A recent report of room temperature superconductivity at ambient pressure in Cu-substituted apatite (‘LK99’) has invigorated interest in the understanding of what materials and mechanisms can allow for high-temperature superconductivity. Here I perform density functional theory calculations on Cu-substituted lead phosphate apatite, identifying correlated isolated flat bands at the Fermi level, a common signature of high transition temperatures in already established families of superconductors. I elucidate the origins of these isolated bands as arising from a structural distortion induced by the Cu ions and a chiral charge density wave from the Pb lone pairs. These results suggest that a minimal two-band model can encompass much of the low-energy physics in this system. Related: Korean Team Claims To Have Created The First Room-Temperature, Ambient-Pressure Superconductor
- Date Posted:
- August 1, 2023
The BOJ’s low interest policy remains an anchor of global bond yields, but that anchor will soon be set at a higher level. U.S. bonds will appear even more unattractive to Japanese investors, whose exit from the market would allow U.S. bond yields to drift higher. The eventual Fed rate cuts would reduce FX hedging costs and potentially bring back some Japanese investors, but until then it looks like one more marginal source of demand is evaporating even as Treasury supply is set to increase. This suggests that Treasury yields will continue to drift higher.