Finite size effects and the effect of disorder on electronic phase separation in Pr_(0.5)Ca_(0.5)Mn_(1-x)Al_(x)O_(3)

TL;DR

This study investigates how finite size effects and disorder influence electronic phase separation and magnetic properties in a doped manganite series, revealing disorder-driven stabilization and destabilization of magnetic phases.

Contribution

It demonstrates that disorder stabilizes electronic phase separation and explains the suppression of the CE phase in Pr0.5Ca0.5Mn1-xAlxO3, providing new insights into magnetic phase behavior.

Findings

Self-organized structures driven by phase separation

Magnetic memory effects similar to spin glasses observed

Disorder weakens phase separation and enhances charge mobility

Abstract

We report a bulk magnetisation study of the low temperature magnetic phases in the Mn site substituted half doped manganite series Pr_(0.5)Ca_(0.5)Mn_(1-x)Al_(x)O_(3). Our results indicate the formation of self organised structures in this series of compounds which is driven by electronic phase separation and stabilised by the presence of finite quenched disorder, thus providing a basis for understanding the anomalously large supression of the CE phase in the presence of disorder. Striking magnetic memory effects similar to that seen in spin glasses and interacting superparamagnets are also observed. Increasing disorder is seen to make electronic phase separation weaker owing to the destabilisation of the CE state which results in an enhanced mobility of the charge carriers.