  Cross-sectional scanning tunnelling microscopy and spectroscopy (XSTM/S) were
used to map out the band alignment across the complex oxide interface of
La$_{2/3}$Ca$_{1/3}$MnO$_{3}$/Nb-doped SrTiO$_{3}$. By a controlled
cross-sectional fracturing procedure, unit-cell high steps persist near the
interface between the thin film and the substrate in the non-cleavable
perovskite materials. The abrupt changes of the mechanical and electronic
properties were visualized directly by XSTM/S. Using changes in the DOS as
probe by STM, the electronic band alignment across the heterointerface was
mapped out providing a new approach to directly measure the electronic
properties at complex oxide interfaces.
