Insulating phase in two-dimensional Josephson junction arrays investigated by nonlinear transport

Understanding the properties of the insulating phase is key to uncovering the nature of the superconductor-insulator quantum phase transition. Here, the authors study two-dimensional Josephson junction arrays, a canonical model system of the superconductor-insulator transition, to clarify how the insulating phase develops. By systematic studies of nonlinear transport properties, they show that the formation of the insulating phase upon decreasing temperature is understood as the localization of Cooper pairs caused by the Berezinskii-Kosterlitz-Thouless mechanism under the influence of a finite-range screening of the interaction between Cooper pairs.