Kitaev materials In transition-metal compounds with partially filled 4d and 5d shells spin–orbit entanglement, electronic correlations, and crystal-field effects conspire to give rise to a variety of novel forms of topological quantum matter. This includes Kitaev materials — a family of spin–orbit assisted Mott insulators, in which local, spin–orbit entangled j=1/2 moments form that are subject to dominant bond-directional Ising exchange interactions. On a conceptual level, Kitaev materials att...