How do you explain the almost three orders of magnitude drop in resistance in Fig. 6d in one of the original articles ( https://arxiv.org/pdf/2307.12037.pdf ) with a few LK-99 particles sprinkled here an there? There must be a current path along which more than 99.8% of the material is in the supposed superconducting state. So the particles almost touch but not quite yet?
I think the more likely explanation is that the particles do touch each other but the interface is not superconductive. In other words, it is a polycrystalline material, and most of it is LK-99, but the grain boundaries are not a very good conductor. In conventional superconductors grain boundaries don't disrupt superconductivity because they are 3D superconductors, but in this allegedly 1D superconductor the superconducting channels in most cases don't meet at the grain boundaries, so the current has to overcome the resistance of some material that is almost an insulator.
If that is the case it will be difficult to produce a material that is macroscopically superconducting. But I hope researchers will be able to make single crystals that are large enough for resistance measurements so that finally it can be determined if this material is a superconductor or not. For practical uses the best result that can be achieved with this material may be a metal-LK-99 composite where the LK-99 particles lower the resistivity of the metal by 50-90%.
I think the more likely explanation is that the particles do touch each other but the interface is not superconductive. In other words, it is a polycrystalline material, and most of it is LK-99, but the grain boundaries are not a very good conductor. In conventional superconductors grain boundaries don't disrupt superconductivity because they are 3D superconductors, but in this allegedly 1D superconductor the superconducting channels in most cases don't meet at the grain boundaries, so the current has to overcome the resistance of some material that is almost an insulator.
If that is the case it will be difficult to produce a material that is macroscopically superconducting. But I hope researchers will be able to make single crystals that are large enough for resistance measurements so that finally it can be determined if this material is a superconductor or not. For practical uses the best result that can be achieved with this material may be a metal-LK-99 composite where the LK-99 particles lower the resistivity of the metal by 50-90%.