  Interface engineering is an extremely useful tool for systematically
investigating materials and the various ways materials interact with each
other. We describe different interface engineering strategies designed to
reveal the origin of the electric and magnetic dead-layer at La0.67Sr0.33MnO3
interfaces. La0.67Sr0.33MnO3 is a key example of a strongly correlated
peroskite oxide material in which a subtle balance of competing interactions
gives rise to a ferromagnetic metallic groundstate. This balance, however, is
easily disrupted at interfaces. We systematically vary the dopant profile, the
disorder and the oxygen octahedra rotations at the interface to investigate
which mechanism is responsible for the dead layer. We find that the magnetic
dead layer can be completely eliminated by compositional interface engineering
such that the polar discontinuity at the interface is removed. This, however,
leaves the electrical dead-layer largely intact. We find that deformations in
the oxygen octahedra network at the interface are the dominant cause for the
electrical dead layer.
