Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 52: Poster II - Magnetic Heusler compounds, Magnetic shape memory alloys, Thin Films, Micro-/Nano-structured magnetic materials, Graphene, Spins in organics, Magnetic imaging, Surface Magnetism, Spin excitations/Torque, Spincaloric transport

MA 52.63: Poster

Freitag, 30. März 2012, 11:00–14:00, Poster A

Barrier thickness dependence of the Magneto Seebeck effect in magnetic tunnel junctions: Ab initio studies — •Michael Czerner and Christian Heiliger — I. Physikalisches Institut, Justus Liebig Universität Giessen, D-35392, Germany

The magneto Seebeck effect is the dependence of the thermopower in a magnetic tunnel junction on the relative orientation of both magnetic layers [1]. First calculations show that there is a non-trivial barrier thickness dependence of this effect [1]. Therefore, we systematically investigate the thermopower for parallel and antiparallel alignment of the magnetic leads in MgO based tunnel junctions. We show that the actual dependence on the MgO thickness also depends on the magnetic material of the leads. Our theoretical investigations are ab initio calculations based on density functional theory. In particular, we used the Korringa-Kohn-Rostoker and the non-equilibrium Green's function method to obtain the transmission function T(E). Using T(E), we calculated in linear response the transport coefficients, e.g. conductance, Seebeck coefficient, thermal conductance (electronic contribution) [2]. Additionally we study the thermopower as a function of the tilting angle between the magnetization of the two ferromagnetic leads.

[1] M. Walter, J. Walowski, V. Zbarsky, M. Münzenberg, M. Schäfers, D. Ebke, G. Reiss, A. Thomas, P. Peretzki, M. Seibt, J. S. Moodera, M. Czerner, M. Bachmann, C. Heiliger, Nature Materials 10, 742 (2011)

[2] M. Czerner, M. Bachmann, C. Heiliger, Phys. Rev. B 83, 132405 (2011)