THEORY OF ENHANCED PROXIMITY EFFECT BY THEEXCHANGE FIELD IN FS BILAYERS

摘要

Enhanced proximitiy effect in normal metal / insulator / diffusive ferromagnet / insulator/ superconductor (N/I/DF/I/S) junctions is studied for various situations solving theUsadel equation under the Nazarov's generalized boundary condition. Conductance ofthe juntion and density of states of the DF are calculated by changing the magnitude ofthe resistance, Thouless energy and the exchange field in DF. We heve clarified that dueto the enhanced proximity effect, a sharp zero bias conductance peak (ZBCP) appearsfor small Thouless energy while a broad ZBCP appears for large Thouless energy. Themagnitude of this ZBCP can exceed its value for normal states in contrast to the ZBCPobserved in diffusive normal metal / superconductor junctions. We find structures similarto the conductance in the density of states.