Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 50: Spincaloric Transport (jointly with TT)
MA 50.6: Vortrag
Donnerstag, 23. März 2017, 11:00–11:15, HSZ 403
Pumping laser excited spins through MgO barriers — •Ulrike Martens1, Jakob Walowski1, Thomas Schumann1, Maria Mansurova1, Alexander Boehnke2, Torsten Huebner2, Guenter Reiss2, Andy Thomas3, and Markus Muenzenberg1 — 1Institut für Physik, EMAU Greifswald, Germany — 2CSMD, Physics Department, Bielefeld University, Germany — 3Institute for Metallic Materials, IFW Dresden, Germany
We present a study of the tunnel magneto-Seebeck (TMS) effect in MgO based magnetic tunnel junctions (MTJs). The electrodes consist of CoFeB with in-plane magnetic anisotropy. The temperature gradients which generate a voltage across the MTJs layer stack are created using laser heating. Using this method, the temperature can be controlled on the micrometer length scale: here, we investigate, how both, the TMS voltage and the TMS effect, depend on the size, position and intensity of the applied laser spot. For this study, a large variety of different temperature distributions was created across the junction. We recorded two-dimensional maps of voltages generated by heating in dependence of the laser spot position and the corresponding calculated TMS values. The voltages change in value and sign, from large positive values when heating the MTJ directly in the centre to small values when heating the junction on the edges and even small negative values when heating the sample away from the junction. Those zero crossings lead to very high calculated TMS ratios.
Funding by DFG SPP 1538 is acknowledged