Torsion Effects and LLG Equation

TL;DR

This paper derives a generalized LLG equation incorporating torsion effects from a Dirac equation framework, revealing how torsion influences magnetization dynamics, damping, and precession.

Contribution

It introduces a novel derivation of the LLG equation including torsion effects, linking geometric torsion fields to magnetization behavior.

Findings

Torsion affects damping in magnetization dynamics.

Torsion induces a helix-shaped damping landscape.

Magnetization precession is altered by torsion terms.

Abstract

Based on the non-relativistic regime of the Dirac equation coupled to a torsion pseudo-vector, we study the dynamics of magnetization and how it is affected by the presence of torsion. We consider that torsion interacting terms in Dirac equation appear in two ways one of these is thhrough the covariant derivative considering the spin connection and gauge magnetic field and the other is through a non-minimal spin torsion coupling. We show within this framework, that it is possible to obtain the most general Landau, Lifshitz and Gilbert (LLG) equation including the torsion effects, where we refer to torsion as a geometric field playing an important role in the spin coupling process. We show that the torsion terms can give us two important landscapes in the magnetization dynamics: one of them related with damping and the other related with the screw dislocation that give us a global effect like a helix damping sharped. These terms are responsible for changes in the magnetization precession dynamics.