  First principles calculations reveal that adding a metallic overlayer on
LaAlO3/SrTiO3(001) eliminates the electric field within the polar LaAlO3 film
and thus suppresses the thickness-dependent insulator-to-metal transition
observed in uncovered films. Independent of the LaAlO3 thickness both the
surface and the interface are metallic, with an enhanced interface carrier
density relative to LaAlO3/SrTiO3(001) after the metallization transition.
Moreover, a monolayer thick metallic Ti-contact exhibits a finite magnetic
moment and for a thin SrTiO3-substrate induces a spin-polarized 2D electron gas
at the n-type interface due to confinement effects. A diagram of band alignment
in M/LaAlO3/SrTiO3(001) and Schottky barriers for M=Ti, Al, and Pt are
provided.
