Pseudogap formation in the metallic state of La0.7Sr0.3MnO3 thin films

We report on scanning tunneling microscopy and spectroscopy (STM/S) studies of epitaxial La0.7Sr0.3MnO3 (LSMO) thin films on a lattice matched (001) La0.3Sr0.7Al0.35Ta0.35O9 substrate for both as-grown and annealed films. In contrast to the as-grown films, the films annealed at 800 °C in air show atomic terraces with spectra that develop a gaplike structure with cooling. We show that the gap structure can be attributed to the predicted pseudogap in the manganites. Unlike several previous reports, we did not find electronic inhomogeneities in LSMO by STM/S.