Sign of the crossed conductances at a ferromagnet/superconductor/ferromagnet double interface

[摘要] Crossed conductance in hybrid ferromagnet/superconductor/ferromagnet (FSF) structures results from the competition between normal transmission and Andreev reflection channels. Crossed Andreev reflection (CAR) and elastic cotunneling (EC) between the ferromagnets are dressed by local Andreev reflections, which play an important role for transparent enough interfaces and intermediate spin polarizations. This modifies the simple result previously obtained at lowest order, and can explain the sign of the crossed resistances in a recent experiment [D. Beckmann , cond-mat/0404360]. This holds both in the multiterminal hybrid structure model (where phase averaging over the Fermi oscillations is introduced by hand within the approximation of a single nonlocal process) and for infinite planar interfaces (where phase averaging naturally results in the microscopic solution with multiple nonlocal processes).

[发布日期] 2004-11-01

[关键词] ANDREEV REFLECTION;MICROSCOPIC THEORY;SUPERCONDUCTOR;METAL;TRANSPORT;FERROMAGNETS;EXCITATIONS