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TT: Fachverband Tiefe Temperaturen

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

TT 20.10: Vortrag

Montag, 11. März 2013, 17:30–17:45, H22

Thermal spin-transfer torques in magnetic tunnel junctions — Michael Czerner, Christian Franz, and •Christian Heiliger — I.Physikalisches Institut, Justus Liebig University Giessen, D-35392, Germany

The emerging research field of spin caloritronics combines the spin-dependent charge transport with energy or heat transport. In comparison to thermoelectrics the spin degree of freedom is considered as well. We present ab initio calculations based on density functional theory using a Green's function KKR method. We compute the non-equilibrium density in a non-collinear regime, which allows us to calculate the spin-transfer torque. In our investigation we focus on the material dependence of the thermal spin-transfer torque in MgO based tunnel junctions. In particular, we investigate Fe, Co, and FeCo alloys as lead materials. The FeCo alloy is described by the coherent potential approximation (CPA) including vertex corrections for the non-equilibrium density. The thermal spin-transfer torque is calculated for several barrier thicknesses. It turns out that the size of the thermal spin-transfer torque is orders of magnitude smaller than spin-transfer torque at an applied bias voltage. Consequently, the thermal spin-transfer torque can be utilized only for very thin barrier thicknesses.