Torsion induced effects in magnetic nanowires

TL;DR

This paper investigates how torsion affects magnetic properties and spin-wave dynamics in helix-shaped nanowires, revealing new equilibrium states and symmetry-breaking effects confirmed by simulations.

Contribution

It provides a theoretical analysis of torsion-induced effects on magnetization states and spin-wave behavior in magnetic helix wires, including the influence of curvature and torsion.

Findings

Identification of two equilibrium magnetization states depending on curvature and torsion.

Torsion acts as an effective magnetic field influencing spin-wave dynamics.

Discovery of mirror symmetry breaking in the spin-wave spectrum due to curvature-induced interactions.

Abstract

Magnetic helix wire is one of the most simple magnetic systems which manifest properties of both curvature and torsion. There exist two equilibrium states in the helix wire with easy-tangential anisotropy: a quasi-tangential magnetization distribution in case of relatively small curvatures and torsions, and an onion state in opposite case. In the last case the magnetization is close to tangential one, deviations are caused by the torsion and curvature. Possible equilibrium magnetization states in the helix magnet with different anisotropy directions are studied theoretically. The torsion also essentially influences the spin-wave dynamics, acting as an effective magnetic field. Originated from the curvature induced effective Dzyaloshinskii interaction, this magnetic field leads to the coupling between the helix chirality and the magnetochirality, it breaks mirror symmetry in spin-wave spectrum. All analytical predictions on magnetization statics an dynamics are well confirmed by the direct spin lattice simulations.