ON THE SENSITIVITY OF HIGH-TC SUPERCONDUCTING CERAMICS AS MAGNETIC-FIELD SENSORS

The granularity of high-temperature superconductors is the limiting factor to most applications, since the intergrain critical currents and fields are extremely low. However, this same feature leads to a potentially important application in magnetometry, using the high sensitivity of the even harmonic terms of the a.c. susceptibility to magnetic fields. A theoretical and experimental study of the sensitivity of high-temperature superconducting materials as magnetic field sensors has been done in the context of critical state models. The feasibility of a magnetometer based on this sensor operating in a negative feedback loop is demonstrated and criteria to optimize its performance to the nT range are given.