Visualization of moir\'e magnons in monolayer ferromagnet

TL;DR

This paper demonstrates the visualization and analysis of moiré magnon excitations in monolayer CrBr₃, revealing how moiré patterns influence collective spin excitations in two-dimensional magnetic materials.

Contribution

It introduces the concept of moiré magnons in 2D ferromagnets and provides experimental evidence of their dispersion patterns related to moiré superlattices.

Findings

Moiré magnons emerge from lattice mismatch in monolayer CrBr₃.

Inelastic quasiparticle interference visualizes moiré magnon dispersion.

Moiré patterns enable control over many-body spin excitations.

Abstract

Two-dimensional magnetic materials provide an ideal platform to explore collective many-body excitations associated with spin fluctuations. In particular, it should be feasible to explore, manipulate and ultimately design magnonic excitations in two-dimensional van der Waals magnets in a controllable way. Here we demonstrate the emergence of moir\'e magnon excitations, stemming from the interplay of spin-excitations in monolayer CrBr$_3$ and the moir\'e pattern stemming from the lattice mismatch with the underlying substrate. The existence of moir\'e magnons is further confirmed via inelastic quasiparticle interference, showing the appearance of a dispersion pattern correlated with the moir\'e length scale. Our results provide a direct visualization in real-space of the dispersion of moir\'e magnons, demonstrating the versatility of moir\'e patterns in creating emerging many-body excitations.