Topological charge excitations and Green's function zeros in paramagnetic Mott insulators
Phys. Rev. B 112, 085105 – Published 5 August, 2025
DOI: https://doi.org/10.1103/4k4y-4hj4
Abstract
We investigate the emergence of topological features in the charge excitations of Mott insulators in the Chern-Hubbard model. In the strong correlation regime, treating electrons as the sum of holons and doublons excitation, we compute the topological phase diagram of Mott insulators at half-filling using composite operator formalism. The Green's function zeros manifest as tightly bound pairs of such elementary excitations of Mott insulators. Our analysis examines the winding number associated with the occupied Hubbard bands and the band of Green's function zeros. We show that both the poles and zeros exhibit gapless states and zeros, respectively, in line with bulk-boundary correspondence. The gapless edge states emerge in a junction geometry connecting a topological Mott band insulator and a topological Mott zeros phase. These include an edge electronic state that carries a charge and a charge-neutral gapless zero mode. Our study is relevant to several twisted materials with flat bands where interactions play a dominant role.
