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arXiv · 2302.00540

Sweet spot in the RuCl$_3$ magnetic system: nearly ideal $j_{\mathrm{eff}}\!=\!1/2$ moments and maximized $K/J$ ratio under pressure

Pritam Bhattacharyya·Liviu Hozoi·Quirin Stahl·Jochen Geck·Nikolay A. Bogdanov
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Abstract

Maximizing the ratio between Kitaev and residual Heisenberg interactions is a major goal in nowadays research on Kitaev-Heisenberg quantum magnets. Here we investigate Kitaev-Heisenberg exchange in a recently discovered crystalline phase of RuCl$_3$ under presure -- it displays unusually high symmetry, with only one type of Ru-Ru links, and uniform Ru-Cl-Ru bond angles of $\approx$93$^{\circ}$. By quantum chemical calculations in this particular honeycomb-lattice setting we find a very small $J$, which yields a $K/J$ ratio as large as $\sim$100. Interestingly, we also find that this is associated with vanishingly small $d$-shell trigonal splittings, i.\,e., minimal departure from ideal $j_{\mathrm{eff}}\!=\!1/2$ moments. This reconfirms RuCl$_3$ as a most promising platform for materializing the much sought-after Kitaev spin-liquid phase and stimulates further experiments under strain and pressure.

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Pritam Bhattacharyya, Liviu Hozoi, Quirin Stahl, Jochen Geck, Nikolay A. Bogdanov. 2023-02-01. Sweet spot in the RuCl$_3$ magnetic system: nearly ideal $j_{\mathrm{eff}}\!=\!1/2$ moments and maximized $K/J$ ratio under pressure. https://doi.org/10.1103/physrevb.108.l161107

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