Spin motive force induced by Rashba interaction in the strong sd coupling regime

TL;DR

This paper theoretically investigates the spin motive force induced by Rashba interaction under strong sd coupling, revealing two types of forces and their dependence on spin dynamics, with implications for experimental detection.

Contribution

It introduces a microscopic formalism to calculate the spin motive force in the strong sd coupling regime, identifying two distinct force components and their origins.

Findings

Two types of spin motive forces identified, proportional to different cross products.

Perpendicular component arises from spin relaxation in strong sd coupling.

Detection of AC voltage can serve as evidence of Rashba interaction.

Abstract

Spin motive force induced by the Rashba interaction in the presence of strong sd interaction between conduction electron and localized spin is theoretically studied. The motive force is calculated by evaluating the time-derivative of the current density on the basis of microscopic formalism. It is shown that there are two motive forces, one proportional to $\EvR\times\dot{\nv}$, the other, perpendicular component, proportional to $\EvR\times(\nv\times\dot{\nv})$, where $\EvR$ and $\nv$ are the Rashba electric field and localized spin direction, respectively. The second type arises in the strong sd coupling regime from the spin relaxation. The appearance of perpendicular component from the spin relaxation is understood from the analogy with the current-induced torques. In the case of domain wall motion, the two contributions to the spin motive force are the same order of magnitude, while the first term dominates in the case of precession of uniform magnetization. Our result explains appearance of the perpendicular component in the weak sd coupling limit, recently discussed in the context of spin damping monopole. Detection of AC voltage induced by the precession of uniform magnetization serves as a experimental evidence of the Rashba interaction in films and wires.