2020/07/09 by Mehrnia, Mahdi, Trimble, Jeremy, Heinonen, Olle +1
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · doi:10.48550/arxiv.2007.05015
Because of its stability, the polarity of a magnetic vortex core (VC) is a candidate for binary data storage. Switching can be accomplished, e.g, by driving the VC above a critical velocity vc. Here, we report on controlled and repeated switching of VC polarity by significantly reducing vc locally. We excite vortex dynamics in thin Permalloy disks with a magnetic field pulse, and map the two-dimensional VC trajectory using time-resolved Kerr microscopy. In pristine samples, we observe normal gyrotropic motion of the VC. After laser-induced generation of defects, however, we observe repeated VC reversal at much-reduced critical velocities as low as 20 m/s. Micromagnetic simulations reveal how local reduction of exchange coupling can create VC reversal sites for deterministic VC switching.