Li2RhO3: A spin-glassy relativistic Mott insulator

Motivated by the rich interplay among electronic correlation, spin-orbit coupling (SOC), crystal-field splitting, and geometric frustrations in the honeycomblike lattice, we systematically investigated the electronic and magnetic properties of Li2RhO3. The material is semiconducting with a narrow band gap of Delta similar to 78 meV, and its temperature dependence of resistivity conforms to a three-dimensional variable range hopping mechanism. No long-range magnetic ordering was found down to 0.5 K, due to the geometric frustrations. Instead, single atomic spin-glass behavior below the spin-freezing temperature (similar to 6 K) was observed and its spin dynamics obeys the universal critical slowing down scaling law. A first-principles calculation suggested it to be a relativistic Mott insulator mediated by both electronic correlation and SOC. With moderate strength of electronic correlation and SOC, our results shed light on the research of the Heisenberg-Kitaev model in realistic materials.