Achieving unidirectional propagation of twisted magnons in a magnetic nanodisk array

TL;DR

This paper demonstrates theoretically that twisted magnons in a magnetic nanodisk array can propagate unidirectionally by exploiting geometric effects, with potential applications in magnonic communication and computing devices.

Contribution

It introduces a theoretical model explaining multiband twisted magnon propagation and shows how geometric effects induce nonreciprocity enabling unidirectional propagation.

Findings

Multiband structure of twisted magnons in nanodisk arrays

Nonreciprocal dispersion in zigzag structures for specific azimuthal quantum numbers

Unidirectional propagation of twisted magnons with arbitrary nonzero quantum number

Abstract

Twisted magnons (TMs) have great potential applications in communication and computing owing to the orbital angular momentum (OAM) degree of freedom. Realizing the unidirectional propagation of TMs is the key to design functional magnonics devices. Here we theoretically study the propagation of TMs in one-dimensional magnetic nanodisk arrays. By performing micromagnetic simulations, we find that the one-dimensional nanodisk array exhibits a few bands due to the collective excitations of TMs. A simple model by considering the exchange interaction is proposed to explain the emerging multiband structure and theoretical results agree well with micromagnetic simulations. Interestingly, for a zigzag structure, the dispersion curves and propagation images of TMs show obvious nonreciprocity for specific azimuthal quantum number ($l$), which originates from a geometric effect depending on the phase difference of TMs and the relative angle between two adjacent nanodisks. Utilizing this feature, one can conveniently realize the unidirectional propagation of TMs with arbitrary nonzero $l$. Our work provides important theoretical references for controlling the propagation of TMs.