Fermionic Symmetry Protected Topological Phase Induced by Interactions

TL;DR

This paper demonstrates that strong interactions can induce new fermionic symmetry protected topological phases absent in free fermion systems, using a three-leg ladder model analyzed via density-matrix renormalization group.

Contribution

It provides a systematic study of interaction-induced topological phases in a fermionic ladder model, revealing a nontrivial SPT phase arising solely from interactions.

Findings

Identification of a trivial phase connected to band insulators

Discovery of a nontrivial interaction-induced SPT phase

Use of DMRG to analyze topological properties in fermionic systems

Abstract

Strong interactions can give rise to new fermionic symmetry protected topological phases which have no analogs in free fermion systems. As an example, we have systematically studied a spinless fermion model with $U(1)$ charge conservation and time reversal symmetry on a three-leg ladder using density-matrix renormalization group. In the non-interacting limit, there are no topological phases. Turning on interactions, we found two gapped phases. One is trivial and is adiabatically connected to a band insulator, while another one is a nontrivial symmetry protected topological phase resulting from strong interactions.