A new family of field-stable and highly sensitive SQUID current sensors based on sub-micrometer cross-type Josephson junctions

TL;DR

This paper introduces a new family of highly sensitive, field-stable SQUID current sensors utilizing sub-micrometer Josephson junctions, offering low noise, high voltage swings, and broad application potential.

Contribution

The authors develop a novel SQUID current sensor family with sub-micron Josephson junctions, achieving high voltage swings, low noise, and improved reliability under various magnetic fields.

Findings

Low noise of SQUIDs at 4.2 K

Voltage swings exceeding 100 μV

Current sensitivities down to 65 fA/Hz^{1/2}

Abstract

We report on the development of a new family of SQUID current sensors based on sub-micron cross-type Josephson tunnel junctions. Their low total junction capacitance permit high usable voltage swings of more than 100 {\mu}V and exceptional low noise of the SQUIDs at 4.2 K. Integrated rf-filter as well as high tolerable background fields during cool-down of up to 9.6 mT enable their highly reliable and easy use. With input coil inductances ranging from 10 nH to 2.8 {\mu}H and current sensitivities and coupled energy resolution down to 65 fA/Hz^{1/2} and below 10 h, respectively, they are a versatile tool for numerous applications.