We propose a new correlated topological state which we call a higher-order topological Mott insulator (HOTMI). This state exhibits a striking bulk-boundary correspondence due to electron correlations. Namely, the topological properties in the bulk, characterized by the Z3 spin-Berry phase, result in gapless corner modes emerging only in spin excitations (i.e., the single-particle excitations remain gapped around the corner). We demonstrate the emergence of the HOTMI in a Hubbard model on the kagome lattice, and elucidate how strong correlations change gapless corner modes at the noninteracting case.
@article{arxiv.1905.03484,
title = {Higher-order Topological Mott Insulators},
author = {Koji Kudo and Tsuneya Yoshida and Yasuhiro Hatsugai},
journal= {arXiv preprint arXiv:1905.03484},
year = {2019}
}