Meissner effect

This so-called critical current behavior and the Meissner effect are the two key features of superconductors.

The levitation, the scientists said, demonstrated the Meissner effect, which ensures zero magnetic field inside a superconductor.

One such test is for the Meissner effect: because a superconductor expels magnetic fields, it repels other magnets, producing an iconic levitating effect.

The South Korean researchers provided a video of what they say is LK-99 exhibiting the Meissner effect, but superconductors aren’t the only things that float above magnets—graphite, for example, also levitates.

That phenomenon, known as the Meissner effect, is considered to be definitive evidence of a superconductor.