Finite-size-induced stability of a permanent magnet levitating over a superconductor in the Meissner state

摘要

The force between a magnetic dipole and a finite superconductor in the Meissner state (H < H_(cl)) is calculated by using an expression based on London's and Maxwell's equations. It demonstrates the existence of attractiveness and stability. The finiteness of a piece of superconductor therefore suffices to explain a stability for the levitation of a magnet over it or even the suspension of one of them under the other one. This does not contradict the existence of flux penetration. However, this makes the flux penetration not necessary to explain both stability and attractiveness, as has been assumed until now.