Magnetism of Kitaev spin-liquid candidate material RuBr$_3$

TL;DR

This study reports the synthesis of RuBr$_{3}$, a new material with a honeycomb lattice similar to $ ext{RuCl}_3$, showing magnetic properties relevant for exploring Kitaev spin liquids and how ligand changes affect interactions.

Contribution

The paper introduces RuBr$_{3}$ as a new analogue to $ ext{RuCl}_3$, demonstrating its potential for studying Kitaev physics through ligand modification.

Findings

RuBr$_{3}$ has a BiI$_3$-type structure with a honeycomb lattice.

RuBr$_{3}$ exhibits zigzag antiferromagnetic order at 34 K.

Ligand substitution influences Kitaev and non-Kitaev interactions.

Abstract

The ruthenium halide $\alpha$-RuCl$_{3}$ is a promising candidate for a Kitaev spin liquid. However, the microscopic model describing $\alpha$-RuCl$_{3}$ is still debated partly because of a lack of analogue materials for $\alpha$-RuCl$_{3}$, which prevents tracking of electronic properties as functions of controlled interaction parameters. Here, we report a successful synthesis of RuBr$_{3}$. The material RuBr$_{3}$~possesses BiI$_3$-type structure (space group: $R\overline{3}$) where Ru$^{3+}$ form an ideal honeycomb lattice. Although RuBr$_{3}$ has a negative Weiss temperature, it undergoes a zigzag antiferromagnetic transition at $T_\mathrm{N}=34$ K, as does $\alpha$-RuCl$_{3}$. Our analyses indicate that the Kitaev and non-Kitaev interactions can be modified in ruthenium trihalides by changing the ligand sites, which provides a new platform for exploring Kitaev spin liquids.