Intrinsic Inhomogeneities in Manganite Thin Films Investigated with   Scanning Tunneling Spectroscopy
  Thin films of La0.7Sr0.3MnO3 on MgO show a metal insulator transition and colossal magnetoresistance. The shape of this transition can be explained by intrinsic spatial inhomogeneities, which give rise to a domain structure of conducting and insulating domains at the submicrometer scale. These domains then undergo a percolation transition. The tunneling conductance and tunneling gap measured by scanning tunneling spectroscopy were used to distinguish and visualize these domains. 
T. Becker, C. Streng, Y. Luo, V. Moshnyaga, B. Damaschke, Nic Shannon,   and K. Samwer