Efficient magnetic shielding by designing layered composite with nanocrystalline and permalloy for weak magnetic measurement

Magnetic field shields are important for ultrahigh-sensitivity sensors and electrical instruments. Traditional single soft magnetic material structures struggle to meet the increasing demands for shielding performance. Here, we develop a multi-layered interfacial composite magnetic shield that further amplifies the interaction by introducing an additional multi-layer nanocrystalline structure on the outer layer of the permalloy to shield low-frequency magnetic fields, including the geomagnetic field, effectively. A theoretical calculation method for the composite magnetic shielding performance that integrates the material properties and structural dimensions is proposed. Using the shielding factor and material thickness as the target, the structure of a three-layer magnetic shielding box is optimized to achieve the expected results. The experimental part was validated using a single-layer N-P composite magnetic shielding box of 400×300×300 mm in length, width, and height with a total thickness of 2.3 mm. The experimental results show that at static magnetic field and AC 1000 Hz, the SF (shielding factor) reaches 593.5 and 652.8, and the measured center remanence is 57.2nT and 52.1nT, respectively. It is hoped that this work can provide an innovative strategy for effective magnetic shielding design.