2D Superconductivity at the LaAlO$_{3}$/SrTiO$_{3}$ interface

In 2004 Ohtomo and Hwang [1] discovered that the interface between two insulating oxides, LaAlO$_{3}$ and SrTiO$_{3}$ (both band insulators), is metallic with a high mobility. This publication triggered a lot of work around the world (see for instance [2, 3]). We have studied the ground state of this system and discovered superconductivity [4]. The studied LaAlO$_{3}$ samples are grown epitaxialy by pulsed laser deposition on TiO$_{2}$-terminated SrTiO$_{3}$ substrates and are annealed in situ in oxygen. The superconducting properties in the LaAlO$_{3}$/SrTiO$_{3}$ heterostructures display signatures of 2D superconductivity and agree with the Beresinskii-Kosterlitz-Thouless (BKT) predictions. However, for low currents, IV curves show some deviation from the expected behavior of a perfect infinite 2D system. These deviations are attributed to the finite lateral size of the measured path. Experiments to probe this size effect have been done to check this interpretation. \newline \newline [1] A. Ohtomo, H. Y. Hwang, Nature \textbf{427}, 423 (2004) \newline [2] S. Thiel, G. Hammerl, A. Schmehl, C. W. Schneider, J. Mannhart, Science \textbf{313}, 1942 (2006) \newline [3] A. Brinkman \textit{et al}, Nature Materials \textbf{6}, 493 (2007) \newline [4] N. Reyren \textit{et al}, Science \textbf{317}, 1196 (2007)