Hybrid Magnetic Sensor Combined with a Magnetic Resistive Sensor and High-Temperature Superconducting Magnetic-Focusing Plates

Magnetic resistive (MR) sensors are widely used; particularly, in consumer products. On the contrary, superconducting quantum interference devices (SQUIDs) are mainly utilized in applications requiring extremely sensitive magnetic sensors. In this study, we developed a hybrid magnetic sensor by combining an MR sensor with two high-temperature superconducting (HTS) plate to achieve the sensitivity that lies half way between the individual sensitivities of the hybrids' component sensors. Two types of magnetic sensors such as an anisotropic MR sensor (AMR) and a nanogranular in-gap tunnel MR sensor (TMR) were separately combined with the HTS plates; next, their magnetic response characteristics were compared. The AMR sensor exhibited lower sensitivity in liquid nitrogen environment, owing to the decreasing effect of temperature on resistivity. The TMR sensor exhibited higher sensitivity, owing to the temperature dependence of the tunneling mechanism. By using the magnetic-focusing characteristic of the HTS plates (manufactured using YBCO) and the slit between the two plates, the sensitivity of both the sensors increased when they were combined with the HTS plates. The adjustment of parameters such as the liftoff between MR sensors, slit of the HTS plates, and plate size allowed for the sensitivity to be controlled, depending on the application.