A skyrmion-based spin-torque nano-oscillator

TL;DR

This paper introduces a model for a spin-torque nano-oscillator utilizing the self-sustained gyration of magnetic skyrmions in a nanopillar, combining theoretical phenomenology and micromagnetic simulations.

Contribution

It presents a novel skyrmion-based oscillator model with detailed analysis of its dynamics and robustness against disorder, advancing spintronic device design.

Findings

Skyrmion gyration is driven by spin-transfer torques in a confined geometry.

Weak disorder does not significantly affect steady-state oscillations.

Quantitative micromagnetic simulations validate the phenomenological model.

Abstract

A model for a spin-torque nano-oscillator based on the self-sustained oscillation of a magnetic skyrmion is presented. The system involves a circular nanopillar geometry comprising an ultrathin film free magnetic layer with a strong Dzyaloshinkii-Moriya interaction and a polariser layer with a vortex-like spin configuration. It is shown that spin-transfer torques due to current flow perpendicular to the film plane leads to skyrmion gyration that arises from a competition between geometric confinement due to boundary edges and the vortex-like polarisation of the spin torques. A phenomenology for such oscillations is developed and quantitative analysis using micromagnetics simulations is presented. It is also shown that weak disorder due to random anisotropy variations does not influence the main characteristics of the steady-state gyration.