High-Shielding Coefficient and Low-Noise of Cobalt-Based Metallic Glass Magnetic Shielding Cylinder

High-shielding coefficient and low-noise magnetic shielding systems play an important role in the field of ultrahigh-sensitive magnetic field sensors and biomagnetism measurements. Currently, the magnetic shielding systems often suffer from high intrinsic magnetic noise generated by μ-metal. In this study, cobalt-based metallic glass with high permeability and excellent soft magnetic properties was employed to design magnetic shielding cylinders with an inner diameter of 240 mm. Using the finite element method (FEM) simulation, the shielding coefficient S of the single-layer cobalt-based metallic glass (20 μm thickness) magnetic shielding cylinder was 11.27 for the geomagnetic field. The magnetic noise characteristics of cobalt-based metallic glass magnetic shielding cylinder were analyzed based on complex permeability and resistivity in the obtained frequency band. In addition, we also experimentally studied the effectiveness of cobalt-based metallic glass magnetic shielding cylinder with different layers, when used as the innermost magnetic shielding layer, in suppressing the magnetic noise generated by μ-metal. The experimental results show that the minimum magnetic noise of the ten-layer cobalt-based metallic glass magnetic shielding cylinder is only 1.3 fT/Hz^1/2, which indicates that cobalt-based metallic glass as an innermost magnetic shielding layer material can effectively reduce the magnetic noise generated by μ-metal and verifies the superiority of cobalt-based metallic glass in achieving low noise. Moreover, the ultrathin structure and low cost of the cobalt-based metallic glass magnetic shielding cylinder offer significant advantages for other applications requiring the measurement of extremely weak magnetic fields. This study confirms the potential of cobalt-based metallic glass in improving the performance of magnetic shielding systems.