Nonreciprocal inertial spin-wave dynamics in twisted magnetic nanostrips

TL;DR

This paper presents a theoretical study of inertial spin-wave dynamics in twisted magnetic nanostrips, revealing nonreciprocal THz oscillations influenced by geometry, topology, and inertia, with potential applications in magnonics and spintronics.

Contribution

It introduces a new theoretical framework linking curvature, torsion, and inertia to nonreciprocal spin-wave behavior in twisted magnetic nanostrips, highlighting topological effects.

Findings

Nonreciprocal THz spin-wave spectra due to geometric chirality.

Analytical expressions for dispersion and linewidths in different regimes.

Topological geometries affect wavenumber quantization and spin-wave transport.

Abstract

We develop a theoretical framework for inertial spin-wave dynamics in three-dimensional twisted soft-magnetic nanostrips, where curvature and torsion couple with magnetic inertia to generate terahertz (THz) magnetic oscillations. The resulting spin-wave spectra exhibit pronounced nonreciprocity due to effective symmetry breaking arising from geometric chirality and inertial effects. We show that this behavior is governed by a curvature-induced geometric (Berry) phase, which we analytically capture through compact expressions for dispersion relations and spectral linewidths in both nutational (THz) and precessional (GHz) regimes. Topological variations, including M\"obius and helical geometries, impose distinct wavenumber quantization rules, elucidating the role of topology in spin-wave transport. These results position twisted magnetic strips as a viable platform for curvilinear THz magnonics and nonreciprocal spintronic applications.