Thickness-tuned Superconductor-to-Insulator Transitions under magnetic field in a-NbSi

TL;DR

This study investigates how the thickness of a-NbSi thin films influences the superconductor-to-insulator transition under magnetic fields, revealing critical behavior and phase diagrams that challenge existing models.

Contribution

It provides new experimental data on critical exponents and phase diagrams for thickness-tuned transitions in a-NbSi films under magnetic fields, within the dirty boson model framework.

Findings

Critical exponent product $ u_d z$ > 0.4

Phase diagram in (H,d) plane inferred

Non-universal critical resistance observed

Abstract

We have studied the thickness-induced superconductor-to-insulator transition in the presence of a magnetic field for a-NbSi thin films. Analyzing the critical behavior of this system within the "dirty boson model", we have found a critical exponents product of $\nu_d z$ > 0.4. The corresponding phase diagram in the (H,d) plane is inferred. This small exponent product as well as the non-universal value of the critical resistance found at the transition call for further investigations in order to thoroughly understand these transitions.