Inhomogeneously doped two-leg ladder systems

TL;DR

This paper investigates how a chemical potential difference between the legs of a two-leg ladder affects superconductivity, showing that it destabilizes Cooper pairing and leads to a breakdown of superconductivity through various analytical and numerical methods.

Contribution

It provides a comprehensive analysis of the destabilizing effect of chemical potential differences on superconductivity in two-leg ladder systems using multiple theoretical and numerical approaches.

Findings

Chemical potential difference harms Cooper pairing.

Superconductivity becomes unstable beyond a critical chemical potential difference.

Doping-dependent phase diagram shows breakdown of superconductivity.

Abstract

A chemical potential difference between the legs of a two-leg ladder is found to be harmful for Cooper pairing. The instability of superconductivity in such systems is analyzed by compairing results of various analytical and numerical methods. Within a strong coupling approach for the t-J model, supplemented by exact numerical diagonalization, hole binding is found unstable beyond a finite, critical chemical potential difference. The spinon-holon mean field theory for the t-J model shows a clear reduction of the the BCS gaps upon increasing the chemical potential difference leading to a breakdown of superconductivity. Based on a renormalization group approach and Abelian bosonization, the doping dependent phase diagram for the weakly interacting Hubbard model with different chemical potentials was determined.