Charge and spin gaps of the ionic Hubbard model with density-dependent hopping

TL;DR

This study investigates the charge and spin gaps in the ionic Hubbard model with density-dependent hopping, identifying quantum critical points and the fully gapped dimerized insulator phase, and explores adiabatic charge pumping within this framework.

Contribution

It introduces the analysis of charge and spin gaps in the ionic Hubbard model with density-dependent hopping, highlighting the existence of quantum critical points and the dimerized insulator phase.

Findings

Identification of quantum critical points in charge and spin sectors.

Existence of a fully gapped spontaneously dimerized insulator phase.

Feasibility of adiabatic charge pumping limited by gap sizes.

Abstract

We calculate the charge gap $\Delta E_C$ and the spin gap $\Delta E_S$ of the ionic Hubbard chain including electron-hole symmetric density-dependent hopping. The vanishing of $\Delta E_C$ ($\Delta E_S$) signals a quantum critical point (QCP) in the charge (spin) sector. Between both critical points, the system is a fully gapped spontaneously dimerized insulator (SDI). We focus our study in this region. Including alternation in the hopping, it is possible to perform an adiabatic Thouless pump of one charge per cycle, but with a velocity limited by the size of the gaps.