New Types of Kitaev Magnets with 3d Metal and Heavy Ligands

Most of recent studies on quantum spin liquids (QSL) has been devoted to the Kitaev model, which is exactly solvable for S=1/2 and where the Kitaev interaction is bond-dependent anisotropic exchange coupling, thus requiring strong spin-orbit coupling (SOC). Such rigorous requirements lead to very limited candidates, i.e., RuCl3 and Na2IrO3, for which the Kitaev interaction results from edge-sharing octahedra and 4d/5d transition metal with strong SOC. In this talk, I will review on recent developments of Kitaev platforms from 4d/5d transition metal compounds to a large series of 3d systems, where the necessary strong SOC are provided by the bridging heavy ligands. Three types of systems, (i) CrI3 and CrSiTe3 type, (ii) NiI2 type and (iii) Na3Co2SbO6 type, each with different spin value, will be introduced. I will mainly focus on their different magnetic interactions from first-principles, but also talk about the attempts to discover possible QSL there.