Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 5: Spindependent Transportphenomena I

MA 5.3: Vortrag

Montag, 25. Februar 2008, 10:45–11:00, H 0112

Tunneling magnetoresistance and tunneling anisotropic magnetoresistance in ferromagnet/semiconductor/ferromagnet tunnel junctions — •Alex Matos-Abiague and Jaroslav Fabian — Institue for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany

We investigate transport properties of asymmetric ferromagnet/semiconductor/ferromagnet tunnel junctions. We show that in such structures both the tunneling magnetoresistance (TMR) and anisotropic tunneling magnetoresistance (TAMR) effects can coexist. Three different terms contribute to the total magnetoresistance. The dominant contribution corresponds to the TMR which depends on the relative but not on the absolute magnetization directions in the ferromagnets. Conversely, the TAMR contribution is determined by the absolute orientation of the magnetization in one of the ferromagnets [1]. A third mixed contribution exhibits a dependence on both relative and absolute magnetization orientations. This contribution, like the TAMR, originates from the interference of Rashba and Dresselhaus spin-orbit couplings at the ferromagnet/semiconductor interfaces [1,2]. Model calculations for Fe/GaAs/Fe tunnel junctions are presented. Furthermore, based on rather general considerations, we present a simple model that reveals the magnetoresistence dependence on the absolute and relative magnetization directions in the ferromagnets. [This work was supported by the DFG through SFB 689]

[1] J. Moser et al., Phys. Rev. Lett. 99, 056601 (2007).

[2] J. Fabian et al. Acta Phys. Slov. 57, 565 (2007).