Power - law resistivity behavior in 2 D superconductors across the magnetic field - tuned superconductor - insulator transi - tion

– We present the results of a systematic study of thin-films of amorphous indiumoxide near the superconductor-insulator transition. We show that the film’s resistivity follows a simple, well-defined, power-law dependence on the perpendicular magnetic field. This dependence holds well into the insulating state. Our results suggest that a single mechanism governs the transport of our films in the superconducting as well as insulating phases. At temperatures (T s) near the absolute zero, the superconductor-insulator transition (SIT) in two-dimensional systems is a dramatic phenomenon. Over a rather narrow stretch of parameters, such as magnetic field (B) or film thickness, the resistivity (ρ) swings from being immeasurably low, essentially zero, to being exponentially diverging with lowering T [1]. One does not expect, given this large disparity in the behavior of ρ, that a unified description of transport in these two opposing regimes should exist. It is therefore surprising that a theoretical framework was developed, in which this common description naturally emerges [2,3]. Since the insulator and the superconductor are two distinct T = 0 phases of the electronic system, the SIT is considered as a quantum phase transition (QPT), driven by a parameter in the Hamiltonian that can, in principle, be controlled in experiments [4]. Within this framework the resistivity, in both the superconducting and insulating phases, is described by a single universal scaling function that is expected to be relevant in the vicinity of the transition. Evidence for, and against, the validity of the QPT approach to real samples has been reported in the literature [5–11]. The purpose of this Letter is to show that the resistivity of our superconducting amorphous indium-oxide (a:InO) films can be described by a single function covering a wide range of our (∗) E-mail: [email protected]