Berlin 2015 – scientific programme
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MA: Fachverband Magnetismus
MA 29: Spincaloric Transport II (jointly with TT)
MA 29.2: Talk
Wednesday, March 18, 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)