Abrupt $PbTiO3/SrTiO3$ superlattices grown by reactive molecular beam epitaxy

$PbTiO3/SrTiO3$ superlattices were grown on (001) $SrTiO3$ substrates by reactive molecular beam epitaxy (MBE). Sharp superlattice reflections were observed by x-ray diffraction. High-resolution transmission electron microscopy of a $[(PbTiO3)10/(SrTiO3)10]15$ superlattice revealed that the $PbTiO3/SrTiO3$ interface structure is atomically sharp. The superlattice interfaces are fully coherent; no misfit dislocations or other crystal defects were observed in the superlattice by transmission electron microscopy. Selected area electron diffraction patterns indicated that the $PbTiO3$ layers are oriented with the c axis parallel to the growth direction. The dimensional control and interface abruptness achieved in this model system indicate that MBE is a viable method for constructing oxide multilayers on a scale where enhanced dielectric effects are expected.