Effect of substrate-induced strain on transport and magnetic properties of epitaxial La_0.66Sr_0.33MnO_3 thin films

TL;DR

This study investigates how substrate-induced strain affects the electrical and magnetic properties of La_0.66Sr_0.33MnO_3 thin films, revealing strain-dependent phase behavior and proposing a microscopic model for analysis.

Contribution

It introduces a microscopic model that accounts for Jahn-Teller and bulk strain effects on manganite thin films, contrasting with traditional approaches.

Findings

Large Jahn-Teller strain induces semi-conducting/insulating states below Curie temperature.

Electrical and magnetic properties strongly correlate with strain.

Proposed model incorporates e_g orbitals and strain effects on transition temperature.

Abstract

We have studied electrical transport and magnetic properties of epitaxial La_0.66 Sr_0.33 Mn O_3 thin films grown on different substrates having different lattice strains induced by different film-substrate lattice-mismatch. Both electrical transport and magnetic properties exhibit strong correlation with Jahn-Teller strain. Our study shows a sufficiently large Jahn-Teller strain giving rise to distinct semi-conducting/insulating state in LSMO thin films even below the respective para-ferromagnetic Curie temperatutes Tc, which is in contradiction with the established phase diagram of Sr-doped manganites. We have presented a microscopic model for the analysis of our data instead of the usual expansion around the undistorted state generally in use in the literature. The model incorporates the two relevant e_g orbitals (and their ordering thereof) and the effect of both Jahn-Teller and bulk strain on the transition temperature via double exchange.