Finite Size Effect in Amorphous Indium oxide

TL;DR

This study investigates how finite size effects influence the magneto-transport properties of amorphous Indium oxide near the superconductor-insulator transition, revealing size-dependent behaviors and crossover phenomena.

Contribution

It provides experimental insights into the finite size effects on the superconductor-insulator transition in amorphous Indium oxide, especially near the 1D limit around 100 nm.

Findings

Resistance increases with decreasing wire width in the superconducting regime.

Wires show a crossover from activated to temperature-independent resistance.

Finite size affects the temperature at which resistance deviates from film behavior.

Abstract

We study the low temperature magneto-transport properties of several highly disordered amorphous Indium oxide(a:InO) samples. Simultaneously fabricated devices comprising a 2-dimensional (2D) film and 10 $\mu$m long wires of different widths were measured to investigate the effect of size as we approach the 1D limit, which is around 4 times the correlation length, and happens to be around 100 nm for a:InO. The film and the wires showed magnetic field ({\it B}) induced superconductor to insulator transition (SIT). In the superconducting side, the resistance increased with decrease in wire width, whereas, an opposite trend is observed in the insulating side. We find that this effect can be explained in light of charge-vortex duality picture of the SIT. Resistance of the 2D film follows an activated behavior over the temperature ($T$), whereas, the wires show a crossover from the high-$T$ activated to a $T$-independent behavior. At high temperature regime the wires' resistance follow the film's until they deviate and became independent of $T$. We find that temperature at which this deviation occurs evolve with magnetic field and the width of the wire, which show the effect of finite size on the transport.