Vortex crossing, trapping and pinning in superconducting nanowires of a NbSe$_2$ two-dimensional crystal

TL;DR

This study investigates vortex dynamics in NbSe₂ 2D superconducting nanowires, revealing how vortex crossing, trapping, and pinning influence magnetoresistance patterns, with potential for tuning via surface modifications.

Contribution

It provides the first detailed experimental analysis of vortex behavior in 2D NbSe₂ nanowires, linking vortex dynamics to magnetoresistance features and demonstrating control through surface adsorbates.

Findings

Vortex crossing rate varies non-monotonically with magnetic field.

Magnetoresistance patterns are sample-specific and act as a vortex pinning fingerprint.

Surface adsorbates can modify local pinning potentials.

Abstract

Nanowires of two-dimensional (2D) crystals of type-II superconductor NbSe$_2$ prepared by electron-beam lithography were studied, focusing on the effect of the motion of Abrikosov vortices. We present magnetoresistance measurements on these nanowires and show features related to vortex crossing, trapping, and pinning. The vortex crossing rate was found to vary non-monotonically with the applied field, which results in non-monotonic magnetoresistance variations in agreement with theoretical calculations in the London approximation. Above the lower critical field, $H_{c1}$, the crossing rate is also influenced by vortices trapped by sample boundaries or pinning centers, leading to sample-specific magnetoresistance patterns. We show that the local pinning potential can be modified by intentionally introducing surface adsorbates, making the magnetoresistance pattern a "magneto fingerprint" of the sample-specific configuration of vortex pinning centers in a 2D crystal superconducting nanowire.