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

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.