> All you need a chunk of type 2 superconductor, a strong magnet, and some liquid nitrogen.
This isn't entirely accurate. A "chunk of type 2 superconductor" would just show the Meissner Effect, which is different than "flux pinning". The Meissner Effect is how superconductors essentially repel magnetic fields, resulting in levitation; it wouldn't necessarily pin the levitating body in-place such that it could follow some track for example.
Flux pinning occurs when some magnetic fields penetrate the superconductor in discrete "tubes" through the imperfections (along the grains) of the superconductor. In order for flux pinning to happen, you must have an extremely thin superconductor (in the case of the video, it's actually a sapphire crystal wafer with a 1-micron thick coating of superconductor ceramic material).
EDIT: Technically, you could also get flux pinning if you were to supercool the superconductor (i.e. make it a superconductor) while it's in the magnetic field of the magnet.
I played quite a bit with the Meissner and the Flux pinning effect. But I was never able to change a flux pinning "on the fly". You always had to reheat the superconductor to something over the transition temperature and then cool it down again inside a magnetic field (in the desired position). But then, it was quite strongly locked in that position and would snap back to where it was when moved.
So, I'm quite curious on how this works ;) Is it because it's a very thin superconductor in this video?
Just to do (dia)magnetic levitation, you could put together 4 cubes of neodymium magnets, then cleave a very thin sheet of pyrolytic graphite and gently suspend it on top of the cubes.
This isn't entirely accurate. A "chunk of type 2 superconductor" would just show the Meissner Effect, which is different than "flux pinning". The Meissner Effect is how superconductors essentially repel magnetic fields, resulting in levitation; it wouldn't necessarily pin the levitating body in-place such that it could follow some track for example.
Flux pinning occurs when some magnetic fields penetrate the superconductor in discrete "tubes" through the imperfections (along the grains) of the superconductor. In order for flux pinning to happen, you must have an extremely thin superconductor (in the case of the video, it's actually a sapphire crystal wafer with a 1-micron thick coating of superconductor ceramic material).
EDIT: Technically, you could also get flux pinning if you were to supercool the superconductor (i.e. make it a superconductor) while it's in the magnetic field of the magnet.