The actual picture of (poor) levitation in the paper you linked is pretty compelling. This isn’t a complex, noisy measurement showing something that’s related to superconductivity — this is a magnet and a supposed superconductor repelling each other.
As far as I know, that’s possible with permanent magnets (and it would be weird, but not impossible, if the group instead synthesized a novel ferromagnet and didn’t notice), electrets (seems pretty unlikely here), very extreme amounts of static charge (again, seems unlikely), and actual superconductivity (would be awesome).
Random bits of cooked oxides, ceramics, and such don’t float on a magnet.
As far as I know, that’s possible with permanent magnets (and it would be weird, but not impossible, if the group instead synthesized a novel ferromagnet and didn’t notice), electrets (seems pretty unlikely here), very extreme amounts of static charge (again, seems unlikely), and actual superconductivity (would be awesome).
Random bits of cooked oxides, ceramics, and such don’t float on a magnet.