Electrostatically-tuned superconductor-metal-insulator quantum transition at the LaAlO 3 / SrTiO 3 interface
Résumé
Recently superconductivity at the interface between the insulators LaAlO 3 and SrTiO 3 has been tuned with the electric-field effect to an unprecedented range of transition temperatures. Here we perform a detailed finite-size scaling analysis to explore the compatibility of the phase-transition line with Berezinskii-Kosterlitz-Thouless BKT behavior and a two-dimensional-quantum-phase 2D-QP transition. In an intermediate regime , limited by a gate voltage dependent limiting length, we uncover remarkable consistency with a BKT-critical line ending at a metallic quantum critical point, separating a weakly localized insulator from the superconducting phase. Our estimates for the critical exponents of the 2D-QP-transition, z 1 and ¯ 2 / 3, suggest that it belongs to the three-dimensional-xy universality class.