Coulomb Interactions and Nanoscale Electronic Inhomogeneities in Manganites

TL;DR

This study uses simulations of Coulomb interactions among electronic fluids and dopants in manganites to explain intrinsic nanoscale inhomogeneities, challenging previous phase competition theories.

Contribution

It introduces a new model incorporating Coulomb interactions that accounts for nanoscale inhomogeneities without relying on phase competition or disorder.

Findings

Nanoscale inhomogeneities arise from Coulomb frustration of phase separation.

The model reproduces experimental colossal responses.

Homogeneity appears at meso-scales despite nano-scale inhomogeneity.

Abstract

We address the issue of endemic electronic inhomogeneities in manganites using extensive simulations on a new model with Coulomb interactions amongst two electronic fluids, one localized (polaronic), the other extended (band-like), and dopant ions. The long range Coulomb interactions frustrate phase separation induced by the strong on site repulsion between the fluids. A single quantum phase ensues which is intrinsically and strongly inhomogeneous at a nano-scale, but homogeneous on meso-scales, with many characteristics (including colossal responses)that agree with experiments. This, we argue, is the origin of nanoscale inhomogeneities in manganites, rather than phase competition and disorder related effects as often proposed.