Hydrated lithium intercalation into the Kitaev spin liquid candidate material α−RuCl3

We study the transport and magnetic properties of hydrated and lithium-intercalated $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}₃,{\mathrm{Li}}_x{\mathrm{RuCl}}₃\ifmmode\cdot\else\textperiodcentered\fi{}y{\mathrm{H}}₂\mathrm{O}$, to investigate the effect on mobile-carrier doping into candidate materials for a realization of a Kitaev model. From thermogravimetric and one-dimensional electron map analyses, we find two crystal structures of this system, that is, monolayer hydrated ${\mathrm{Li}}_x{\mathrm{RuCl}}₃\ifmmode\cdot\else\textperiodcentered\fi{}y{\mathrm{H}}₂\mathrm{O}\phantom{\rule{4pt}{0ex}}(x\ensuremath{\approx}0.56,y\ensuremath{\approx}1.3)$ and bilayer hydrated ${\mathrm{Li}}_x{\mathrm{RuCl}}₃\ifmmode\cdot\else\textperiodcentered\fi{}y{\mathrm{H}}₂\mathrm{O}\phantom{\rule{4pt}{0ex}}(x\ensuremath{\approx}0.56,y\ensuremath{\approx}3.9)$. The temperature dependence of the electrical resistivity shows a temperature hysteresis at 200--270 K, which is considered to relate to the formation of a charge order. The antiferromagnetic order at 7--13 K in pristine $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}₃$ is successfully suppressed down to 2 K in bilayer hydrated ${\mathrm{Li}}_x{\mathrm{RuCl}}₃\ifmmode\cdot\else\textperiodcentered\fi{}y{\mathrm{H}}₂\mathrm{O}$, which is sensitive to not only the electronic state of Ru but also the interlayer distance between Ru-Cl planes.