On the metal-insulator transition in the two-chain model of correlated fermions

TL;DR

This paper investigates the doping-induced metal-insulator transition in a two-chain correlated fermion system, revealing universal behavior of superconducting fluctuations and the nature of the transition.

Contribution

It demonstrates that the low-energy properties of the two-chain model are universal across different coupling regimes, with the Luttinger-liquid parameter approaching unity near the transition.

Findings

Luttinger-liquid parameter K_ ho approaches 1 at the transition

Insulating state shows dominant d-type superconducting fluctuations

Universal low-energy behavior across strong and weak coupling limits

Abstract

The doping-induced metal-insulator transition in two-chain systems of correlated fermions is studied using a solvable limit of the t-J model and the fact that various strong- and weak-coupling limits of the two-chain model are in the same phase, i.e. have the same low-energy properties. It is shown that the Luttinger-liquid parameter K_\rho takes the universal value unity as the insulating state (half-filling) is approached, implying dominant d-type superconducting fluctuations, independently of the interaction strength. The crossover to insulating behavior of correlations as the transition is approached is discussed.