Emergent Chiral Spin State in the Mott Phase of a Bosonic Kane-Mele-Hubbard Model

Recently, the frustrated XY model for spins-1/2 on the honeycomb lattice has attracted a lot of attention in relation with the possibility to realize a chiral spin liquid state. This model is relevant to the physics of some quantum magnets. Using the flexibility of ultra-cold atoms setups, we propose an alternative way to realize this model through the Mott regime of the bosonic Kane-Mele-Hubbard model. The phase diagram of this model is derived using the bosonic dynamical mean-field theory. Focussing on the Mott phase, we investigate its magnetic and topological properties as a function of frustration using exact diagonalization and bosonic dynamical mean-field theory. We do find an emergent chiral spin state in the intermediate frustration regime. This gapped phase displays a chiral order, breaking spontaneously time-reversal and parity symmetry, but its Chern number is zero.