日 時：2010年9月21日(火曜日) 14:00-
場 所：工学部６号館１階 大会議室（１０３号室）
講 師：Prof.Achim Rosch
(Institut fuer Theoretische Physik, Universitaet zu Koeln)
題 目：”Skyrmion lattices and spin torques in chiral magnets“
In chiral magnets the interplay of spin-orbit interactions and thermal fluctuations lead to the formation of a lattice of magnetic vortices, so called Skyrmions. These topological defects have been directly observed by neutron scattering and, more recently, by Lorentz transmission electron microscopy. The Berry phase associated to the winding number of the Skyrmions leads both to a topological Hall effect for the conduction electrons and to forces on the Skyrmion lattice in the presence of a current. This topological mechanism leads to a very efficient coupling of the spin currents to the magnetic structure resulting in critical currents which are 5-6 orders of magnitude smaller than those observed in typical spin torque experiments.