A unified first-principles study of Gilbert damping, spin-flip diffusion and resistivity in transition metal alloys

TL;DR

This paper presents a first-principles scattering theory approach to calculate resistivity, spin-flip diffusion length, and Gilbert damping in transition metal alloys, accurately matching experimental data for permalloy.

Contribution

It introduces a unified first-principles method that simultaneously accounts for disorder and spin-orbit coupling to compute key magnetic and transport properties.

Findings

Calculated resistivity, spin-flip diffusion length, and Gilbert damping for NiFe alloys.

Results closely match experimental low-temperature measurements.

The formalism effectively captures dominant contributions to these parameters.

Abstract

Using a formulation of first-principles scattering theory that includes disorder and spin-orbit coupling on an equal footing, we calculate the resistivity $\rho$, spin flip diffusion length $l_{sf}$ and the Gilbert damping parameter $\alpha$ for Ni$_{1-x}$Fe$_x$ substitutional alloys as a function of $x$. For the technologically important Ni$_{80}$Fe$_{20}$ alloy, permalloy, we calculate values of $\rho = 3.5 \pm 0.15$ $\mu$Ohm-cm, $l_{sf}=5.5 \pm 0.3$ nm, and $\alpha= 0.0046 \pm 0.0001$ compared to experimental low-temperature values in the range $4.2-4.8$ $\mu$Ohm-cm for $\rho$, $5.0-6.0$ nm for $l_{sf}$, and $0.004-0.013$ for $\alpha$ indicating that the theoretical formalism captures the most important contributions to these parameters.