Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 73: Spincaloric Transport II (jointly with MA)

TT 73.2: Vortrag

Mittwoch, 18. März 2015, 15:15–15:30, H 0110

Bias-enhanced tunnel magneto-Seebeck effect in Co-Fe-B/MgO-based magnetic tunnel junctions — •Marvin von der Ehe¹, Alexander Boehnke², Marius Milnikel¹, Ulrike Martens¹, Vladyslav Zbarsky¹, Karsten Rott², Andy Thomas², Michael Czerner³, Günter Reiss², Christian Heiliger³, and Markus Münzenberg¹ — ¹Inst. f. Phys., Universität Greifswald, Germany — ²CSMD, Physics Dep., Bielefeld University, Germany — ³I. Phys. Inst., Universität Giessen, Germany

In recent spincaloritronic research, several groups have observed the tunnel magneto-Seebeck effect (TMS) in magnetic tunnel junctions (MTJs) incorporating CoFe electrodes and MgO tunnel barriers [1,2].

Here, we present an approach of tuning the TMS effect by applying a DC bias voltage to the MTJ while a temperature gradient is generated by laser heating. We prepared Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions that show high TMR ratios and observed Seebeck voltages of several microvolt, generated locally in the MTJ layers. Our experiments show that the resulting thermocurrent can be tuned to exhibit an on/off- switching when the magnetization configuration of the electrodes is changed from parallel to antiparallel and vice versa. Consequently, very high bias-enhanced TMS ratios are obtained. This behavior can be understood by the interplay of the TMS effect and the ohmic properties of the MTJs for small voltages. Funding by DFG SPP 1538 is acknowledged.

[1] Walter, M., et al. Nature Mater. 10, 742 (2011)

[2] Liebing, N., et al. Phys. Rev. Lett. 107, 177201 (2011)