Micro-Raman and resistance measurements of epitaxial La0.7Sr0.3MnO3 films

TL;DR

This study investigates the effects of oxygen content and annealing conditions on the structural, magnetic, and electrical properties of epitaxial La0.7Sr0.3MnO3 films, demonstrating how optimized fabrication improves their metallic and magnetic behavior.

Contribution

It presents a detailed analysis of how oxygen levels and annealing processes influence the quality and properties of La0.7Sr0.3MnO3 films, using micro-Raman and resistance measurements.

Findings

Oxygen reduces film quality and suppresses Curie temperature.

Vacuum annealing or argon deposition yields high-quality films with metallic behavior.

Micro-Raman indicates well-ordered films with some stoichiometric deviations.

Abstract

The Channel-Spark method was used for deposition of highly oriented ferromagnetic La0.7Sr0.3MnO3 films on NdGaO3 substrates. It was found that additional oxygen decreases the film quality suppressing the Curie temperature and metal-insulator transition below the room temperature. To achieve the best quality of the films the samples were either annealed in high vacuum at deposition temperature or even deposited in argon atmosphere with no oxygen annealing. For such films the resistive measurements showed a metallic behaviour in the interval 10-300 K in accordance with the high Curie point (Tc 350 K). Micro-Raman analysis indicate that the La0.7Sr0.3MnO3 films are well ordered, while some outgrowths show stoichiometrical deviations.