Spinful fermionic ladders at incommensurate filling: Phase diagram, local perturbations, and ionic potentials

TL;DR

This paper investigates how external potentials influence transport and phase transitions in a two-leg fermionic ladder model at incommensurate filling, revealing phase categorization, hopping-driven transitions, and effects of ionic potentials.

Contribution

It introduces a comprehensive phase diagram for the model, classifies all phases and transitions, and describes the impact of ionic potentials on bulk properties and long-range order.

Findings

Identification of all phases and transitions at incommensurate filling

Introduction of hopping-driven transitions as inter-chain hopping varies

Demonstration of ionic potentials inducing long-range order

Abstract

We study the effect of external potential on transport properties of the fermionic two-leg ladder model. The response of the system to a local perturbation is strongly dependent on the ground state properties of the system and especially on the dominant correlations. We categorise all phases and transitions in the model (for incommensurate filling) and introduce "hopping-driven transitions" that the system undergoes as the inter-chain hopping is increased from zero. We also describe the response of the system to an ionic potential. The physics of this effect is similar to that of the single impurity, except that the ionic potential can affect the bulk properties of the system and in particular induce true long range order.