Interband excitations in the 1D limit of two-band fractional Chern insulators

TL;DR

This paper examines the stability of one-dimensional fractional Chern insulators at filling factor 1/3, analyzing interband interactions, excitations, and the effects of deviations from ideal conditions, using numerical methods.

Contribution

It introduces a construction for excitations in the infinite-interaction limit and demonstrates the robustness of the energy gap in the thermodynamic limit.

Findings

The energy gap remains finite in the thermodynamic limit.

Deviations from ideal dimerization reduce the stability of FCI-like states.

The dimer structure approach applies to other models like the checkerboard lattice.

Abstract

We investigate the stability of the one-dimensional limit of $\nu=1/3$ Laughlin-like fractional Chern insulator with respect to the interband interaction. We propose a construction for the excitations in the infinite-interaction case and show that the energy gap remains finite in the thermodynamic limit. Next, by means of exact diagonalization and Density Matrix Renormalization Group approaches, we consider deviations from ideal dimerization and show that they reduce the stability of the FCI-like states. Finally, to show that our approach is not restricted to one model, we identify the dimer structure behind the thin-torus limit of other system -- the checkerboard lattice.