Ferromagnetic Clusters in the Brownmillerite Bilayered Compounds Ca2.5-xLaxSr0.5GaMn2O8: An Approach to Achieve Layered Spintronics Materials

TL;DR

This study investigates how La-substitution affects magnetic and transport properties of Ca2.5-xLaxSr0.5GaMn2O8, revealing ferromagnetic clusters formation and enhanced magnetoresistance, advancing layered spintronics material development.

Contribution

It introduces a novel approach to induce ferromagnetic clusters in Brownmillerite bilayered compounds through La-substitution, with potential applications in spintronics.

Findings

La-substitution induces ferromagnetic-like behavior

Resistivity decreases with La-substitution

Enhanced magnetoresistance observed in substituted compounds

Abstract

We report the effect of La-substitution on the magnetic and magnetotransport properties of Brownmillerite-like bilayered compounds Ca2.5-xLaxSr0.5GaMn2O8 (x = 0, 0.05, 0.075, and 0.1) by using dc-magnetization, resistivity and magnetoresistance techniques. The Rietveld analysis of the room temperature x-ray diffraction patterns confirms no observable change of average crystal structure with the La-substitution. Both magnetic and magnetotransport properties are found to be very sensitive to the La-substitution. Interestingly, the La-substituted compounds show ferromagnetic-like behavior (due to the occurrence of a double exchange mechanism) whereas, the parent compound is an antiferromagnet (TN 150 K). All compounds show an insulating behavior, in the measured temperature range of 100 - 300 K, with an overall decrease in the resistivity with the substitution. A higher value of magnetoresistance has been successfully achieved by the La-substitution. We have proposed an electronic phase separation model, considering the formation of ferromagnetic clusters in the antiferromagnetic matrix, to interpret the observed magnetization and magnetotransport results for the La-substituted samples. The present study demonstrates an approach to achieve new functional materials, based on naturally occurring layered system like Ca2.5-xLaxSr0.5GaMn2O8, for possible spintronics applications.