Kitaev material candidates beyond the Iridates

Na2MO3 (M = a tetravalent metal) based Mott insulators have been studied recently as potential candidates to realize Kitaev spin model. 4d5 or 5d5 systems on a Honeycomb lattice exhibit spinorbit assisted Mott insulating ground states. At the strong SOC regime, the ground state for these ions in an octahedral crystal field is dominated by Jeff=1/2 states resulting in bond-dependent anisotropic magnetic exchange in the plane, essential to realize the Kitaev spin model. However, candidates to realize the Kitaev spin model are not limited to 4d/5d systems. Lanthanide elements with significant SOC and inherent anisotropy can also be considered in this context. In this talk, I will present our work on a new lanthanide-based, Kitaev material candidate with a potential Jeff=1/2 ground state. Synthesis and structure of the material will be discussed. Physical property measurements coupled with inelastic neutron scattering results will be utilized to understand the single-ion characteristics of the lanthanide and to unveil the rich low-temperature physics of the material.