Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 101: Transport: Nanoelectronics II - Spintronics and Magnetotransport (jointly with TT, MA)
HL 101.9: Talk
Friday, March 30, 2012, 11:45–12:00, BH 243
Rotating skyrmion lattices by spin torques and field gradients — •Karin Everschor1, Markus Garst1, Benedikt Binz1, Christian Pfleiderer2, and Achim Rosch1 — 1Institute for Theoretical Physics, University of Cologne, Germany — 2Physics-Department E21, Technical University Munich, Germany
Chiral magnets like MnSi form lattices of skyrmions, i.e. magnetic whirls, which react sensitively to small electric currents. The interplay of these currents and thermal gradients can induce either a rotation of the magnetic pattern by a finite angle or -- for higher current densities or larger gradients -- a steady rotation defined by a constant angular velocity. We develop a theory of rotational forces induced by gradients in magnetic field or temperature. Reactive forces (Magnus and Lorentz forces) arise from Berry phases while several mechanisms affect the dynamics of magnets by damping. We use the Landau Lifshitz Gilbert equation extended by extra damping terms in combination with a phenomenological treatment of pinning forces to develop a theory of the relevant rotational torques.