Current-induced metallic behavior in Pr$_{0.5}$Ca$_{0.5}$MnO$_3$ thin films: competition between Joule heating and nonlinear conduction mechanism

TL;DR

This study investigates how current induces metallic behavior in Pr0.5Ca0.5MnO3 thin films, revealing a competition between Joule heating effects and nonlinear conduction mechanisms related to phase separation and thermal instabilities.

Contribution

It demonstrates the coexistence of Joule heating and nonlinear conduction mechanisms in current-induced metallic states of manganite thin films, with a model explaining local thermal instabilities.

Findings

Joule heating affects charge transport at certain temperatures and magnetic fields.

Nonlinear conduction occurs in less resistive samples, not explained by homogeneous heating.

Thermal instabilities linked to phase separation influence the metallic behavior.

Abstract

Thin films of Pr0.5Ca0.5MnO3 manganites exhibiting charge/orbital-ordered properties with colossal magnetoresistance have been synthesized by the pulsed laser deposition technique on both (100)-SrTiO3 and (100)-LaAlO3 substrates. The effects of current-induced metallic-behavior of the films are investigated as a function of the temperature and the magnetic field. Calculations based on a heat transfer model across the substrate, and our resistivity measurements reveal effects of Joule heating on charge transport over certain ranges of temperatures and magnetic fields. Our results also indicate that a nonlinear conduction, which cannot be explained by homogeneous Joule heating of the film, is observed when the material is less resistive (10-2 W.cm). The origin of this behavior is explained with a model based on local thermal instabilities associated with phase-separation mechanism and a change in the long range charge-ordered state.