Normal state and superconducting transport at the LaAlO$_{3}$ / SrTiO$_{3}$ interface

The conduction at the LaAlO$_{3}$/SrTiO$_{3}$ interface [1] provides a playground for controlling metallicity and superconductivity in a thin electron gas. This can be achieved by varying the growth of the LaAlO$_{3}$ layer, the thickness [2], and by field effect modulation [3]. A crucial question is whether the variation in conductivity is due to changes in the carrier density or mobility. Using magnetotransport studies of a gated structure, we find that the mobility variation is almost five times that of the sheet carrier density. Superconductivity can be suppressed at both positive and negative gate bias [4]. These results indicate that the relative disorder strength strongly increases across the superconductor-insulator transition. \\[4pt] [1] A. Ohtomo and H.Y. Hwang, Nature \textbf{427} 423 (2004) \\[0pt] [2] C. Bell \textit{et al.}, Appl. Phys. Lett. \textbf{94}, 222111 (2009) \\[0pt] [3] A. Caviglia \textit{et al.}, Nature \textbf{456} 624 (2008) \\[0pt] [4] C. Bell \textit{et al.}, Phys. Rev. Lett. (in press)