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MA: Fachverband Magnetismus
MA 37: Spin Torque and Spin Excitations I
MA 37.7: Talk
Thursday, April 3, 2014, 11:15–11:30, HSZ 401
Spin-orbit torques in magnetic nanostructures with structural inversion asymmetry — •Roberto Lo Conte1,3, Ales Hrabec2, Andrei Mihai2, Tomek Schulz1, Thomas Moore2, and Mathias Kläui1,3 — 1Institute of Physics, Johannes Gutenberg University, Staudingerweg 7, 55128 Mainz, Germany — 2School of Physics and Astronomy, University of Leeds, LS2 9JT, U.K. — 3Graduate School Material Science in Mainz (MAINZ), Staudingerweg 9, 55128 Mainz, Germany
Intense investigations are carried out on novel magnetic materials systems with perpendicular magnetic anisotropy (PMA) and structure inversion asymmetry (SIA). So called spin-orbit torques (SOTs) have been observed in PMA nanostructures with SIA when an electric current is injected, leading to ultra-fast current-induced domain wall motion (CIDWM) and current-induced magnetization switching [1,2]. We investigate CIDWM in PMA-nanowires made of Ta/CoFeB/MgO and Pt/CoFeB/MgO by Kerr Microscopy. By measuring the effect of an in-plane external magnetic field on the DWM, we determine the acting torques. At sufficiently large longitudinal fields we observed a strong change in the DW velocity, of different sign for the two types of DWs. This demonstrates that Néel-type DWs maximize the acting torques and that the chirality of the DWs is fixed by the Dzyaloshinskii-Moriya interaction (DMI) generated at the interfaces [3,4]. We determine the strength of the DMI-effective field and we find that in combination with the spin Hall effect in Ta and Pt, this leads to efficient wall motion in opposite directions for Ta and Pt underlayers.