Superconductivity at the interface between the insulators LaAlO3 and SrTiO3 has been tuned with the electric field effect. The data provide evidence for a two dimensional quantum superconductor to insulator (2D-QSI) transition. Here we explore the compatibility of this phase transition line with Berezinskii-Kosterlitz-Thouless (BKT) behavior and a 2D-QSI transition. In an intermediate regime, limited by a finite size effect, we uncover remarkable consistency with BKT- criticality, weak localization in the insulating state and non-Drude behavior in the normal state. Our estimates for the critical exponents of the 2D-QSI-transition, z =1 and nu=3, suggest that it belongs to the 3D-xy universality class.
@article{arxiv.0807.0774,
title = {Superconductor - Normal and Quantum Superconductor-Insulator Transition at the LaAlO3/SrTiO3Interface},
author = {T. Schneider and A. D. Caviglia and S. Gariglio and N. Reyren and D. Jaccard and J. -M. Triscone},
journal= {arXiv preprint arXiv:0807.0774},
year = {2008}
}