Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 5: Spincaloric Transport

MA 5.2: Vortrag

Montag, 14. März 2011, 11:15–11:30, HSZ 04

Experimental Study of the Anisotropic Magneto-Seebeck Effect in (Ga,Mn)As Thin Films — Matthias Althammer¹, Alexander T. Krupp¹, Thomas Brenninger¹, Deepak Venkateshvaran¹, Matthias Opel¹, Lukas Dreher², Wladimir Schoch³, Wolfgang Limmer³, Rudolf Gross¹, and •Sebastian T. B. Goennenwein¹ — ¹Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching, Germany — ²Walter Schottky Institut, Technische Universität München, Garching, Germany — ³Abteilung Halbleiterphysik, Universität Ulm, Ulm, Germany

In analogy to anisotropic magnetoresistance (AMR), the thermopower of ferromagnetic materials also characteristically depends on the orientation of the magnetization vector. This anisotropic magneto-thermopower – or anisotropic magneto-Seebeck effect (AMS) – has only scarcely been studied to date. Taking the ferromagnetic semiconductor (Ga,Mn)As with its large magneto-resistive effects as a prototype example, we have measured the evolution of both the AMR and the AMS effects at liquid He temperatures as a function of the orientation of a magnetic field applied in the (Ga,Mn)As film plane, for different, fixed magnetic field magnitudes. Our data show that the AMS effect can be adequately modeled only if the symmetry of the (Ga,Mn)As crystal is explicitly taken into account. We will quantitatively compare our AMR and AMS measurements with corresponding model calculations, and address the validity of the Mott relations linking the magneto-resistance and the magneto-Seebeck coefficients.