Magnetoresistance in a ferromagnet/d-wave-superconductor double tunnel junction

N. Yoshida; Y. Tanaka; J. Inoue; S. Kashiwaya

doi:10.1103/PhysRevB.63.024509

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Magnetoresistance in a ferromagnet/d-wave-superconductor double tunnel junction

N. Yoshida, Y. Tanaka, J. Inoue, S. Kashiwaya

DOI 10.1103/PhysRevB.63.024509 · Physical Review B

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Abstract

Spin-dependent transport in ferromagnet/d-wave-superconductor/ferromagnet double tunnel junctions is studied theoretically. When the magnetization axis of the ferromagnets is antiparallel, with the increase of the bias voltage, the magnitude of the pair potential is suppressed and becomes zero at a critical voltage VC due to the pronounced imbalance of the nonequilibrium spin density. Under the existence of the zero-energy state at the interface of the d-wave superconductor, the magnitude of the quasiparticle current through the junction is enhanced as compared to that in the normal state. The resulting tunneling magnetoresistance shows an anomalous voltage dependence which cannot be expected for the conventional superconductor double junctions.