Polar Discontinuity Doping of the LaVO_3/SrTiO_3 Interface

We have investigated the transport properties of LaVO_3/SrTiO_3 Mott insulator/band insulator heterointerfaces for various configurations. The (001)-oriented n-type VO_2/LaO/TiO_2 polar discontinuity is conducting, exhibiting a LaVO_3 thickness-dependent metal-insulator transition and low temperature anomalous Hall effect. The (001) p-type VO_2/SrO/TiO_2 interface, formed by inserting a single layer of bulk metallic SrVO_3 or SrO, drives the interface insulating. The (110) heterointerface is also insulating, indicating interface conduction arising from electronic reconstructions.