# Honeycomb rare-earth magnets with anisotropic exchange interactions

## TL;DR

This paper investigates honeycomb lattice rare-earth magnets with anisotropic exchange interactions, analyzing their thermodynamic properties, ESR linewidths, and potential topological magnons under strong magnetic fields, relevant for Kitaev materials.

## Contribution

It provides a comprehensive theoretical analysis of anisotropic spin interactions in rare-earth honeycomb magnets, including high-temperature series expansion and spin-wave studies under strong fields.

## Key findings

- Heat capacity and susceptibilities characterized.
- ESR linewidth as a signature of anisotropic interactions.
- Potential for topological magnons under strong magnetic fields.

## Abstract

We study the rare-earth magnets on a honeycomb lattice, and are particularly interested in the experimental consequences of the highly anisotropic spin interaction due to the spin-orbit entanglement. We perform a high-temperature series expansion using a generic nearest-neighbor Hamiltonian with anisotropic interactions, and obtain the heat capacity, the parallel and perpendicular spin susceptibilities, and the magnetic torque coefficients. We further examine the electron spin resonance linewidth as an important signature of the anisotropic spin interactions. Due to the small interaction energy scale of the rare-earth moments, it is experimentally feasible to realize the strong-field regime. Therefore, we perform the spin-wave analysis and study the possibility of topological magnons when a strong field is applied to the system. The application and relevance to the rare-earth Kitaev materials are discussed.