SKM 2021 – scientific programme
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MA: Fachverband Magnetismus
MA 11: Posters Magnetism III
MA 11.28: Poster
Wednesday, September 29, 2021, 13:30–16:30, P
Bipolar Spin Hall Nano-Oscillators — •Toni Hache1, Yancheng Li2, Tillmann Weinhold3, Bernd Scheumann1, Francisco T. J. Goncalves1, Olav Hellwig1, 4, Jürgen Fassbender1, 3, and Helmut Schultheiss1, 3 — 1Helmholtz-Zentrum Dresden-Rossendorf, Germany — 2Johns Hopkins University, United States — 3Technical University Dresden, Germany — 4Technical University Chemnitz, Germany
Spin Hall nano-oscillators (SHNO) convert dc currents in microwave oscillations of the magnetization. The frequency can be tuned by external magnetic fields, the applied dc current magnitude or by injection locking if an additional microwave magnetic field is applied to the SHNO. Here, we demonstrate another approach to extend the frequency range of an SHNO by adding a second ferromagnetic layer. An SHNO with a layer stack NiFe/Pt/CoFeB is used. By applying a charge current a pure spin current is generated by the spin Hall effect in the Pt. It has opposite spin polarization at both interfaces being in contact with the ferromagnetic layers. Therefore, only in one of both the Gilbert damping can be compensated by the spin-orbit torque to achieve auto-oscillations. By switching the charge current polarity the spin current polarizations switch as well and the second ferromagnetic material shows auto-oscillations. In this way two frequency ranges can be accessed by switching the applied charge current. The authors acknowledge financial support from the Deutsche Forschungsgemeinschaft within programme SCHU 2922/1-1.