The rectilinear motion of the individual asymmetrical skyrmion driven by temperature gradients

Abstract

Engineering the dynamic motion of the bubble-like magnetic skyrmion exhibits great potential in the application of spintronics. Especially, as a natural property, temperature plays an important role in the skyrmion motion. For example, the non-linear motion and the random Brownian motion of skyrmions driven by temperature gradient induced spin-transfer torque and temperature fluctuation have been explored respectively. However, due to the limitation of existing hypothesis-based simulation methods, the study of the motion of individual skyrmion in temperature gradient from the perspective of the thermodynamic free energy is absent, and its kinematic equation is unclear. Here, we employed a temperature-related phase field model to demonstrate the rectilinear motions of an individual skyrmion in temperature gradients. And the thermodynamics analysis reveals that the temperature gradient induced energy imbalance of both sides of skyrmions is the driving force of skyrmion motions. Furthermore, a kinematic equation is proposed to describe the skyrmion motion in temperature gradients. Therefore, this study provides the thermodynamics mechanism and kinematic equation for skyrmion rectilinear thermal motions, which is anticipated to be the theoretical guidance for further research about dynamics of skyrmions and its potential applications in functional devices.