Two-dimensional quantum oscillations of the conductance at the LaAlO$_{3}$/SrTiO$_{3}$ interface

Electronic states with unusual properties can be promoted at interfaces between complex oxides. A striking example is the interface between the band insulators LaAlO$_{3}$ and SrTiO$_{3}$, which displays conductivity with high mobility and 2D superconductivity. We report on a study of magnetotransport in LaAlO$_{3}$/SrTiO$_{3}$ interfaces characterized by mobilities of the order of several thousands cm$^{2}$/Vs. We observe Shubnikov-de Haas oscillations whose period depends only on the perpendicular component of the magnetic field. This observation directly indicates that the electron gas is two-dimensional and originates from quantum confinement at the interface. From the temperature dependence of the oscillation amplitude we extract an effective carrier mass $m* \simeq$ 1.45$m_{e}$. We discuss the relevance of spin effects on the observed phenomenology.