  The synthesis of materials with well-controlled composition and structure
improves our understanding of their intrinsic electrical transport properties.
Recent developments in atomically controlled growth have been shown to be
crucial in enabling the study of new physical phenomena in epitaxial oxide
heterostructures. Nevertheless, these phenomena can be influenced by the
presence of defects that act as extrinsic sources of both doping and impurity
scattering. Control over the nature and density of such defects is therefore
necessary, are we to fully understand the intrinsic materials properties and
exploit them in future device technologies. Here, we show that incorporation of
a strontium copper oxide nano-layer strongly reduces the impurity scattering at
conducting interfaces in oxide LaAlO3-SrTiO3(001) heterostructures, opening the
door to high carrier mobility materials. We propose that this remote cuprate
layer facilitates enhanced suppression of oxygen defects by reducing the
kinetic barrier for oxygen exchange in the hetero-interfacial film system. This
design concept of controlled defect engineering can be of significant
importance in applications in which enhanced oxygen surface exchange plays a
crucial role.
