Tuning the two-dimensional electron gas at the LaAlO$_{3}$/SrTiO$_{3}$(001) interface by metallic contacts

Density functional theory calculations reveal that adding a metallic overlayer on LaAlO$_{3}$/SrTiO$_{3}$(001) reduces/eliminates the electric field within the polar LaAlO$_{3}$ film and thus suppresses the thickness-dependent insulator-to-metal transition observed in uncovered films. Independent of the LaAlO$_{3}$ thickness both the surface and the interface are metallic, with an enhanced interface carrier density relative to LaAlO$_{3}$/SrTiO$_{3}$ (001) after the metallization transition. Moreover, a monolayer thick metallic Ti-contact exhibits a finite magnetic moment and for a thin SrTiO$_{3}$-substrate induces a spin-polarized 2D electron gas at the $n$-type interface due to confinement effects. The height of the Schottky barrier formed between the metal contact and LaAlO$_{3}$ depends strongly on the choice of the overlayer and allows to tune the carrier density at the interface [1]. \\[4pt] [1] V. Ruiz L\'{o}pez, R. Arras, W. E. Pickett, and R. Pentcheva, arXiv:1106.4205v1.