# Honeycomb rare-earth magnets with anisotropic exchange interactions

### Submission summary

 As Contributors: Gang Chen · Zhu-Xi Luo Preprint link: scipost_202003_00001v6 Date accepted: 2020-07-24 Date submitted: 2020-05-14 02:00 Submitted by: Luo, Zhu-Xi Submitted to: SciPost Physics Academic field: Physics Specialties: Condensed Matter Physics - Theory Approach: Theoretical

### 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.

Published as SciPost Phys. Core 3, 004 (2020)

In this new version, we mainly expand the discussions for the setup of the Hamiltonian, the magnetometry and the electron spin resonance results. Other revisions involve explanations of notations and corrections of typos.

### List of changes

1. Added two sentences below equations (1) and (3) to further explain the setup.
3. Added another expression for $\Gamma_{ij,zz}$ to equation (12).
4. In the caption of figure 3 and below Eqn (17), added more explanations about the ESR results.
5. Added a reference [45] above Eqn (13) and rephrased the sentences.
6. Added a remark at the beginning of section V about the scale of exchange.
7. Added an estimation of the YbCl3 exchange scales in the second paragraph of the discussion section.

Smaller edits:
9. The second paragraph in the introduction section, changed "proximity" to "relevance".
10. At the beginning of section III, specified that Appendix B contains more details.
11. Below equations (5) and (7), added more explanations of notations.
12. The last paragraph of the last column on page 3, corrected a typo "there is"->"this is".
13. In the caption of figure 2, added more explanations of notations.
14. Below Eqn (11), corrected a typo "a traceless"->"is a traceless".
15. Changed "in" to "along" in the title of section V. B.
16. Corrected a typo "spin-obital" -> "spin-orbital" in the second paragraph of left column on page 7.
17. Added explanation of notation below equation (A1) and (B5).

### Submission & Refereeing History

#### Published as SciPost Phys. Core 3, 004 (2020)

Resubmission scipost_202003_00001v6 on 14 May 2020
Submission scipost_202003_00001v1 on 4 March 2020

## Reports on this Submission

### Report

The authors have properly addressed all my comments and clarified all my questions. Likewise, great attention has been given by the authors to the reports of other referees, with detailed responses. As a result, the authors have produces a more clear and improved version of their manuscript, which I can recommend publication in this Journal.

• validity: -
• significance: -
• originality: -
• clarity: -
• formatting: -
• grammar: -

### Report

The authors have properly taken care of my questions and suggestions. I think that the paper can now be published.

• validity: top
• significance: good
• originality: high
• clarity: high
• formatting: excellent
• grammar: good