Zigzag magnetic order in the Kitaev spin-liquid candidate material <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>RuBr</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> with a honeycomb lattice
Y. Imai, Kazuhiro Nawa, Yasuhiro Shimizu, Wakana Yamada, Hideyuki Fujihara, Takuya Aoyama, Ryotaro Takahashi, Daisuke Okuyama, Takamasa Ohashi, Masato Hagihala, Shuki Torii, Daisuke Morikawa, Masami Terauchi, Takayuki Kawamata, Masatsune Kato, Hirotada Gotou, Masayuki Itoh, T. Sato, Kenya Ohgushi
Abstract
We successfully synthesize ${\mathrm{RuBr}}_{3}$, which is a candidate material of a Kitaev spin liquid, via a high-pressure synthesis. The material ${\mathrm{RuBr}}_{3}$ possesses a ${\mathrm{BiI}}_{3}$-type structure (space group $R\overline{3}$) where ${\mathrm{Ru}}^{3+}$ forms an ideal honeycomb lattice even at room temperature and it does not show a structural transition at low temperatures. ${\mathrm{RuBr}}_{3}$ has a negative Weiss temperature and it undergoes a zigzag antiferromagnetic transition at ${T}_{\mathrm{N}}=34$ K, as does $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ $({T}_{\mathrm{N}}=7--14\phantom{\rule{4pt}{0ex}}\mathrm{K})$ which is a promising candidate for a Kitaev spin liquid. Although both compounds of ${\mathrm{RuBr}}_{3}$ and $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ have a zigzag magnetic order at low temperature, the magnetic order in ${\mathrm{RuBr}}_{3}$ is more robust than in $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$. Our results indicate that the Kitaev and non-Kitaev interactions can be modified in ruthenium trihalides by changing the ligand sites, and will provide another platform for exploring Kitaev spin liquids.