Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 18: Spincaloric Transport
(Joint session of MA and TT organized by MA)
TT 18.3: Vortrag
Montag, 7. März 2016, 15:30–15:45, H31
Tunnel magneto-Seebeck effect in MgO tunnel junctions — •Ulrike Martens1, Alexander Boehnke2, Marvin von der Ehe1, Christian Franz3, Michael Czerner3, Karsten Rott2, Andy Thomas2,4, Christian Heiliger3, Günter Reiss2, and Markus Münzenberg1 — 1Institut für Physik, Ernst-Moritz-Arndt Universität Greifswald, Germany — 2CSMD, Physics Department, Bielefeld University, Germany — 3Justus-Liebig-Universität Gießen, Germany — 4IMW, IFW Dresden, 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]. Semiconducting materials are known to have large Seebeck coefficients. This is mainly attributed to the gap in their band structure and the asymmetric position of the Fermi-level. The tunnel magneto-Seebeck effect (TMS) is a powerful tool to investigate such spin-dependent Seebeck coefficients, because separate spin-channels can be defined in magnetic tunnel junctions (MTJs). Here, we investigate the spin-dependent Seebeck coefficients of CoFeB/MgO/CoFeB MTJs with different thicknesses of the MgO barrier. CoFeB/MgO/CoFeB MTJs with TMR ratios of 80% to 230% show TMS ratios of 5% to 50%. With a size variation of the heating laser spot we see zero crossing voltage compensation effects. 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)
[3] A. Boehnke et al. Rev.Sci. Instrum 84 (2013)