Characteristics of a thick high-critical temperature superconductor film used as a highly sensitive magnetic sensor

In the construction of a highly sensitive magnetic sensor, the thick superconducting high-critical temperature superconductor (HTS) film will generally break the superconducting state of current flow at a value of current density J_ms greater than that of the critical current density J_c , when the resistance R_ms of the film to the flow of current occurs in the absence of an excitation magnetic field. The magnetic sensitivity S of the sensor when exposed to an excitation magnetic field, was found to be about 200%/(10^-4 T) for Bi-Pb-Sr-Ca-Cu-O (BPSCCO) magnetic sensor, and about 7%(10^-4 T) for Y-Ba-Cu-O (YBCO) magnetic sensor. That is, the magnetic sensitivity of the BPSCCO magnetic sensor is about 200 times greater than that of a giant magnetoresistance (GMR) sensor. Furthermore, after measurements through more than 300 thermal cycles between temperatures of 77.4 K and 300 K, the characteristics of the thick BPSCCO film magnetic sensor were found to exhibit no significant changes in magnetic response. The present paper reveals the dependencies of R_ms on the temperature T, of resistivity ρ of the thick film on J_ms, of R_ms on the applied excitation magnetic field B_ex, and the dependence of S on the ρ.