Fine "mist" vs large droplets in phase separated manganites

TL;DR

This paper investigates how the size and shape of metallic clusters in phase-separated manganites influence their electrical properties, challenging traditional percolation models by emphasizing cluster distribution effects.

Contribution

It introduces the idea that correlated metallic site occupation leads to larger clusters, explaining hysteresis and thermal cycling effects in manganites beyond simple percolation models.

Findings

Larger metallic clusters cause inverse hysteresis in resistivity.

Cluster size distribution impacts manganite properties.

Thermal cycling effects are linked to cluster formation.

Abstract

The properties of phase-separated systems, e.g. manganites, close to a I order phase transition between charge-ordered insulator and ferromagnetic metal, are usually described by the percolation picture. We argue that the correlated occupation of metallic sites leads to the preferential formation of larger metallic clusters, which explains the often observed inverse, or ``overshot'' hysteresis in manganites (when the resistivity with increasing temperature is larger than with decreasing T). It also explains the recently discovered thermal cycling effect in manganites. Thus in treating this and similar systems in percolation picture, not only the total concentration of metallic phase, but also the distribution of metallic clusters by shape and size may significantly influence the properties of such systems.