Anomalous Hall Sensors with High Sensitivity and Stability Based on Interlayer Exchange-Coupled Magnetic Thin Films

In this work, we demonstrate that interlayer exchange-coupled magnetic thin films can be employed to fabricate ultrasensitive and thermally stable magnetic sensors, taking advantage of the linear anomalous Hall effect via tuning the interlayer exchange coupling and magnetic anisotropy. We investigate the magnetotransport and noise properties of these anomalous Hall sensors. The magnetic field detectability reaches 126.1 nT/root Hz at 1 Hz and 4.5 nT/root Hz at 1 kHz, at room temperature. Meanwhile, the achieved dynamic reserve is 103.0 dB. The magnetic field detectability shows a good temperature stability in the 200 to 300 K range. Within the temperature range, the temperature coefficient of sensitivity is determined to be 530 ppm/K. The high temperature stability is attributed to the interlayer exchange coupling, which also improves the stability against in-plane magnetic fields, beneficial for perpendicular magnetic field sensing. The interlayer exchange-coupled magnetic thin-film-based anomalous Hall sensors solve the trade-off between the sensor size, sensing capability, and stability, which are desirable for microimaging and biomedical applications.