Tailoring High-Frequency Magnonics in Monolayer Chromium Trihalides

TL;DR

This paper investigates the tunable spin wave properties of monolayer chromium trihalides, demonstrating their potential for high-frequency magnonic applications through strain, defect engineering, and moiré patterning.

Contribution

It provides a comprehensive analysis of spin wave control in 2D chromium trihalides, highlighting new methods for tuning and guiding magnons in these materials.

Findings

Spin wave dispersion can be tuned by strain over a broad frequency range.

Halide vacancies induce Dzyaloshinskii Moriya interactions that scatter spin waves.

Moiré patterns enable the creation of magnonic crystals in the terahertz range.

Abstract

Monolayer chromium trihalides, the archetypal two dimensional (2D) magnetic materials, are readily suggested as a promising platform for high frequency magnonics. Here we detail the spin wave properties of monolayer CrBr$_3$ and CrI$_3$, using spin dynamics simulations parametrized from the first principles. We reveal that spin wave dispersion can be tuned in a broad range of frequencies by strain, paving the way towards flexo magnonic applications. We further show that ever present halide vacancies in these monolayers host sufficiently strong Dzyaloshinskii Moriya interaction to scatter spin waves, which promotes design of spin-wave guides by defect engineering. Finally we discuss the spectra of spin-waves propagating across a moir\'e periodic modulation of magnetic parameters in a van der Waals heterobilayer, and show that the nanoscale moir\'e periodicities in such samples are ideal for realization of a magnonic crystal in the terahertz frequency range. Recalling the additional tunability of magnetic 2D materials by electronic gating, our results situate these systems among the front-runners for prospective high frequency magnonic applications.