Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 35: Postersession Transport: Nanoelectronics, Quantum Coherence and Quantum Information, Fluctuations and Noise

TT 35.9: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

A Microscopic Model of Current-Induced Switching of Magnetization — •Niko Sandschneider and Wolfgang Nolting — AG Festkörpertheorie, Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin

We study the behaviour of the magnetization in a ferromagnetic metal/nonmagnetic insulator/ferromagnetic metal/paramagnetic metal (FM1/NI/FM2/PM) tunnel junction. It is calculated self-consistently within the nonequilibrium Keldysh formalism. The magnetic regions are treated as band ferromagnets, such as Co, and are described by the single-band Hubbard model. The left (FM1) and right (PM) lead are assumed to remain in equilibrium. We developed a nonequilibrium spectral density approach to solve the Hubbard model approximately in the switching magnet FM2. By applying a voltage to the junction it is possible to switch between antiparallel (AP) and parallel (P) alignment of the magnetizations of the two ferromagnets. The transition from AP to P occurs for positive voltages while the inverse transition from P to AP can be induced by negative voltages only. This behaviour is in agreement with the Slonczewski model[1] of current-induced switching and appears self-consistently within the model, i.e. without using half-classical methods like the Landau-Lifshitz-Gilbert equation.

[1] J. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996)