Nanoscale Phase Coexistence and Percolative Quantum Transport

TL;DR

This paper investigates nanoscale phase coexistence in magnetic materials, using a novel Monte Carlo approach to analyze cluster distribution, electronic properties, and resistivity, providing microscopic insights into percolative quantum transport.

Contribution

It introduces a new Monte Carlo technique for large-scale simulation of phase coexistence, enabling detailed study of cluster distribution and resistivity in magnetic materials.

Findings

Recovered cluster coexistence consistent with previous small-system results

Analyzed cluster distribution across various parameters

Provided microscopic estimates of resistivity matching percolation scenarios

Abstract

We study the nanoscale phase coexistence of ferromagnetic metallic (FMM) and antiferromagnetic insulating (AFI) regions by including the effect of AF superexchange and weak disorder in the double exchange model. We use a new Monte Carlo technique, mapping on the disordered spin-fermion problem to an effective short range spin model, with self-consistently computed exchange constants. We recover `cluster coexistence' as seen earlier in exact simulation of small systems. The much larger sizes, $\sim 32 \times 32$, accessible with our technique, allows us to study the cluster distribution for varying electron density, disorder, and temperature. We track the magnetic structure, obtain the density of states, with its `pseudogap' features, and, for the first time, provide a fully microscopic estimate of the resistivity in a phase coexistence regime, comparing it with the `percolation' scenario.