Correlation between extrinsic electroresistance and magnetoresistance in fine-grained La0.7Ca0.3MnO3

TL;DR

This study explores how grain size influences the relationship between extrinsic electroresistance and magnetoresistance in La0.7Ca0.3MnO3, revealing a crossover in charge transport mechanisms at different grain sizes.

Contribution

It demonstrates a correlation between electroresistance and magnetoresistance dependent on grain size, highlighting a transition in charge transport mechanisms.

Findings

Finer grains show similar trends in EER and EMR.

Coarser grains exhibit different behaviors in EER and EMR.

Charge transport mechanism shifts from spin-dependent scattering to spin-polarized tunneling.

Abstract

We report our observation of a correlation between the extrinsic electroresistance (EER) and magnetoresistance (EMR) via grain size in fine-grained La0.7Ca0.3MnO3. The nature of dependence of EER and EMR on grain size (~0.2-1.0 micron) indicates that for finer grains with low-resistive boundaries both of them follow similar trend whereas they differ for coarser grains with high-resistive boundaries. This could be due to a crossover in the mechanism of charge transport across the grain boundaries - from spin-depedent scattering process to spin-polarized tunneling one - as a function of grain size.