  We report magneto-transport properties of heterointerfaces between the Mott
insulator LaTiO3 and the band insulator SrTiO3 in a delta-doping geometry. At
low temperatures, we have found a strong nonlinearity in the magnetic field
dependence of the Hall resistivity, which can be effectively controlled by
varying the temperature and the electric field. We attribute this effect to
multichannel conduction of interfacial charges generated by an electronic
reconstruction. In particular, the formation of a highly mobile conduction
channel revealed by our data is explained by the greatly increased dielectric
permeability of SrTiO3 at low temperatures, and its electric-field dependence
reflects the spatial distribution of the quasi-two-dimensional electron gas.
