It's called 'reddmatter', after a Star Trek reference.
https://metro.co.uk/2023/03/13/room-temperature-superconductor-could-make-hovering-trains-a-reality-18433402/?utm_source=dlvr.it&utm_medium=blogger
https://metro.co.uk/2023/03/13/room-temperature-superconductor-could-make-hovering-trains-a-reality-18433402/?utm_source=dlvr.it&utm_medium=blogger