocity as a "superfluid"—in other words acting like a single collection rather than like individual particles—that flows without producing heating.

If there are no twists along the ribbon, Ong said, all Cooper pairs are stationary and no current flows. If the researchers expose the superconductor to a weak magnetic field, this adds an additional contribution to the twisting that the researchers call the magnetic flux, which, for very small particles such as electrons, follows the rules of quantum mechanics.

The researchers anticipated that these two contributors to the number of twists, the superfluid velocity and the magnetic flux, work together to maintain the number of twists as an exact integer, a whole number such as 2, 3 or 4 rather than a 3.2 or a 3.7. They predicted that as the magnetic flux increases smoothly, the superfluid velocity would increase in a saw-tooth pattern as the superfluid velocity adjusts to cancel the extra .2 or add .3 to get an exact number of twists.

...

In molybdenum ditelluride and other so-called Weyl semimetals, this Cooper-pairing of electrons in the bulk appears to induce a similar pairing on the edges.

The researchers noted that the reason why the edge supercurrent remains independent of the bulk supercurrent is currently not well understood. Ong compared the electrons moving collectively, also called condensates, to puddles of liquid.

"From classical expectations, one would expect two fluid puddles that are in direct contact to merge into one," Ong said. "Yet the experiment shows that the edge condensates remain distinct from that in the bulk of the crystal."

The research team speculates that the mechanism that keeps the two condensates from mixing is the topological protection inherited from the protected edge states in molybdenum ditelluride. The group hopes to apply the same experimental technique to search for edge supercurrents in other unconventional superconductors.

"There are probably scores of them out there," Ong said.

The study, "Evidence for an edge supercurrent in the Weyl superconductor MoTe2," by Wudi Wang, Stephan Kim, Minhao Liu, F. A. Cevallos, Robert. J. Cava and Nai Phuan Ong, was published in the journal Science on May 1, 2020.

More at link:  https://phys.org/news/2020-04-supercurrent-edge-superconductor-topological.html

Weird superconductor leads double life

by Glennda Chui, SLAC National Accelerator Laboratory

Until about 50 years ago, all known superconductors were metals. This made sense, because metals have the largest number of loosely bound "carrier" electrons that are free to pair up and flow as electrical current with no resistance and 100 percent efficiency – the hallmark of superconductivity.

Then an odd one came along – strontium titanate, the first oxide material and first semiconductor found to be superconducting. Even though it doesn't fit the classic profile of a superconductor – it has very few free-to-roam electrons – it becomes superconducting when conditions are right, although no one could explain why.
https://phys.org/news/2018-03-weird-superconductor-life.html
Now scientists have probed the superconducting behavior of its electrons in detail for the first time. They discovered it's even weirder than they thought. Yet that's good news, they said, because it gives them a new angle for thinking about what's known as "high temperature" superconductivity, a phenomenon that could be harnessed for a future generation of perfectly efficient power lines, levitating trains and other revolutionary technologies.

The research team, led by scientists at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University, described their study in a paper published Jan. 30 in the Proceedings of the National Academy of Sciences.

"If conventional metal superconductors are at one end of a spectrum, strontium titanate is all the way down at the other end. It has the lowest density of available electrons of any superconductor we know about," said Adrian Swartz, a postdoctoral researcher at the Stanford Institute for Materials and Energy Science (SIMES) who led the experimental part of the research with Hisashi Inoue, a Stanford graduate student at the time.

"It's one of a large number of materials we call 'unconventional' superconductors because they can't be explained by current theories," Swartz said. "By studying its extreme behavior, we hope to gain insight into the ingredients that lead to superconductivity in these unconventional materials, including the ones that operate at higher temperatures."

Dueling Theories

According to the widely accepted theory known as BCS for the initials of its inventors, conventional superconductivity is triggered by natural vibrations that ripple through a material's atomic latticework. The vibrations cause carrier electrons to pair up and condense into a superfluid, which flows through the material with no resistance – a 100-percent-efficient electric current. In this picture, the ideal superconducting material contains a high density of fast-moving electrons, and even relatively weak lattice vibrations are enough to glue electron pairs together.

But outside the theory, in the realm of unconventional superconductors, no one knows what glues the electron pairs together, and none of the competing theories hold sway.

To find clues to what's going on inside strontium titanate, scientists had to figure out how to apply an important tool for studying superconducting behavior, known as tunneling spectroscopy, to this material. That took several years, said Harold Hwang, a professor at SLAC and Stanford and SIMES investigator.

"The desire to do this experiment has been there for decades, but it's been a technical challenge," he said. "This is, as far as I know, the first complete set of data coming out of a tunneling experiment on this material." Among other things, the team was able to observe how the material responded to doping, a commonly used process where electrons are added to a material to improve its electronic performance.

'Everything is Upside Down'

The tunneling measurements revealed that strontium titanate is the exact opposite of what you'd expect in a superconductor: Its lattice vibrations are strong and its carrier electrons are few and slow.

"This is a system where everything is upside down," Hwang said.

On the other hand, details like the behavior and density of its electrons and the energy required to form the superconducting state match what you would expect from conventional BCS theory almost exactly, Swartz said.

"Thus, strontium titanate seems to be an unconventional superconductor that acts like a conventional one in some respects," he said. "This is quite a conundrum, and quite a surprise to us. We discovered something that was more confusing than we originally thought, which from a fundamental physics point of view is more profound."

He added, "If we can improve our understanding of superconductivity in this puzzling set of circumstances, we could potentially learn how to harvest the ingredients for realizing superconductivity at higher temperatures." .........

More at link:  https://phys.org/news/2018-03-weird-superconductor-life.html

Strontium Titanate
A man-made diamond simulant also known as Fabulite, Diagem, Marvelite, Jewelite, and other trade names.
Author: Hobart M. King, Ph.D., GIA Graduate Gemologist

Strontium Titanate

Strontium Titanate: A faceted strontium titanate showing its very strong "fire" or "dispersion." Light that enters the stone is separated into its component colors, similar to a prism, and exits the stone in a scintillation of color. This stone is a 6-millimeter round weighing about 1.25 carats. The stone has a slightly purple body color that provides contrast to the dispersion.

What is Strontium Titanate?

Strontium Titanate is a man-made material with a chemical composition of SrTiO3. It grabbed public attention in the early 1950s as a diamond simulant - a material that has an appearance that is very much like diamond but has a different composition and/or crystal structure.

When cut and polished like a diamond, strontium titanate has a very similar luster, brilliance, and scintillation. However, strontium titanate has a "fire" that greatly exceeds the fire of a diamond. "Fire" is the ability of a gem to act as a prism and separate light passing through it into a rainbow of colors. The fire of strontium titanate is so strong that it immediately surprises the observer.
dispersion

A demonstration of dispersion: White light is separated into its component colors while passing through a prism. The "fire" of faceted stones like diamond and strontium titanate is produced by dispersion. NASA Image.

The Rise and Decline of Strontium Titanate

The impressive fire of strontium titanate made the stone a rapid success in the jewelry trade. People loved the intense fire and the lower price compared to diamond, and many purchased strontium titanate instead of diamond. Many people bought it just because they loved its appearance.

Savvy merchants invented exotic trade names for strontium titanate such as "Fabulite," "Diagem," "Marvelite," "Dynagem," and "Jewelite." The name "strontium titanate" was hard to remember and resembled the name of a "chemical." The trade names inspired a vision of beautiful stones and were easy for consumers to remember.

Between the early 1950s and the early 1970s, Fabulite, Diagem, and the other strontium titanate brands were popular sellers. Then, many people who purchased strontium titanate jewelry and wore it regularly began to notice that their stones were showing signs of wear. The facet faces were often scratched, and facet edges were often nicked and chipped. A material with a Mohs hardness of 5.5 does not stand up to wear like diamond with a hardness of 10, or ruby and sapphire with a hardness of 9.

https://geology.com/gemstones/strontium-titanate/