Topological order in a correlated three-dimensional topological insulator.
Motivated by experimental progress in the growth of heavy transition metal oxides, we theoretically study a class of lattice models of interacting fermions with strong spin-orbit coupling. Focusing on interactions of intermediate strength, we derive a low-energy effective field theory for a fully gapped, topologically ordered, fractionalized state with an eightfold ground-state degeneracy. This state is a fermionic symmetry-enriched topological phase with particle-number conservation and time-reversal symmetry. The topological terms in the effective field theory describe a quantized magnetoelectric response and nontrivial mutual braiding statistics of dynamical extended vortex loops with emergent fermions in the bulk. We explicitly compute the expected mutual statistics in a specific model on the pyrochlore lattice within a slave-particle mean-field theory. We argue that our model also provides a possible condensed-matter realization of oblique confinement.
Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544, USA.
Joseph
J
Maciejko
Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
Victor
V
Chua
Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
Gregory A
GA
Fiete