Bias-field control of the Neel skyrmion nonlinearity in a confined nanostructure

We study the nonlinear dynamics of a cylindrical skyrmion-based oscillator within the framework of a generalized Thiele model. We demonstrate the influence of an bias magnetic field applied perpendicular to the plane of the nanocylinder on the oscillation frequency and on the nonlinearity coefficient. It is shown that the field tunes the response frequency, while also producing a substantial change in the nonlinear frequency shift. We find that the nonlinearity coefficient reverses its sign as the field crosses a certain critical value. The variation of the nonlinearity coefficient with the field is clearly illustrated by the observed qualitative changes in nonlinear amplitude-frequency responses. Controlling the nonlinear properties of a skyrmion oscillator by changing the bias magnetic field opens up prospects for creating tunable computational elements for neuromorphic applications.