UPDATE: Hyun Tak Kim has put out news slides that describes a semiconductor and superconductor phase for LK99. He quoted his own paper on VO2 to explain that most researchers did not understand the difference between MIT and MST (MIT, metal to insulator transition: after cooling down, the resistivity jump → becomes very large; MST, transition from metal to superconductor: resistivity jump after cooling down → becomes very small).
1. Princeton – Magnetic Materials, Not Superconductors with Arxiv 1 preprint of announcement from 2 days ago.
2. University of PUC-Rio, Brazil – “Analyzed Model (Theoretical Calculations)”. Arxiv 2.
Berry curvature and quantum metric in copper-substituted lead phosphate apatite (Wei Chen)
Be it superconducting or not, we show that the normal state of this material has peculiar quantum geometrical properties that may be related to the magnetism and the mechanism for flat band superconductivity. Based on a recently proposed spinless two-band tight-binding model for the Pb-Cu hexagonal lattice subset of the crystalline structure, which qualitatively captures the two flat bands in the band structure, we elaborate the highly anisotropic Berry curvature and quantum metric in the regions of Brillouin zone where one flat band is above and the other below the Fermi surface. In these regions, the Berry curvature has a pattern in the planar momentum that remains unchanged along the out-of-plane momentum. Moreover, the net orbital magnetization contributed from the Berry curvature is zero, signifying that the magnetism in this material should come from other sources. The quantum metric has a similar momentum dependence, and its two planar components are found to be roughly the same but the out-of-plane component vanishes, hinting that the superfluid stiffness of the flat band superconductivity, shall it occur, may be quite anisotropic.
3. Peking University – “One Theoretical Computing Paper”. Arxiv 3
Superconducting materials with high critical temperature have the potential to revolutionize many fields, including military, electronic communications, and power energy. Therefore, Scientists around the world have been tirelessly working with the ultimate goal of achieving high temperature superconductivity. In 2023, a preprint by S. Lee et al in South Korea claimed the discovery of ultra-high-temperature superconductivity with a critical temperature of up to 423 K in Cu-doped lead-apatite (LK-99) (arXiv:2307.12008, arXiv:2307.12037), which caused a worldwide sensation and attention. Herein, the electronic structures, phonon dynamics, and electrical conductivities of LK-99 and its parent compound lead-apatite have been calculated using first-principles methods. The results show that the lead-apatite compound and the LK-99 compound are insulator and half-metal respectively. The flat band characteristic is consistent with previous calculations. The electrical conductivity of LK-99 compound shows two extreme point, and the electrical conductivity along the C-axis increases significantly after 400 K. The phonon dispersion spectra of the compounds were investigated, demonstrating their dynamic instability.
4. University of Illinois “Need to synthesize Cu2S-free LK-99 to verify superconductivity” Arxiv 4.
Phase transition of copper (I) sulfide and its implication for purported superconductivity of LK-99
LK-99 must be synthesized without any Cu2S to allow unambiguous validation of the superconducting properties of LK-99.
5. The Indian team is suspected to have leaked a new video “in the video is another sample, but ferromagnetic”
6. Douyin user Newton’s re-engraving results of the flame laser sword (seems to be ferromagnetic)
7. Arxiv 5 – Kunming Institute of Physics and Engineering – “Electronic Structure Computational Paper”
Ferromagnetic ground state and Spin-orbit coupling induced bandgap open in LK99
Our calculations cannot determine whether LK99 is a superconductor, but provide some clues and suggestions for its flat band properties.
8. Arxiv 6 – Max Planck Institute – “Density Functional Theory Simulation Computation Paper”
Wannier functions, minimal model and charge transfer in Pb9CuP6O25
“We computed the maximum projected Wannier function from density functional theory simulations and constructed a minimal two-orbital triangular lattice model containing a copper (3dxz, 3dyz) substrate, and a copper (3dxz, 3dyz) and oxygen ( 2px, 2py) four-orbital twisted honeycomb model of the substrate. Since the Coulomb interaction Ud is much larger than the potential energy difference between copper and oxygen, charge transfer will occur when the hole filling fraction nh > 1. We further calculated the interaction parameter , and the possible insulating states and corresponding spin-exchange couplings are discussed.”
9. Awana VPS Indian team thinks yesterday’s levitating sample is not superconducting but composite magnetic.
10. Quantum Energy Research Institute changed the nature of the company and applied for a trademark
The original Korean researchers have changed their company from a research and development company to a manufacturing company.
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for general comprehension,
a recommended current density for copper is estimated ~95 A/mm2 (absolute value on temperature range?), if designing conductors of ‘every’ diameter,
within electronics (e.g. CPU’s power connections) Copper ~100-1000A/mm2 or experimental results from Graphene nanoribbons (~THz FETs) ~10⁵-10*10⁶A/mm2
BSCCO (SC type 2, Tc 33K_Bi2201-104K_Bi2234, no rare-earth elements) “Typical tapes of 4 mm width and 0.2 mm thickness support a current of 200 A at 77 K, giving a critical current density in the Bi-2223 filaments of 5 kA/mm2. This rises markedly with decreasing temperature so that many applications are implemented at 30–35 K, even though Tc is 108 K.”
YBCO (SC type 2, TC ~93K, first above 77K)
Why do lossless superconductor wires have current density restrictions (relative? with approaching Tc)?
What is a reference diagram for pure copper metal superconductor (type1 ?) around Tc being reference to superconducting crystals&compounds at higher temperatures? (Thx)
“Why do lossless superconductor wires have current density restrictions (relative? with approaching Tc)?”
Since there’s a finite charge carrier density, (which is usually lower than that in metals to begin with,) the current must be carried by the motion of electrons, and the higher the current, the faster the electrons must move. This implies that as the current density increases, so does the kinetic energy of the electrons.
Superconductivity is due to the electrons forming “Cooper pairs” indirectly bound to each other by interaction with the structure of the superconductor. Essentially any time one of the electrons in a pair runs into an obstacle, the kinetic energy ends up transferred to the other electron in the pair, so there’s no loss.
At a high enough current, the kinetic energy of the electrons’ motion exceeds the bonding energy of the Cooper pairs, (Which is in turn very low.) and instead of being traded back and forth, the energy breaks up the Cooper pair, and the electrons stop acting in a superconducting fashion.
“… and then you’re screwed …”, for the local heating produced by the now-not-inhibited kinetic energy nucleates further Cooper pair collapses in a rather geometric fashion, leading to bulk superconductivity collapse. The inductive ‘momentum’ of all the superconducting conductor’s Cooper paired electrons then turns into ohmic heating at the point of collapse, almost always resulting in a spectacular deflagration of the superconducting wire. It fuses. And no longer may be coerced into superconduction. End of story, time to buy new superconducting magnet coils.
Typically superconducting wire is made from strands of superconductor in a normal conductor matrix, so that in the event of a “quench” event, the matrix carries the current. The quench tends to propagate through the wire fairly rapidly, so the ohmic heating is usually well distributed.
If things are designed properly, anyway…
What about adding super chemistry to the mix?
I have heard it said that molecules can act like discrete atoms…maybe coax this substance into rings. Been hearing a lot about the “demon:”
https://www.livescience.com/physics-mathematics/bizarre-demon-particle-found-inside-superconductor-could-help-unlock-a-holy-grail-of-physics
Thanks for Your explanations.
There are exceptions to metals being superconductors at low temperatures (e.g. copper, silver, gold, platinum etc.), while being within best electricity conductors at room temperatures. (‘bulk’ carbon (amorphous, graphite, diamond) is no superconductor, carbon nanotubes are type 2 SC, Tc ~12-15K)
“the strength of interaction between the lattice structure and the valence electrons are too weak” inside these metals for establishing Cooper pairs of electrons
(since copper is no superconducting metal at low temperatures)
“What is a reference diagram for pure aluminum metal superconductor (type1 ?) around Tc being reference to superconducting crystals&compounds at higher temperatures?”
e.g. ‘https://journals.aps.org/prb/article/10.1103/PhysRevB.99.094506/figures/2/medium’
All the theoretical modeling papers about “flat bands” in lead-copper apatite coming out of the woodwork is suspicious – as if they had that stuff on the shelf. Is this software so parametric already that detailed electronic analysis crystal lattice physics has a one-week turn-around?
Regardless…
Just a dumb passing thought – knowing very little about allotropes (diamond, plutonium)…
Might the higher energy state of having the copper atom in the desired, but energetically disfavored location that causes the 0.4% contraction become more like a ground state if the molten concoction was solidified under extreme pressure? Most everything is soft at 925C, and the crystal likely has a normal (positive) expansion coefficient, so there might not be a simple way to heat/cool it in an anvil. Just thinking that if you compressed it 0.4%, you might get the allotrope to form?
I’m still fantasizing the material might have some interesting electronic properties…. I consumed way to much “science” about this stuff last week to let go (like Brian).
There are ready-to-go software tools for the DFT analysis and other relevant calculations and simulations. You probably just enter the structure you want to examine, some additional input parameters, and which stuff you want it to calculate, and it does most of the work.