# Chiral anomaly of Weyl magnons in stacked honeycomb ferromagnets

## TL;DR

This paper demonstrates the realization of Weyl magnons in stacked honeycomb ferromagnets and explores their chiral anomaly, showing how magnetic and electric field gradients induce unidirectional magnon currents with potential spin and heat transport applications.

## Contribution

It introduces a new platform for Weyl magnons in stacked honeycomb ferromagnets and reveals their chiral anomaly driven by magnetic and electric field gradients.

## Key findings

- Weyl magnons can be realized in stacked honeycomb ferromagnets.
- Magnonic Landau levels are quantized via the Aharonov-Casher effect.
- Magnon currents depend linearly on field gradients.

## Abstract

Chiral anomaly of Weyl magnons (WMs), featured by nontrivial band crossings at paired Weyl nodes (WNs) of opposite chirality, is investigated. It is shown that WMs can be realized in stacked honeycomb ferromagnets. Using the Aharonov-Casher effect that is about the interaction between magnetic moments and electric fields, the magnon motion in honeycomb layers can be quantized into magnonic Landau levels (MLLs). The zeroth MLL is chiral so that unidirectional WMs propagate in the perpendicular (to the layer) direction for a given WN under a magnetic field gradient from one WN to the other and change their chiralities, resulting in the magnonic chiral anomaly (MCA). A net magnon current carrying spin and heat through the zeroth MLL depends linearly on the magnetic field gradient and the electric field gradient in the ballistic transport.