Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 9: Spin Excitations/Spin Torque
MA 9.10: Vortrag
Montag, 16. März 2015, 18:00–18:15, H 0112
Current-induced spin torque resonance of a magnetic insulator — •Michael Schreier1,2, Takahiro Chiba3, Arthur Niedermayr1,2, Johannes Lotze1,2, Hans Huebl1,4, Stephan Geprägs1, Saburo Takahashi3, Gerrit E. W. Bauer3,5,6, Rudolf Gross1,2,4, and Sebastian T. B. Goennenwein1,4 — 1Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching, DE — 2Physik-Department, TU München, Garching, DE — 3Institute for Materials Research, Tohoku University, Sendai, JP — 4Nanosystems Initiative Munich, DE — 5WPI Advanced Institute for Materials Research, Tohoku University, Sendai, JP — 6Kavli Institute of NanoScience, Delft University of Technology, Delft, NL
We report the observation of spin transfer torque induced ferromagnetic resonance in the ferromagnetic insulator yttrium iron garnet (YIG). An alternating current at gigahertz frequencies in the Pt layer of a YIG/Pt sample generates Oersted and effective anti damping (spin transfer) torque fields inducing ferromagnetic resonance in the YIG. This can be observed as DC spin pumping and spin Hall magnetoresistance rectification voltages. To disentangle the two excitation and detection processes we investigate YIG layers of different thickness, which impacts the magnitude of the effective damping torque field. In ultrathin yttrium iron garnet films the magnitude of the spin transfer torque actuated magnetization dynamics is substantially enhanced and dominates that generated by the Oersted field. We discuss the determination of spurious effects and present a quantitative analysis. Support by the DFG through SPP1538 is gratefully acknowledged.