Generation of non-equilibrium spin-motive force at the surface of a topological insulator induced by current-driven domain wall motion in the magnetic substrate

TL;DR

This paper develops a generalized theoretical method to analytically compute the spin-motive force at topological insulator surfaces caused by current-driven domain wall motion in magnetic substrates, expanding previous approaches.

Contribution

The authors extend the unitary transformation method to systems with spin-momentum coupling, enabling analytical calculation of spin-motive force in topological insulators.

Findings

Analytical expression for spin-motive force at topological insulator surfaces.

Extension of the unitary transformation approach to spin-momentum coupled systems.

Demonstration of non-equilibrium spin-motive force generation due to domain wall motion.

Abstract

The generalized Faraday method can be used for computation of spin-motive force (SMF) within the unitary transformation approach. Meanwhile, the unitary transformation approach, which could be employed to obtain an effective collinear exchange interaction of non-collinear magnetic structures, cannot be used when the other parts of the Hamiltonian contain spin-dependent couplings. In the current study, the method of unitary transformation has been generalized to systems with spin-momentum coupling. In this way, the SMF at topological insulator surfaces has been computed analytically.