Enhancement of spin mixing conductance by $s$-$d$ orbital hybridization in heavy metals

TL;DR

This paper investigates how $s$-$d$ orbital hybridization in heavy metals enhances the spin-mixing conductance at magnetic interfaces, which is crucial for spin transfer and spin pumping in magnetic multilayers.

Contribution

It introduces a generalized Anderson model to quantify the impact of $s$-$d$ orbital hybridization on spin-mixing conductance, revealing an increase in its magnitude.

Findings

Orbital hybridization increases spin-mixing conductance.

The generalized Anderson model effectively describes $s$-$d$ hybridization effects.

Enhanced spin transfer efficiency in magnetic multilayers.

Abstract

In a magnetic multilayer, the spin transfer between localized magnetization dynamics and itinerant conduction spin arises from the interaction between a normal metal and an adjacent ferromagnetic layer. The spin-mixing conductance then governs the spin-transfer torques and spin pumping at the magnetic interface. Theoretical description of spin-mixing conductance at the magnetic interface often employs a single conduction-band model. However, there is orbital hybridization between conduction $s$ electron and localized $d$ electron of the heavy transition metal, in which the single conduction-band model is insufficient to describe the $s$-$d$ orbital hybridization. In this work, using the generalized Anderson model, we estimate the spin-mixing conductance that arises from the $s$-$d$ orbital hybridization. We find that the orbital hybridization increases the magnitude of the spin-mixing conductance.