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Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 20: Transport: Spincaloric Transport (jointly with MA)

TT 20.2: Talk

Monday, March 11, 2013, 15:15–15:30, H22

Tunnel magneto-Seebeck effect in high temperature gradients — •Marvin Walter1, J. C. Leutenantsmeyer1, V. Zbarsky1, T. Eggebrecht1, M. Münzenberg1, K. Rott2, A. Böhnke2, G. Reiss2, A. Thomas2, M. Czerner3, and C. Heiliger31I. Phys. Inst., Universität Göttingen, Germany — 2Dept. of Physics, Bielefeld University, Germany — 3I. Phys. Inst., Universität Giessen, Germany

CoFeB/MgO/CoFeB devices showing a giant TMR effect are possible candidates for the generation of spin-currents by thermal heating and the tunnel magneto-Seebeck effect was already observed. It is theoretically predicted that for a 3 monolayer MgO barrier the torque of the spin-polarized tunneling electrons might be sufficient to observe thermal spin transfer torque (T-STT).

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 with thicknesses down to 3 monolayers. The MTJs are heated by a Ti:Sa femtosecond laser to achieve high temperature gradients. The heating of the MTJ by a femtosecond laser is simulated using finite element methods. Using the parameters observed in the experimental setup, the simulations show temperature differences across the MgO barrier of more than 10K for a duration in the order of picoseconds. This temperature difference should be sufficient to achieve T-STT. Furthermore, the thermomagnetoelectric properties in high temperature gradients of MTJs with perpendicular magnetic anisotropy and switching current densities of 2· 105 A/cm2 are investigated.

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