Magnetic Thermometer for High-Resolution 10-mK Scale Thermometry

A thin-film magnetic thermometer with integrated, superconducting quantum interference device (SQUID) readout has been designed for fast, precision temperature measurements in the 10-mK range. The compact magnetic thermometer consists of a miniature DC SQUID susceptometer with a dilute paramagnetic alloy deposited in one of the two series-configured, gradiometric SQUID pickup loops that form the SQUID inductance. Directly sensing the magnetic signal with the SQUID eliminates coupling losses that occur by transformer-coupling the signal to a remotely located SQUID, usually operating at a higher temperature, and consequently, with a higher noise floor.