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.
@article{arxiv.0808.3043,
title = {Correlation between extrinsic electroresistance and magnetoresistance in fine-grained La0.7Ca0.3MnO3},
author = {P. Sujatha Devi and A. Kumar and Dipten Bhattacharya and Shilpi Karmakar and B. K. Chaudhuri},
journal= {arXiv preprint arXiv:0808.3043},
year = {2010}
}