First-principles calculation of the Gilbert damping parameter via the linear response formalism with application to magnetic transition-metals and alloys

TL;DR

This paper introduces a first-principles linear response method within a relativistic band structure framework to calculate the Gilbert damping parameter, accounting for thermal and structural disorder, and applies it to transition metals and alloys.

Contribution

It develops a novel computational approach combining relativistic band structure and alloy theory to accurately predict Gilbert damping in magnetic materials at finite temperatures.

Findings

Results agree well with experimental data.

Method effectively captures effects of spin-orbit coupling and disorder.

Applicable to a wide range of magnetic alloys and compounds.

Abstract

A method for the calculations of the Gilbert damping parameter $\alpha$ is presented, which based on the linear response formalism, has been implemented within the fully relativistic Korringa-Kohn-Rostoker band structure method in combination with the coherent potential approximation alloy theory. To account for thermal displacements of atoms as a scattering mechanism, an alloy-analogy model is introduced. This allows the determination of $\alpha$ for various types of materials, such as elemental magnetic systems and ordered magnetic compounds at finite temperature, as well as for disordered magnetic alloys at $T = 0$ K and above. The effects of spin-orbit coupling, chemical and temperature induced structural disorder are analyzed. Calculations have been performed for the 3$d$ transition-metals bcc Fe, hcp Co, and fcc Ni, their binary alloys bcc Fe$_{1-x}$Co$_{x}$, fcc Ni$_{1-x}$Fe$_x$, fcc Ni$_{1-x}$Co$_x$ and bcc Fe$_{1-x}$V$_{x}$, and for 5d impurities in transition-metal alloys. All results are in satisfying agreement with experiment.