A SQUID magnetometer using a niobium thin-film microbridge

A new type of Superconducting Quantum Interference Device (SQUID) using a submicrometer-width niobium thin-film microbridge on a sapphire substrate is described. This thin-film SQUID is suitable for mass production. It is mechanically rigid and resists mechanical shock and heat cycling. The SQUID is mounted in a niobium two-hole superconductive ring block to decrease its inductance, and an energy resolution of 5 × 10
⁻²⁹
J/Hz is obtained. The paper also describes a magnetometer (comprising this SQUIÜ and gradiometer-type search coils) as well as a magnetically shielded room used to measure magnetocardiograms.