Dresden 2014 – scientific programme
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MA: Fachverband Magnetismus
MA 39: Focus Session: Unconventional Spin Structures (jointly with DS)
MA 39.4: Topical Talk
Thursday, April 3, 2014, 11:15–11:45, BEY 118
Commensurability and chaos in magnetic vortex oscillations — •Joo-Von Kim1, Sébastien Petit-Watelot1, Antonio Ruotolo2,3, Rubén Otxoa1, Karim Bouzehouane2, Julie Grollier2, Arne Vansteenkiste4, Ben Van de Wiele5, Vincent Cros2, and Thibaut Devolder1 — 1Institut d'Electronique Fondamentale, UMR CNRS 8622, Univ. Paris-Sud, 91405 Orsay, France — 2Unité Mixte de Physique CNRS/Thales and Univ. Paris-Sud, 1 av. A. Fresnel, 91767 Palaiseau, France — 3Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong — 4Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, B-9000 Ghent, Belgium — 5Department of Electrical Energy, Systems and Automation, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent, Belgium
In spin-torque driven vortex oscillations in small nanocontacts, periodic reversal of the vortex core appear above a critical current and results in a self-modulation phenomenon involving gyration and relaxation oscillations. By tuning the ratio between the gyration frequency and the rate of core reversal, we show that commensurate phase-locked and incommensurate chaotic states are possible, resulting in Devil's staircases with driving currents. This represents a novel dynamical regime for vortex dynamics in which the gyrotropic dynamics is self-modulated by the periodic core reversal.