Evidence for charge–vortex duality at the LaAlO3/SrTiO3 interface

The concept of duality has proved extremely powerful in extending our understanding in many areas of physics. Charge–vortex duality has been proposed as a model to understand the superconductor to insulator transition in disordered thin films and Josephson junction arrays. In this model, on the superconducting side, one has delocalized Cooper pairs but localized vortices; while on the insulating side, one has localized Cooper pairs but mobile vortices. Here we show a new experimental manifestation of this duality in the electron gas that forms at the interface between LaAlO3 and SrTiO3. The effect is due to the motion of vortices generated by the magnetization dynamics of the ferromagnet that also forms at the same interface, which results in an increase in resistance on the superconducting side of the transition, but an increase in conductance on the insulating side. Vortex–charge duality is a model that has been proposed for describing the superconducting to insulator transition in disordered thin films. Mehtaet al. report experimental evidence for this duality in the two-dimensional electron gas that arises in LaAlO3/SrTiO3heterostructures.