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MA: Fachverband Magnetismus

MA 55: Poster II

MA 55.14: Poster

Freitag, 4. April 2014, 10:30–13:30, P2

Large tunnel magneto-Seebeck effect in Co2FeSi Heusler compound — •Alexander Boehnke¹, Marvin Walter², Christian Sterwerf¹, Michael Czerner³, Karsten Rott¹, Andy Thomas¹, Christian Heiliger³, Markus Münzenberg², and Günter Reiss¹ — ¹Thin Films and Physics of Nanostructures, Bielefeld University, Germany — ²I. Physikalisches Institut, Georg-August-Universität Göttingen, Germany — ³I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Germany

Heusler compounds are promising candidates for magnetic tunnel junctions (MTJ) as their potential high spin polarization leads to high tunnel magnetoresistance (TMR) ratios. Recently the tunnel magneto-Seebeck effect (TMS), that occurs when a temperature gradient is applied to an MTJ, has gained much interest. Our measurements show that Heusler compounds can give a good thermoelectric readout contrast, which is beneficial for future applications in, e.g., green information technology.

We investigated Co₂FeSi/MgO/Co₇₀Fe₃₀ MTJs. Interestingly, the TMS ratio (96 %) is comparable to the TMR ratio (101 %). Similar effects were found for Al₂O₃ barrier MTJs, but both observations differ from CoFeB/MgO/CoFeB MTJs, where the TMS is much smaller than the TMR. This reveals a strong influence of the contributing transport bands on the TMS, basically different from the TMR. Further ab initio calculations are pending to gain a proper understanding of these fundamental effects.