Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 48: Poster Session II
MA 48.45: Poster
Donnerstag, 10. März 2016, 15:00–18:00, Poster B1
Spin-Transfer-Torque in Magnetic Tunnel Junctions — •Christian Denker1, Jakob Walowski1, Ulrike Martens1, Vladislav Zbarksi2, Günter Reiss3, and Markus Münzenberg1 — 1Institut für Physik, Ernst-Moritz-Arndt Universität, Greifswald, Germany — 2Fakultät für Physik, Georg-August Universität, Göttingen, Germany — 3CSMD, Physics Department, Universität Bielefeld, Germany
Magnetic tunnel junctions based on MgO symmetry filtering allow specific control of the electronic structure and are appealing for THz spintronics.
Our optimized MgO/CoFeB based layer stack with perpendicular tunnel junction shows a minimal critical switching of only 9.3 kA/cm2. This is partly associated with a thermally activated switching probability and specific switching distribution [1]. We found the enhanced demagnetization observed by He et al. [2] and a distinct selection of electrons tunneling through the MgO barrier by switching parallel and antiparallel magnetization for varied anisotropy values along a wedge sample in pump-probe spectroscopy with fs excitation. We show that different effects on time scales related to energy-momentum distribution of hot electrons, which relax within 70 fs, determine the THz currents in samples with barrier thickness of only 2 monolayers MgO. This will eventually allow a spin transfer of the hot electrons into the second CoFeB layer even on a ps time scale.
[1] Leutenantsmeyer et al., Mater. Trans., 9, 56 (2015)
[2] He et al. Sci. Rep. 3, 2883 (2013)