Scanning tunneling potentiometry search for mesoscopic phase separation in La0.7Sr0.3MnO3

Optimally doped epitaxial La0.7Sr0.3MnO3/SrTiO3 thin films have been probed by scanning tunneling potentiometry in a search for possible mesoscopic phase separation. The experiments were performed in ultrahigh vacuum after an in situ deposition, which prevents local inhomogeneities from forming due to surface contamination. Resulting reproducible two-dimensional images reveal clear topographic features and continuous potentiometric variations. These results support the idea that mesoscopic phase separation is not a generic feature shared by all optimally doped manganites.