Vertical Magnetic Flux Concentrators for High-Sensitivity Superconductor/ Magnetoresistance Composite Sensors

A novel architecture for the superconductor/magnetoresistance (MR) composite sensor with vertical magnetic flux concentrators (MFCs) was studied theoretically and experimentally in this paper, to enhance the sensor's sensitivity and resolution. The three-dimensional finite element method (FEM) of the superconducting flux transformation amplifier (SFTA), characterized by the E-J power law, was firstly established to design and optimize the structure of SFTA with MFCs. Then the influence of the key size of MFCs on the gain factor of SFTA was discussed. Finally, a superconductor/TMR composite sensor with specific-sized MFCs was designed and manufactured. Experimental results showed that the sensitivity was increased by 1.84 times, and the magnetic field resolution was improved from 81 pT/Hz(0.5) to 49 pT/Hz(0.5) by about 1.63 times after setting vertical MFCs, which all accorded with the FEM simulation prediction result of 1.75 times. The work in this paper contributes to the development of high-performance superconductor/MR composite sensors.