Strong Skyrmion Oscillations Driven by Spatially Dependent Spin Current

Abstract

Nanoscale spintronic oscillators have attracted research interest in recent years because of their potential application in neuromorphic computing. Sustainable magnetization precession or gyrotropic motion of a skyrmion triggered by spin-polarized current or spin current gives rise to spintronic oscillation. However, the amplitude of skyrmion oscillation is exceedingly small. In this work, we report a skyrmion oscillation with a much larger amplitude based on periodical deformation of the skyrmion in a region with geometric confinement. This periodical deformation is induced by spatial-dependent spin current and is relevant to the skyrmion Hall effect. The amplitude and period of the oscillation can be well manipulated by modifying the damping coefficient, the slope of spin-current density, and the dimension of medium. The characteristic frequency of skyrmion oscillation determined by fast Fourier transformation is split under an external magnetic field that breaks the symmetry for the oscillation in the left and right parts of the skyrmion. This work paves the way to develop nanoscale skyrmion oscillators with tunable frequency and amplitude for neuromorphic computing.