A frequency-controlled magnetic vortex memory

Abstract

Using the ultralow damping NiMnSb half-Heusler alloy patterned into vortex-state magnetic nanodots, we demonstrate a concept of nonvolatile memory controlled by the frequency. A perpendicular bias magnetic field is used to split the frequency of the vortex core gyrotropic rotation into two distinct frequencies, depending on the sign of the vortex core polarity $p=\pm 1$ inside the dot. A magnetic resonance force microscope and microwave pulses applied at one of these two resonant frequencies allow for local and deterministic addressing of binary information (core polarity).