High-Tc Superconducting Quantum Interference Filters (SQIFs) made by ion irradiation

TL;DR

This paper demonstrates the fabrication and characterization of high-temperature superconducting SQIFs using ion irradiation, highlighting their robustness and high magnetic field sensitivity for microwave detection.

Contribution

It introduces a scalable ion irradiation method to create high-Tc SQIFs with detailed analysis of their properties and robustness against typical HTSc device asymmetries.

Findings

SQIFs exhibit a transfer function of approximately 1000 V/T.

Devices are robust against asymmetries and spread in Josephson Junction characteristics.

Optimal performance depends on temperature and bias current.

Abstract

Superconducting Quantum Interference Filters (SQIFs) are arrays of superconducting loops of different sizes including Josephson Junctions (JJ). For a random distribution of sizes, they present a non-periodic response to an applied magnetic field, with an extended linear regime and a sizable field sensitivity. Such properties make SQIFs interesting devices to detect the magnetic component of electromagnetic waves at microwave frequencies. We have used the highly scalable technique of ion irradiation to make High Tc SQUIDs and SQIFs based on commercial YBa2Cu3O7 films, and studied their properties. Both display optimum performances as a function of temperature and bias current, that can be understood in the frame of numerical simulations that we developed. The role of asymmetries and spread in JJ characteristics (routinely found in HTSc technologies) is described : ion irradiation based devices appear robust against them. We finally present results on SQIF made with 2000 SQUID in series, showing a transfer function dV/dB ~ 1000V/T .