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

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.