ANDREEV STATES AND SPONTANEOUS SPIN CURRENTS IN SUPERCONDUCTOR-FERROMAGNET PROXIMITY SYSTEMS

摘要

The proximity effect between a ferromagnet and a superconductor is examined within the framework of the self-consistent Bogoliubov de Gennes equations. It is shown that for a thin ferromagnetic layer on a semi-infinite superconductor, a spontaneous supercurrent may flow parallel to the interface. The current turns on or off repeatedly as a function of the exchange splitting, E_(ex) for a fixed thickness film, d. It is shown that the current state is stabilized by a lowering of the total quasiparticle kinetic energy, and this is interpreted in terms of the Andreev bound states in the ferromagnetic layer.