Superconductor - Normal and Quantum Superconductor-Insulator Transition at the LaAlO3/SrTiO3Interface

TL;DR

This paper investigates the electric field-tuned superconductivity at the LaAlO3/SrTiO3 interface, providing evidence for a 2D quantum superconductor-insulator transition and analyzing its critical behavior and universality class.

Contribution

It offers new insights into the critical exponents and universality class of the 2D-QSI transition at oxide interfaces, linking experimental data with theoretical models.

Findings

Evidence for a 2D-QSI transition at the interface.

Critical exponents z=1 and nu=3 suggest 3D-xy universality.

Consistency with BKT criticality and weak localization observed.

Abstract

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.