A model for the phase separation controlled by doping and the internal chemical pressure in different cuprate superconductors

TL;DR

This paper presents a two-band model to understand phase separation in cuprate superconductors, linking doping, chemical pressure, and charge carrier localization, successfully reproducing experimental phase diagrams.

Contribution

It introduces a novel two-band theoretical framework that connects internal chemical pressure and doping to phase separation in cuprates, aligning with experimental observations.

Findings

Reproduces phase separation regime at doping > 1/8

Links internal chemical pressure to energy splitting in bands

Matches experimental phase diagrams of cuprates

Abstract

In the framework of a two-band model, we study the phase separation regime of different kinds of strongly correlated charge carriers as a function of the energy splitting between the two sets of bands. The narrow (wide) band simulates the more localized (more delocalized) type of charge carriers. By assuming that the internal chemical pressure on the CuO$_2$ layer due to interlayer mismatch controls the energy splitting between the two sets of states, the theoretical predictions are able to reproduce the regime of phase separation at doping higher than 1/8 in the experimental pressure-doping-$T_c$ phase diagram of cuprates at large microstrain as it appears in overoxygenated La$_2$CuO$_4$.