Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 51: Transport: Nanoelectronics II - Spintronics and Magnetotransport (jointly with HL and MA)

TT 51.9: 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.