Effect of in-plane line defects on field-tuned superconductor-insulator transition behavior in homogeneous thin film

TL;DR

This paper investigates how in-plane line defects influence the superconductor-insulator transition in 2D thin films, revealing conditions under which the critical resistance vanishes and identifying a quantum metallic phase.

Contribution

It demonstrates that line defects aligned parallel with random positions can cause the critical resistance to vanish, resembling 1D quantum transitions, and identifies a quantum metallic phase in certain defect configurations.

Findings

Critical resistance vanishes in systems with line defects under parallel current.

1D-like critical behavior appears with weaker point disorder.

Quantum metallic behavior emerges with finite correlation length of line defects.

Abstract

Field-tuned superconductor-insulator transition (FSIT) behavior in 2D isotropic and homogeneous thin films is usually accompanied by a nonvanishing critical resistance at low $T$. It is shown that, in a 2D film including line defects paralle to each other but with random positions perpendicular to them, the (apparent) critical resistance in low $T$ limit vanishes, as in the 1D quantum superconducting (SC) transition, under a current parallel to the line defects. This 1D-like critical resistive behavior is more clearly seen in systems with weaker point disorder and may be useful in clarifying whether the true origin of FSIT behavior in the parent superconductor is the glass fluctuation or the quantum SC fluctuation. As a by-product of the present calculation, it is also pointed out that, in 2D films with line-like defects with a long but {\it finite} correlation length parallel to the lines, a quantum metallic behavior intervening the insulating and SC ones appears in the resistivity curves.