paper

Spin-Transfer Torque and Magnetoresistance in Superconducting Spin-Valves

arXiv:0905.3171 · doi:10.1103/PhysRevB.79.224504

Abstract

We study the spin-transfer torque and magnetoresistance of a ferromagnetsuperconductorferromagnet spin-valve, allowing for an arbitrary magnetization misorientation and treating both s-wave and d-wave symmetries of the superconductor. We take fully into account Andreev reflection and also the spin-triplet correlations that are generated when the magnetizations are non-collinear. It is found that the torque and magnetoresistance are both strongly enhanced when topological zero-energy states are present at the interfaces, which is the case for d-wave superconductors with a crystallographic orientation of [110] relative to the interface (-wave symmetry). Moreover, we find that the magnetoresistance displays a strong oscillatory and non-monotonous behavior as a function of where and are the interlayer width of the superconducting region and the superconducting coherence length, respectively. This feature is also attributed to the crossover from layers of size to layers of size , where the contribution to transport from zero-energy states gradually vanishes.

10 pages, 7 figures. Accepted for publication in Phys. Rev. B

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