Interaction-induced topological transition in spin-orbit coupled ultracold bosons

Recent experiments in ultracold atoms have reported the realization of quantum anomalous Hall phases in spin-orbit coupled systems. Motivated by such advances, we investigate spin-orbit coupled Bose-Bose mixtures in a two-dimensional square optical Raman lattice. Complete phase diagrams are obtained via a nonperturbative real-space bosonic dynamical mean-field theory. Various quantum phases are predicted, including Mott phases with z -ferromagnetic, xy -antiferromagnetic and vortex textures, and superfluid phases with the exotic spin orders, induced by the competition between the lattice hopping and spin-orbit coupling. To explain the underlying physics in the Mott regime, an effective Hamiltonian is derived based on second-order perturbation theory, where pseudospin order stems from the interplay of effective Dzyaloshinskii-Moriya superexchange and Heisenberg interactions. In the presence of the Zeeman field, the competition of strong interaction and Zeeman energy facilitates a topological phase, which is confirmed both by the nontrivial topological Bott index and spectral function with topological edge states. Our work indicates that spin-orbit coupling can induce rich non-Abelian topological physics in strongly correlated ultracold atomic systems.