Regensburg 2016 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 18: Spincaloric Transport
(Joint session of MA and TT organized by MA)
TT 18.4: Talk
Monday, March 7, 2016, 15:45–16:00, H31
Spincaloric properties of epitaxial Co2MnSi/MgO/Co2MnSi magnetic tunnel junctions — •Benjamin Geisler1,2 and Peter Kratzer2 — 1FRM II, Technische Universität München, 85748 Garching, Germany — 2Fakultät für Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany
Magnetic tunnel junctions (MTJs) with ferromagnetic, half-metallic electrodes are interesting spintronics devices due to their high tunnel magnetoresistance ratio. If a thermal gradient is applied to such a MTJ, the relative electrode magnetization can be detected by measuring the induced voltage, i.e., by exploiting the magneto-Seebeck effect.
Here we present an ab initio viewpoint on transport and spincaloric properties of epitaxial Co2MnSi/MgO(001)/Co2MnSi MTJs [Phys. Rev. B 92, 144418 (2015)]. We compare results calculated with the conventional Sivan-Imry approach to results obtained from solving the Landauer-Büttiker equation directly. The latter procedure circumvents the linear response approximation inherent in the Seebeck coefficient and provides the response of the system (current or voltage) to arbitrary thermal gradients. Moreover, thermal variations of the chemical potential in the leads and finite-bias effects can be readily included in this method. Especially the former are found to be important here for obtaining qualitatively correct results. We show how the spincaloric properties of the MTJs depend on the interface atomic structure and that they can be tailored by a targeted growth control. Finally, we shortly comment on the influence of thermally activated electrode phonons and interface magnons.