Metal-insulator transition in CMR materials

TL;DR

This study investigates the metal-insulator transition in manganite thin films using resistivity measurements and quantum phase transition analysis, concluding that the transition is a finite temperature crossover rather than a continuous quantum phase transition.

Contribution

It provides experimental evidence and analysis suggesting the metal-insulator transition in CMR materials is a finite temperature crossover, challenging the notion of a quantum phase transition.

Findings

Resistivity curves do not show expected scaling for quantum phase transitions.

The metal-insulator transition is likely a finite temperature crossover.

Quantum phase transition framework may not fully describe CMR behavior.

Abstract

We report on resistivity measurements in La$_{0.67}$Ca$_{0.33}$MnO$_{3}$ and Nd$_{0.7}$Sr$_{0.3}$MnO$_{3}$ thin films in order to elucidate the underlying mechanism for the CMR behavior. The experimental results are analyzed in terms of quantum phase transition ideas to study the nature of the metal-insulator transition in manganese oxides. Resistivity curves as functions of magnetization for various temperatures show the absence of scaling behavior expected in a continuous quantum phase transition, which leads us to conclude that the observed metal-insulator transition is most likely a finite temperature crossover phenomenon.