High-Tc DC SQUIDs for use in a background field

SQUIDs are the most sensitive magnetic flux sensors currently existing. A dc SQUID consists of a superconducting ring interrupted by two Josephson junctions. An applied flux generates a circulating current in the SQUID ring which causes a voltage over the junctions. Any physical property that can be converted into magnetic flux can be measured by a SQUID. E.g. SQUID magnetometers, accelerometers, galvanometers and picovoltmeters have been realized. Each application requires its own optimization. This thesis treats the development of high-Tc SQUIDs for low frequency magnetometry in an eventual background field. This involves optimization of (multilayer) film technology and junctions and careful design of the SQUID and eventual pick-up arrangements.