Atomistic spin dynamic method with both damping and moment of inertia effects included from first principles

TL;DR

This paper develops a first-principles atomistic spin dynamic method that incorporates damping and moment of inertia effects, enabling femtosecond regime simulations of magnetization dynamics.

Contribution

It introduces a generalized equation of motion for magnetization dynamics including inertia, derived from first principles, extending the traditional Landau-Lifshitz-Gilbert framework.

Findings

Derived a non-local generalized equation of motion for spin dynamics.

Showed how exchange interaction, damping, and inertia can be computed from first principles.

Demonstrated the feasibility of femtosecond regime simulations with the new model.

Abstract

We consider spin dynamics for implementation in an atomistic framework and we address the feasibility of capturing processes in the femtosecond regime by inclusion of moment of inertia. In the spirit of an {\it s-d} -like interaction between the magnetization and electron spin, we derive a generalized equation of motion for the magnetization dynamics in the semi-classical limit, which is non-local in both space and time. Using this result we retain a generalized Landau-Lifshitz-Gilbert equation, also including the moment of inertia, and demonstrate how the exchange interaction, damping, and moment of inertia, all can be calculated from first principles.