Spin transfer torque on magnetic insulators

TL;DR

This paper uses first-principles calculations to accurately estimate the spin transfer torque at metal-insulator interfaces, resolving previous conflicting estimates and providing insights into the spin mixing conductance of silver-YIG interfaces.

Contribution

It provides the first-principles calculation of the spin mixing conductance for silver and YIG interfaces, clarifying the magnitude and nature of spin transfer torque in these systems.

Findings

Real part of spin mixing conductance is dominant.

Conductance magnitude is around 10^14 Ω^-1m^-2.

Interface behavior can be explained by a local spin model.

Abstract

Recent experimental and theoretical studies focus on spin-mediated heat currents at interfaces between normal metals and magnetic insulators. We resolve conflicting estimates for the order of magnitude of the spin transfer torque by first-principles calculations. The spin mixing conductance G^\uparrow\downarrow of the interface between silver and the insulating ferrimagnet Yttrium Iron Garnet (YIG) is dominated by its real part and of the order of 10^14 \Omega^-1m^-2, i.e. close to the value for intermetallic interface, which can be explained by a local spin model.