Electronic Structures of Kitaev Magnet Candidates RuCl[sub.3] and RuI[sub.3]

Layered honeycomb magnets with strong atomic spin–orbit coupling at transition metal sites have been intensively studied for the search of Kitaev magnetism and the resulting non-Abelian braiding statistics. α-RuCl[sub.3] has been the most promising candidate, and there have been several reports on the realization of sibling compounds α-RuBr[sub.3] and α-RuI[sub.3] with the same crystal structure. Here, we investigate correlated electronic structures of α-RuCl[sub.3] and α-RuI[sub.3] by employing first-principles dynamical mean-field theory. Our result provides a valuable insight into the discrepancy between experimental and theoretical reports on transport properties of α-RuI[sub.3] , and suggests a potential realization of correlated flat bands with strong spin–orbit coupling and a quantum spin-Hall insulating phase in α-RuI[sub.3] .