Chiral asymmetry of the spin-wave spectra in ultrathin magnetic films

TL;DR

This paper investigates how Dzyaloshinskii-Moriya interactions induce chiral asymmetry in the spin-wave spectra of ultrathin magnetic films, combining symmetry analysis, first-principles calculations, and simplified modeling.

Contribution

It demonstrates the presence of chiral asymmetry in spin-wave spectra due to Dzyaloshinskii-Moriya interactions in ultrathin films through theoretical and computational methods.

Findings

Asymmetry of spin-wave spectra in Fe monolayer on W(110)

Quantitative interpretation using Dzyaloshinskii-Moriya vectors

Theoretical prediction to guide experimental detection

Abstract

We raise the possibility that the chiral degeneracy of the magnons in ultrathin films can be lifted due to the presence of Dzyaloshinskii-Moriya interactions. By using simple symmetry arguments, we discuss under which conditions such a chiral asymmetry occurs. We then perform relativistic first principles calculations for an Fe monolayer on W(110) and explicitly reveal the asymmetry of the spin-wave spectrum in case of wave-vectors parallel to the (001) direction. Furthermore, we quantitatively interpret our results in terms of a simplified spin-model by using calculated Dzyaloshinskii-Moriya vectors. Our theoretical prediction should inspire experiments to explore the asymmetry of spin-waves, with a particular emphasis on the possibility to measure the Dzyaloshinskii-Moriya interactions in ultrathin films.