Spontaneous fractional Chern insulators in transition metal dichalcogenide moiré superlattices

The Moiré superlattice realized in two-dimensional heterostructures offers an exciting platform to access

strongly correlated electronic states. In this work, we study transition metal dichalcogenides (TMD) Moiré

superlattices with time-reversal symmetry and nontrivial spin/valley-Chern numbers. Utilizing realistic material

parameters and the method of exact diagonalization, we find that at a certain twisting angle and fractional

filling, gapped fractional topological states, i.e., fractional Chern insulators, are naturally stabilized by simply

introducing the Coulomb repulsion. In contrast to fractional quantum Hall systems, where the time-reversal

symmetry has to be broken explicitly, these fractional states break the time-reversal symmetry spontaneously.

We show that the Chern number contrasting in the opposite valleys imposes a strong constraint on the nature of

fractional Chern insulator and the associated low-energy excitations.