Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 30: Spin-Torque Phenomena

MA 30.4: Vortrag

Mittwoch, 9. März 2016, 10:45–11:00, H33

Spin-orbit torques in L1₀-FePt/Pt thin films from first principles: effect of impurities — •Guillaume Géranton, Bernd Zimmermann, Frank Freimuth, Nguyen H. Long, Phivos Mavropoulos, Stefan Blügel, and Yuriy Mokrousov — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Spin-orbit torque (SOT) is an attractive way of manipulating the magnetization in spintronic devices. While the intrinsic contributions to the SOT have been investigated in the last years [1], little is known about the extrinsic contributions, i.e. the torques arising in the presence of impurities. Using the ab initio Boltzmann formalism, we compute the current-induced SOT in L1₀-FePt/Pt thin films in the presence of impurities. The transition rates between electronic states are obtained from the microscopic scattering rates computed from first principles [2]. This goes significantly beyond the standard description of extrinsic SOTs, which is usually based on the constant relaxation-time approximation [3]. We show the crucial dependence of the SOT on the distribution of impurities at the interface, demonstrate that a large part of the SOT is mediated by spin currents and observe a large spin accumulation in the Pt layers.

We gratefully acknowledge funding under the SPP 1538 programme of DFG.

[1] F. Freimuth et al., Phys. Rev. B 90, 174423 (2014).

[2] N. H. Long et al., Phys. Rev. B 90, 064406 (2014).

[3] G. Géranton et al., Phys. Rev. B 91, 014417 (2015).