Neutron Scattering Study of Honeycomb Lithium Iridate Kitaev-Spin Liquid Candidate

The realization of materials that exhibit a quantum spin liquid state beyond one dimension has been a central focus of condensed matter physics research in recent years. The only exactly theoretically solvable model of a spin-liquid is the Kitaev model, which consists of a 2D honeycomb lattice of J_eff = ½ moment magnetic ions. Here we examine a candidate for the realization of this state. The structure consists of a honeycomb lattice of Ir4+ ions with strong spin-orbit coupling to support the bond dependent exchange interactions required in the Kitaev model. Hydrogen present reduces any interlayer non-Kitaev interactions which causes order in similar Lithium Iridates. Using inelastic neutron scattering on the SEQUOIA instrument at ORNL, we probed the material for magnetic excitations. NMR studies show no magnetic ordering, ferromagnetic interactions are observed in Curie-Weiss fitting, and the inelastic neutron scattering roughly shows broad low-Q excitations predicted by the Kitaev model. Together these traits encourage the possibility of this material exhibiting a spin-liquid state.