Scientists have recently developed a low-noise magnetic sensor that retains high sensitivity and improves weak-field detection, providing a new approach to overcoming the long-standing trade-off between sensitivity and noise in magnetic sensors.

The sensor was developed by researchers from the High Magnetic Field Laboratory at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences (CAS), together with collaborators from Ningbo Institute of Materials Technology and Engineering of CAS, and Eastern Institute of Technology.

The relevant findings were published in Physical Review Letters on July 17.

Magnetic sensors with high sensitivity are essential for applications including automotive electronics, industrial inspection, and biomedical imaging. However, improving sensor sensitivity often comes at the cost of increased noise, which limits their ability to detect extremely weak magnetic signals.

In this study, the research team established a theoretical model that links magnetic sensor noise to the microscopic dynamics of spin textures—the nanoscale magnetic structures governing sensor behavior. The model shows that low-frequency noise decreases as the characteristic frequency of spin-texture dynamics increases.

Based on this mechanism, the researchers designed a synthetic ferrimagnetic structure with faster spin-texture dynamics to suppress noise. By adjusting magnetic anisotropy near the spin-reorientation regime, they further enhanced sensor sensitivity while reducing noise, breaking the conventional sensitivity–noise limitation.

The resulting sensor, with an active sensing area of only 20 μm × 20 μm, achieved a magnetic-field detectivity of 15.7 nT/√Hz at 1 Hz. This performance is nearly one order of magnitude better than that of sensors based on conventional ferromagnetic materials.

According to the researchers, the findings provide a new strategy for developing high-performance magnetic sensors, with potential applications in weak biomagnetic signal detection and high-resolution magnetic imaging.

Harnessing spin-texture dynamics in synthetic ferrimagnets for low-noise, high-sensitivity magnetic sensors. (Image by WANG Kang)