Beyond the gyrotropic motion: dynamic C-state in vortex spin torque oscillators

TL;DR

This paper explores a new dynamic C-state mode in vortex spin torque oscillators, revealing stochastic transitions from gyrotropic motion, with potential applications in neuromorphic computing.

Contribution

It introduces and characterizes a novel C-state mode in vortex STOs, supported by experiments and micromagnetic simulations, expanding understanding of their dynamic behaviors.

Findings

Identification of a stochastic transition between G and C-states

Experimental and simulation validation of the C-state dynamics

Potential for stochastic control in neuromorphic applications

Abstract

In the present study, we investigate a dynamical mode beyond the gyrotropic (G) motion of a magnetic vortex core in a confined magnetic disk of a nano-pillar spin torque nano oscillator. It is characterized by the in-plane circular precession associated to a C-shaped magnetization distribution. We show a transition between G and C-state mode which is found to be purely stochastic in a current-controllable range. Supporting our experimental findings with micromagnetic simulations, we believe that the results provide novel opportunities for the dynamic and stochastic control of STOs, which could be interesting to be implemented for example in neuromorphic networks.