Nonlinear Hall effect and multichannel conduction in LaTiO ₃/SrTiO₃ superlattices

We report magnetotransport 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.