Flux Trapping Effect: Magnetic Suspension & Levitation

[cartik]

Magnetic suspension and levitation is the caused by the flux trapping effect in superconductors.How does this flux get "trapped"?

Another quick question-
We link a magnet to a superconductor by bringing it very close to one ,until both of them start attracting and repelling. My question is, if the magnetic field strength of this magnet is greater than the critical field of the superconductor,the superconductor will lose its properties and become normal, instead of demonstrating magnetic levitation and suspension ,right ?

 

[K^2]

Without getting into details, Type II superconductor effectively has two critical field strengths. While there still exists the critical field under which the entire superconductor becomes normal conductor, above the lower of the thresholds, only small regions become normal. These regions form channels through the superconductor. Since the surface current can now exist in boundaries around these channels, magnetic flux can penetrate superconductor through these normal state channels. The magnetic flux in these channels becomes trapped.