Dresden 2011 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 38: Magnetization Dynamics IV
MA 38.1: Vortrag
Mittwoch, 16. März 2011, 14:45–15:00, HSZ 403
Monitoring Vortex Dynamics and Vortex Core Polarization with Magnetic Tunnel Junctions — •Hermann Stoll1, Matthias Noske1, Karsten Rott2, Markus Sproll1, Matthias Kammerer2, Michael Curcic1, Bartel Van Waeyenberge3, Günter Reiss2, and Gisela Schütz1 — 1MPI für Metallforschung, Stuttgart — 2Universität Bielefeld — 3Ghent University, Belgium
Nakano et al. [1] have shown, that a magnetic tunnel junction (MTJ) placed on a micron-sized vortex element is capable of detecting gyrotropic motion and vortex core polarization when the vortex is excited by an ac current. However, problems occurred by crosstalk between the excitation current and the MTJ output. We have virtually eliminated this drawback by taking advantage of a sophisticated lock-in technique. In that way we would like to demonstrate a 1 bit vortex V(ortex)MRAM - with electric write and read-out - where data is stored in the out-of-plane magnetization of the vortex core, showing up or down - in a Permalloy vortex structure, 0.5 microns in diameter. In addition, our technique allows us to perform table-top experiments on vortex dynamics and vortex core reversal and can replace microscopic techniques (e.g., X-ray or MFM microscopy) in many cases. We will proof this in a second example where we have measured the frequency and amplitude dependence of the gyrotropic eigenmode of a vortex structure in an external static magnetic field. We will compare our findings with similar results [2] achieved by Magnetic Resonance Force Microscopy (MRFM). [1] K. Nakano et al., Applied Physics Express 3 (2010) 053001 [2] P. Pigeau et al., APL 96, 132506 (2010)