Effect of Hetrovalent substitution at Mn site on the Magnetic and Transport Properties of La$_{0.67}$Sr$_{0.33}$MnO$_3$

TL;DR

This study investigates how substituting Ti at Mn sites in La$_{0.67}$Sr$_{0.33}$MnO$_3$ affects its magnetic and transport properties, revealing that preparation conditions significantly influence the material's behavior.

Contribution

It demonstrates the impact of Ti substitution on magnetic and transport properties under different annealing conditions, highlighting the role of inhomogeneity and formation of magnetic clusters.

Findings

High-temperature annealing suppresses double exchange interaction.

Low-temperature annealing leads to formation of ferromagnetic clusters.

Substitution effects depend on preparation conditions.

Abstract

Magnetic and transport properties of Ti substituted La$_{0.67}$Sr$_{0.33}$MnO$_3$ are drastically affected with a change in preparation conditions. Low temperature infra-red absorption measurements reveal that this is perhaps due to inhomogeniety in substitution of Ti$^{4+}$ on Mn sites. It is found that, in the high temperature annealed samples, the substitution of Ti supresses the double exchange interaction due to the formation of Mn$^{3+}$-O-Ti$^{4+}$ chains. While in the low temperature annealed case substitution of Ti causes formation of isolated ferromagnetic clusters linked to each other by a variable range hopping polaron.