Field-stable SQUID magnetometer with sub-fT Hz^{− 1/2}resolution based on sub-micrometer cross-type Josephson tunnel junctions

Abstract

We report on the development of a new family of magnetic field sensors with exceptionally low magnetic field noise, as low as 0.3 fT Hz − 1/2. Beside this, they exhibit high usable voltage swings of more than 150 µVpp and tolerable background fields during cool-down of up to 6.5 mT. In operation mode they recover completely from magnetization pulses of up to 76 mT, which makes them well suited for applications such as low-field magnetic resonance imaging. With respect to their easy and reliable use as well as their field resolution in the sub-fT Hz − 1/2 range, the presented SQUID sensors are adequate for many applications, such as in geophysics or in biomagnetism.