Magnetic vortex states in chromium(IV) oxide (CrO2)

Abstract

As an exploration for probable magnetic vortex state in chromium(IV) oxide (CrO2), we performed micro-magnetic simulations on CrO2 nanodiscs. For our simulation studies, we considered CrO2 nanodiscs with 100 nm diameter and 20 nm thickness. After the ferromagnetic positive or negative saturation, when the applied magnetic field along the ±x-axis was reduced, vortex states with its magnetization winding in xy-plane nucleated in the CrO2 nanodisc at ∓12 mT, and annihilated at ∓41 mT. The magnetic vortex states were found to be stable even after reducing the applied magnetic field to 0 mT. Further, switching the magnetic vortex core polarity pointing up to down and vice versa using DC as well as AC magnetic fields has been simulated. The magnetization of the vortex core instantaneously flipped by an applied DC magnetic field of ±138 mT and within 2 ns by applied 6 GHz resonance AC magnetic field with 8 mT amplitude. Furthermore, we present a comparison about the formation, remanent state and switching of the magnetic vortex state in CrO2 nanodisc with that of the most widely studied permalloy nanodisc having same dimensions.