# Hysteretic vortex matching effects in high-$T_c$ superconductors with nanoscale periodic pinning landscapes fabricated by He ion beam projection technique

## TL;DR

This study demonstrates the creation of nanoscale periodic pinning landscapes in YBCO superconductors using He ion beam projection, revealing vortex matching effects and an unconventional critical state with potential for fluxon-based electronics.

## Contribution

It introduces a novel fabrication method for nanoscale pinning arrays in high-$T_c$ superconductors and uncovers unique vortex matching phenomena and critical states.

## Key findings

- Pronounced peaks in critical current at matching fields.
- Displacement of matching peaks in zero-field cooled experiments.
- Stable out-of-equilibrium vortex arrangements observed.

## Abstract

Square arrays of sub-micrometer columnar defects in thin YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ (YBCO) films with spacings down to 300 nm have been fabricated by a He ion beam projection technique. Pronounced peaks in the critical current and corresponding minima in the resistance demonstrate the commensurate arrangement of flux quanta with the artificial pinning landscape, despite the strong intrinsic pinning in epitaxial YBCO films. Whereas these vortex matching signatures are exactly at predicted values in field-cooled experiments, they are displaced in zero-field cooled, magnetic-field ramped experiments, conserving the equidistance of the matching peaks and minima. These observations reveal an unconventional critical state in a cuprate superconductor with an artificial, periodic pinning array. The long-term stability of such out-of-equilibrium vortex arrangements paves the way for electronic applications employing fluxons.