Topological Mott Insulator with Bosonic Edge Modes in 1D Fermionic Superlattices

TL;DR

This paper discovers a new topological Mott insulator in 1D fermionic superlattices, characterized by bosonic edge modes and driven by interactions, with potential for experimental realization.

Contribution

It identifies a novel topological Mott insulator state with bosonic edge modes in 1D fermionic superlattices using DMRG, highlighting a transition from fermionic to bosonic edge excitations.

Findings

Edge excitations change from fermionic to bosonic modes across the transition.

The topological Mott state is characterized by a spin Chern number.

Experimental setup proposed for observing the topological Mott state.

Abstract

We investigate topological phase transitions driven by interaction and identify a novel topological Mott insulator state in one-dimensional fermionic optical superlattices through numerical density matrix renormalization group (DMRG) method. Remarkably, the low-energy edge excitations change from spin-1/2 fermionic single-particle modes to spin-1 bosonic collective modes across the phase transition. Due to spin-charge separation, the low-energy theory is governed by an effective spin superexchange model, whereas the charge degree of freedom is fully gapped out. Such topological Mott state can be characterized by a spin Chern number and gapless magnon modes protected by a finite spin gap. The proposed experimental setup is simple and may pave the way for the experimental observation of exotic topological Mott states.