Domain-wall dynamics driven by thermal and electrical spin-transfer torque

According to spin Seebeck effect, a thermal spin current will be produced when a temperature gradient is ap-plied to the metallic ferromagnet. Similar to the electrical spin transfer torque (ESTT) induced by spin-polarized current, there is also a thermal spin transfer torque (TSTT) caused by the thermal spin current, which can be attributed to the s-d interaction between the conduction electrons and the local magnetization. In this paper, the generalized analytical expressions of thermal spin current and TSTT are derived based on the spinor Boltzmann equation (SBE) under the local equilibrium approximation. This generalized TSTT has different terms compared to the previous phenomenological form, and the phenomenological coefficients can be determined theoretically within our framework. Combined with the SBE under the applied electric field and temperature gradient, we solve the Landau-Lifshitz-Gilbert-Levy equation to study the domain wall (DW) motion driven by the ESTT and TSTT. We investigated the temperature-dependent DW motion, the total spin torque, and TSTT in permalloys. We found that the velocity of the DW can be promoted by increasing temperature and temperature gradient, which provide a path to effectively utilize the Joule heating in spintronics devices.

Automated summary

In this study, the generalized analytical expressions of thermal spin current and thermal spin transfer torque (TSTT) are derived based on the spinor Boltzmann equation under the local equilibrium approximation. The different terms and theoretically determinable phenomenological coefficients of the TSTT were analyzed. The Landau-Lifshitz-Gilbert-Levy equation was then solved to investigate the influence of TSTT on domain wall motion, revealing that increasing temperature and temperature gradient can enhance the velocity of domain walls.