Integrated HTS dc-SQUID magnetometers

Abstract

Integrated magnetometers based on superconducting quantum interference devices (SQUIDs) are employed for the very sensitive measurement of magnetic flux and magnetic flux density. Today, most superconducting magnetometers made from high-temperature superconductors (HTS) are based on YB_a2Cu₃O₇ and are optimized for a temperature of 77 K. Depending on the application, the size of the magnetometers is restricted. Many applications in the non-destructive evaluation (NDE) of materials allow the use of large chips with up to 5 cm diameter. The need for integrated, multilayer magnetometers arises, when high sensitivity has to be combined with high spatial resolution with areas below 1 cm². This applies to the sensors in multichannel systems for biomagnetism which have to be adapted to the size of the sources of magnetic signals in the human heart or brain. Here, a survey on the current status of integrated, thin-film YB_a2Cu₃O₇ magnetometers is given.