Simulations of magnetic vortex dynamics in exchange-biased sub-micron-sized disks

Abstract

In this work we have investigated the influence of exchange bias coupling in the magnetic vortex dynamics of sub-micrometer bilayer disk by means of a series of micromagnetic simulations. The hysteresis simulations showed that the vortex stability increases with the coupling constant. In relaxation simulations, it was observed that the gyrotropic movement has a variable frequency that increases with time, which is not observed when exchange bias is absent. Under a rotating magnetic field acting on the disks, the critical velocity for vortex polarity reversion increases with the coupling constant and frequency. Our results show that the critical velocity can be adjusted in a wide range by selecting the magnetic coupling constant and the oscillating frequency, i.e., it would be possible to control the critical velocity for vortex polarity inversion through the exchange bias coupling.