Competing `soft' dielectric phases and detailed balance in thin film manganites

TL;DR

This study investigates the dynamic competition between two dielectric phases in thin film manganites, revealing their thermodynamic balance and supporting the concept of an 'electronically soft' material with continuous phase conversions.

Contribution

It provides detailed measurements of competing dielectric phases and introduces a detailed balance model explaining their thermodynamic and dynamic behavior.

Findings

Identification of two competing dielectric phases

Demonstration of their spatial and temporal competition

Support for the 'electronically soft' material concept

Abstract

Using frequency dependent complex capacitance measurements on thin films of the mixed-valence manganite (La$_{1-y}$Pr$_{y}$)$_{1-x}$Ca$_{x}$MnO$_{3}$, we identify and resolve the individual dielectric responses of two competing dielectric phases. We characterize their competition over a large temperature range, revealing they are in dynamic competition both spatially and temporally. The phase competition is shown to be governed by the thermodynamic constraints imposed by detailed balance. The consequences of the detailed balance model strongly support the notion of an `electronically soft' material in which continuous conversions between dielectric phases with comparable free energies occur on time scales that are long compared with electron-phonon scattering times.