Phase separation and the existence of superconductivity in a one-dimensional copper-oxygen model

TL;DR

This paper investigates phase separation and superconductivity in a one-dimensional copper-oxygen model, revealing how interactions influence different electronic phases through quantum Monte Carlo simulations.

Contribution

It demonstrates the relationship between phase separation, spin fluctuations, and superconductivity in a CuO chain model, highlighting the effects of doping and repulsion.

Findings

Phase separation occurs with increasing nearest-neighbor repulsion V.

Superconducting fluctuations dominate at higher doping levels.

Spin-density-wave fluctuations precede phase separation.

Abstract

The phase separation instability occurring with increasing nearest-neighbor repulsion V in a two-band Hubbard model (CuO chain) is discussed. Quantum Monte Carlo simulations indicate that this transition is associated with a level-crossing if the filling fraction is close to 1 (half-filled lower band). Spin-density-wave fluctuations then dominate before phase separation. Superconducting fluctuations dominate only at considerably higher doping levels.