Investigating superconductor-insulator transition in thin films using drag resistance:Theoretical analysis of a proposed experiment

TL;DR

This paper proposes a theoretical analysis of a new experimental setup involving drag resistance measurements in amorphous thin-film bilayers to clarify the role of quantum vortices in the superconductor-insulator transition.

Contribution

It introduces a novel experimental approach and provides a detailed theoretical analysis to distinguish between competing theories of the transition.

Findings

Vortex paradigm predicts a drag with opposite sign and larger magnitude.

The proposed experiment can decisively identify the correct theoretical framework.

Analysis shows significant differences in drag resistance between paradigms.

Abstract

The magnetically driven superconductor-insulator transition in amorphous thin films (e.g., InO, Ta) exhibits several mysterious phenomena, such as a putative metallic phase and a huge magnetoresistance peak. Unfortunately, several conflicting categories of theories, particularly quantum-vortex condensation, and normal region percolation, explain key observations equally well. We propose a new experimental setup, an amorphous thin-film bilayer, where a drag resistance measurement would clarify the role quantum vortices play in the transition, and hence decisively point to the correct picture. We provide a thorough analysis of the device, which shows that the vortex paradigm gives rise to a drag with an opposite sign and orders of magnitude larger than the drag measured if competing paradigms apply.