Coupled spin- 12 antiferromagnetic chain Cs2LiRuCl6 with partially disordered crystal lattice

We determined the crystal structure of ${\mathrm{Cs}}_{2}{\mathrm{LiRuCl}}_{6}$, which was synthesized in this work, and investigated its magnetic properties. ${\mathrm{Cs}}_{2}{\mathrm{LiRuCl}}_{6}$ has a hexagonal structure composed of linear chains of face-sharing ${\mathrm{RuCl}}_{6}$ and ${\mathrm{LiCl}}_{6}$ octahedra. In two thirds of the structural chains, ${\mathrm{Ru}}^{3+}$ and ${\mathrm{Li}}^{+}$ sites are almost ordered, while in the other chains their sites are disordered. This situation is analogous to the ground state of the antiferromagnetic Ising model on a triangular lattice. Using electron paramagnetic resonance, we evaluated the $g$ factors of ${\mathrm{Ru}}^{3+}$ with effective spin-$\frac{1}{2}$ as ${g}_{c}\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}2.72$ and ${g}_{ab}\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}1.50$ for magnetic fields $H$ parallel and perpendicular to the $c$ axis, respectively. Magnetization curves for $H\ensuremath{\parallel}c$ and $H\phantom{\rule{0.16em}{0ex}}\ensuremath{\perp}\phantom{\rule{0.16em}{0ex}}c$ are highly anisotropic. However, these magnetization curves approximately coincide when normalized by the $g$ factors. It was found from the magnetization and specific heat results that ${\mathrm{Cs}}_{2}{\mathrm{LiRuCl}}_{6}$ can be described as a coupled one-dimensional $S\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}1/2$ Heisenberg-like antiferromagnet with $J/{k}_{\mathrm{B}}\phantom{\rule{0.16em}{0ex}}\ensuremath{\simeq}\phantom{\rule{0.16em}{0ex}}3.7$ K. Three-dimensional ordering occurs at ${T}_{\mathrm{N}}\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}0.48$ K. A magnetic phase diagram for $H\ensuremath{\parallel}c$ is also presented.