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MA: Fachverband Magnetismus

MA 5: Spincaloric Transport

MA 5.3: Vortrag

Montag, 14. März 2011, 11:30–11:45, HSZ 04

Ab initio calculations of spin caloritronics in magnetic tunnel junctions — Michael Czerner, Michael Bachmann, and •Christian Heiliger — I. Physikalisches Institut, Justus Liebig University Giessen, D-35392, Germany

The emerging research field of spin caloritronics [1] 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 of the magneto-thermoelectric power (MTEP) and of the spin-Seebeck coefficient in MgO based tunnel junctions with Fe and Co leads. In addition, the normal thermopower is calculated and gives for pure Fe and Co a quantitative agreement with experiments. Consequently, the calculated values in tunnel junctions are a good estimation of upper limits. In particular, spin-Seebeck coefficients of more than 100μV/K are possible. The MTEP ratio exceeds several 1000% and depends strongly on temperature. In the case of Fe leads the MTEP ratio diverges even to infinity at certain temperatures. The spin-Seebeck coefficient as a function of temperature shows a non-trivial dependence. For Fe/MgO/Fe even the sign of the coefficient changes with temperature.

[1] G. E. W. Bauer, A. H. MacDonald, and S. Maekawac, Solid State Comm. 150, 459 (2010).