Ab initio study of the influence of nanoscale doping inhomogeneities in the phase separated state of La$_{1-x}$Ca$_{x}$MnO$_3$

TL;DR

This study uses ab initio calculations to explore how nanoscale doping inhomogeneities influence phase separation in La$_{1-x}$Ca$_{x}$MnO$_3$, revealing that dopant distribution drives magnetic and electronic heterogeneity.

Contribution

It demonstrates that non-isotropic dopant distribution is energetically favored, leading to nanometric phase separation correlated with magnetic order in manganites.

Findings

Dopant inhomogeneity induces magnetic phase separation.

Hole-rich regions are more ferromagnetic.

Hole-poor regions tend to be antiferromagnetic.

Abstract

The chemical influence in the phase separation phenomenon that occurs in perovskite manganites is discussed by means of ab initio calculations. Supercells have been used to simulate a phase separated state, that occurs at Ca concentrations close to the localized to itinerant crossover. We have first considered a model with two types of magnetic ordering coexisting within the same compound. This is not stable. However, a non-isotropic distribution of chemical dopants is found to be the ground state. This leads to regions in the system with different effective concentrations, that would always accompany the magnetic phase separation at the same nanometric scale, with hole-rich regions being more ferromagnetic in character and hole-poor regions being in the antiferromagnetic region of the phase diagram, as long as the system is close to a phase crossover.