Topological Order and Semions in a Strongly Correlated Quantum Spin Hall Insulator

Understand

We provide a self-consistent mean-field framework to study the effect of strong interactions in a quantum spin Hall insulator on the honeycomb lattice.

• We identify an exotic phase for large spin-orbit coupling and intermediate Hubbard interaction.
• This phase is gapped in the bulk, has gapless edge states and does not break any symmetry.
• Instead, we find a four-fold topological degeneracy of the ground state on the torus and fractionalized excitations with semionic mutual braiding statistics.