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MA: Fachverband Magnetismus
MA 50: Joint Session "Spincaloric Transport" (jointly with TT)
MA 50.1: Vortrag
Freitag, 30. März 2012, 09:30–09:45, EB 301
Magneto-Seebeck Effect in Magnetic Tunnel Junctions — •Marvin Walter1, Jakob Walowski1, Vladyslav Zbarsky1, Markus Münzenberg1, Markus Schäfers2, Daniel Ebke2, Günter Reiss2, Andy Thomas2, Patrick Peretzki3, Michael Seibt3, Michael Czerner4, Michael Bachmann4, and Christian Heiliger4 — 1I. Phys. Inst., Uni Göttingen, Germany — 2Dept. of Physics, Bielefeld University, Germany — 3IV. Phys. Inst., Uni Göttingen, Germany — 4I. Phys. Inst., Uni Giessen, Germany
We present the observation of a magneto Seebeck effect in CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs). The effects could be used for thermal spin-injection and thermally driven spin-transfer torque. The samples presented in this work consist of a minimal pseudo-spin-valve stack with sputtered Ta and CoFeB layers and an e-beam evaporated MgO barrier. The MTJs are heated by either a diode laser or a Ti:Sa femtosecond laser for higher powers. The laser is focused onto the sample in a confocal microscope setup. The heating is simulated by finite element methods and the experimental results are compared with ab-initio calculations of the magneto-thermoelectric power and of the spin-Seebeck coefficient. A magneto-Seebeck effect of up to 40% is found for higher laser powers and a theoretically predicted sign change of the thermal voltage is observed. The experimental data and the temperature simulations are in good agreement with the ab-initio calculations. In addition, time-resolved reflectivity and autocorrelation measurements in a pump-probe setup are carried out.