Higher-Order Topological Mott Insulator on the Pyrochlore Lattice

Abstract

We find a third-order topological Mott insulator in the Hubbard model on the pyrochlore lattice by numerically-exact quantum Monte Carlo simulations. This phase is adiabatically connected to a third-order topological insulator in the noninteracting limit, which features gapless modes around the corners of the pyrochlore lattice and is characterized by a Z4 spin-Berry phase. The difference between the correlated and non-correlated topological phases is that in the former phase the gapless corner modes emerge only in spin excitations being Mott-like. We also show that the topological phase transition from the third-order topological Mott insulator to the usual Mott insulator occurs when the bulk spin gap solely closes.

Higher-order topological quantum paramagnets

“…Within this class, the recently discovered higher-order topological insulators (HOTIs) [21,22] present unusual properties that generalize the standard bulk-boundary correspondence [23]: they support gapless states in boundaries of co-dimension larger that one, such as corner or hinge states [24,25]. Although non-interacting HOTIs have been extensively investigated, and in several cases realized experimentally [26][27][28][29][30][31][32][33], interacting higher-order symmetry-protected topological (HOSPT) phases are only starting to be explored [34][35][36][37][38][39][40][41][42].…”