Superconducting Transition and Vortex Pinning in Nb Films Patterned with Nano-scale Hole-arrays

TL;DR

This study demonstrates how nano-scale hole arrays in Nb films significantly enhance vortex pinning and produce observable matching effects in magnetization and critical temperature oscillations, especially at low temperatures and high fields.

Contribution

It introduces a method of patterning Nb films with nano-scale holes using AAO substrates, leading to enhanced flux pinning and pronounced matching effects in superconducting properties.

Findings

Flux pinning is increased by two orders of magnitude in patterned samples.

Pronounced matching effects observed up to 9 kOe.

Matching effects dominate vortex pinning at 4.2 K.

Abstract

Nb films containing extended arrays of holes with 45-nm diameter and 100-nm spacing have been fabricated using anodized aluminum oxide (AAO) as substrate. Pronounced matching effects in the magnetization and Little-Parks oscillations of the superconducting critical temperature have been observed in fields up to 9 kOe. Flux pinning in the patterned samples is enhanced by two orders of magnitude as compared to unpatterned reference samples in applied fields exceeding 5 kOe. Matching effects are a dominant contribution to vortex pinning at temperatures as low as 4.2 K due to the extremely small spacing of the holes.