Voltage dependence of Landau-Lifshitz-Gilbert damping of a spin in a current driven tunnel junction

TL;DR

This paper develops a theoretical model describing how the damping of a localized spin in a tunnel junction depends on applied voltage, highlighting the linear relationship influenced by particle-hole asymmetry.

Contribution

It introduces a voltage-dependent damping model for a localized spin in a tunnel junction, emphasizing the role of lead asymmetry and energy-dependent density of states.

Findings

Damping $ ext{α}$ varies linearly with voltage.

Particle-hole asymmetry controls the damping behavior.

Energy dependence of density of states influences damping.

Abstract

We present a theory of Landau-Lifshitz-Gilbert damping $\alpha$ for a localized spin ${\vec S}$ in the junction coupled to the conduction electrons in both leads under an applied volatege $V$. We find the voltage dependence of the damping term reflecting the energy dependence of the density of states. We find the effect is linear in the voltage and cotrolled by particle-hole asymmetry of the leads.