Low field magneto-transport in La_0.7Ca_0.3MnO_3-PMMA composites synthesized by polymeric precursor route

TL;DR

This study explores how adding PMMA to La_0.7Ca_0.3MnO_3 affects its structure and magneto-transport properties, revealing increased magneto-resistance and changes in transition temperatures due to intergranular disorder.

Contribution

It introduces a novel polymeric sol-gel synthesis route for La_0.7Ca_0.3MnO_3-PMMA composites and investigates the effects of PMMA on their properties.

Findings

Resistivity increases by two orders of magnitude with more PMMA.

Transition temperature T_C slightly decreases as PMMA concentration increases.

Magneto-resistance significantly enhances at low fields with higher PMMA content.

Abstract

A detailed investigation of the effect of PMMA on the structure, microstructure and magneto-transport properties of manganite La_0.7Ca_0.3MnO_3 (LCMO) is presented. LCMO-PMMA nanostructured composites have been synthesized by a unique polymeric sol-gel route, which leads to improved solubility of PMMA in the LCMO matrix. The LCMO phase is grown in the presence of varying PMMA concentration at ~500 ^0 C. This route yields single phase material and the grain size is observed to decrease slightly with increasing PMMA concentration. On increasing the PMMA concentration, T_C undergoes a small decrease, resistivity is observed to increase by two orders of magnitude, with a concomitant large decrease in T_IM, e.g., from 218 K for virgin LCMO to 108 K for 50 wt% PMMA admixed LCMO. Low field magneto-resistance measured in the temperature range 77-300 K shows considerable enhancement as a function of the PMMA concentration. These phenomena are explained by taking into account the increased intergranular disorder as a consequence of PMMA admixture.