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HL: Fachverband Halbleiterphysik
HL 19: Spin controlled transport I
HL 19.4: Vortrag
Dienstag, 27. März 2007, 11:30–11:45, H14
Tunneling Anisotropic Magnetoresistance and Spin-Orbit Coupling in tunnel structures with single-crystal GaAs barriers — •Michael Lobenhofer1, Jürgen Moser1, Eva Brinkmeier1, Alex Matos-Abiague2, Dieter Schuh1, Werner Wegscheider1, Jaroslav Fabian2, and Dieter Weiss1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93040 Regensburg — 2Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg
We report the observation of tunneling anisotropic magnetoresistance effect (TAMR) in tunnel structures with single-crystal GaAs barriers. A stack of Fe, GaAs and Au, with iron grown epitaxially on the GaAs tunnel barrier, shows pronounced spin-valve-like signatures. Measurements of the tunneling resistance in a constant high in-plane magnetic field show a uniaxial anisotropy depending on the direction of the saturated magnetization of the iron layer. Depending on the bias voltage the high resistance state is either observed for the magnetization M oriented in [110] or in [-110] direction. This is the first observation of a TAMR effect in sandwiches involving a conventional ferromagnet like iron. We propose a theoretical model in which the C2v symmetry, resulting from the interference of Bychkov-Rashba and Dresselhaus spin-orbit interactions, is transferred to the tunnelling probability, giving rise to the two-fold symmetry observed in the TAMR experiments.