Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 48: Magnetization / Demagnetization Dynamics IV
MA 48.4: Vortrag
Donnerstag, 19. März 2015, 15:45–16:00, EB 301
Electrical determination of vortex state in sub-micron magnetic elements — •Ajay Gangwar1,2, Hans G. Bauer1, Jean-Yves Chauleau1, Matthias Noske2, Markus Weigand2, Hermann Stoll2, Gisela Schütz2, and Christian H. Back1 — 1Institut für Experimentelle Physik, Universität Regensburg, Germany — 2Max-Planck-Institut für Intelligente Systeme, Stuttgart, Germany
Magnetic vortices, characterized by two boolean topological quantities: chirality (c) and polarity (p), are currently under close scrutiny [1]. We have studied vortex dynamics excited by spin transfer torque and found that the vortex states can be detected electrically by analyzing homodyne voltage signals generated by the anisotropic magneto-resistance (AMR) effect [2]. An in-plane external dc magnetic field is required to rectify the homodyne signal which can be measured with a nano-voltmeter. The sign of this DC voltage changes with the handedness (+cp or -cp) of the vortex state which makes the AMR effect a promising technique to investigate vortex states electrically. In addition, the vortex dynamics was also observed by direct imaging in a Scanning Transmission X-ray Microscope in order to verify the measured AMR signal, in particular its correct range of power and frequency. Our experimental results have found to be consistent with micromagnetic simulations which gives us a better understanding of the experimental outcome and proofs the validity of the AMR technique. [1] M. Kammerer et al., Nature Commun. 2, 279 (2011). [2] M. Goto et al., PRB 84, 064406 (2011).