Low magnetic noise, easy-to-process polystyrene-grafted amorphous alloy composites for extremely-weak magnetic measurement at ultra-low frequency

Cobalt-based amorphous alloys (Co-MG) demonstrate ultra-high permeability and remarkably-low power loss, positioning them as promising candidates for shielding (near-) static magnetic fields and addressing accuracy limitations in extremely-weak magnetic measurements. However, the brittleness and poor understanding about magnetic performance below 100 Hz have impeded their widespread adoption. To integrate satisfied processing, magnetic and mechanical performances, polystyrene-grafted Co-MG composites are developed. Compared with permalloy-1J85, Co-MG-(g-PS_35 %) composite exhibits 40 % increase in initial permeability, 48 % increase in saturation magnetization, 71 % reduction in remanence within shielding area. In contrast to Mn–Zn ferrite, Co-MG-(g-PS_35 %) composite demonstrates the power loss and μ″/μ′² values lower by an order of magnitude, resulting in magnetic noises 85 % lower at 1 Hz. Furthermore, the resultant composite maintains similar processing-rheological behaviors and mechanical properties compared with bulk polystyrene. It provides an innovative solution to expand real-world applications for biomagnetic detection, and overcome the sensitivity limitation of extremely-weak magnetic measurement.