Regensburg 2013 – scientific programme
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MA: Fachverband Magnetismus
MA 8: Spin Excitations and Spin Torque
MA 8.4: Talk
Monday, March 11, 2013, 10:15–10:30, H23
Spin Torque Ferromagnetic Resonance in MgO-based Magnetic Tunnel Junctions — •Yuriy Aleksandrov1,2, Alina M. Deac1, Kerstin Bernert1,2, Ciaran Fowley1, Volker Sluka1, Ewa Kowalska1, Jürgen Lindner1, and Jürgen Fassbender1,2 — 1HZDR, Dresden, Germany — 2TU Dresden, Dresden, Germany
Spin polarized currents can exert a torque on a ferromagnetic layer‘s magnetic moment leading to switching or steady-state precession. Spin-torque driven ferromagnetic resonance (ST-FMR) is a unique method to measure the magnetic anisotropy, saturation magnetization and damping in a nanoscale structure. ST-FMR can also be used to determine the bias dependence of spin-transfer torques in magnetic tunnel junctions [1- 3]. For different values of applied RF power and DC bias, we swept the RF frequency from 1 to 15 GHz and measured the resulting mixing voltage across our MgO-based tunnel junctions. Not only the low-frequency fundamental mode was observed, but also a higher order mode. We find that the mixing voltage peak shifts with applied DC-field and increases with RF power. Finally, we separate the field-like torque contribution from that of the in-plane spin-transfer torque and determine their bias dependence.
[1] A. Deac et al., Nature Phys. 4, 803 (2008).
[2] H. Kubota et al., Nature Phys. 4, 37 (2008).
[3] J. C. Sankey et al., Nature Phys. 4, 67 (2008).