Direct Observation of Spectroscopic Inhomogeneities on La0.7Sr0.3MnO3 Thin Films by Scanning Tunnelling Spectroscopy

TL;DR

This study used scanning tunnelling spectroscopy to observe temperature-dependent spectroscopic inhomogeneities in La0.7Sr0.3MnO3 thin films, revealing phase separation near room temperature.

Contribution

It provides direct spectroscopic evidence of inhomogeneities and phase separation in La0.7Sr0.3MnO3 films at room temperature, which was not previously documented.

Findings

Inhomogeneities observed at room temperature but not at liquid nitrogen temperature.

Evidence of phase separation correlating with the metal-insulator transition.

Quantitative analysis of spectroscopic features indicating phase modulation.

Abstract

Scanning tunnelling spectroscopy measurements were performed on La0.7Sr0.3MnO3 thin films both at room temperature and liquid nitrogen temperature. While no inhomogeneities were recorded at liquid nitrogen temperature on any sample, a clear evidence of spectroscopic inhomogeneities was evident in tunnelling conductance maps collected at room temperature. The investigated films exhibit a transition from a ferromagnetic-metallic to a paramagnetic-insulating state around room temperature, so that the observed spectroscopic features can be interpreted within a phase separation scenario. A quantitative analysis of the observed spectroscopic features is reported pointing out the occurrence of phase modulation and its possible correlation with the properties of the system.