High-frequency characterization of Fe-based nanocrystalline cores

Fe-based nanocrystalline alloys like Fe73.5Si15.5Cu1Nb3B7 are commonly used in variable frequency drive systems as electromagnetic interference (EMI) noise absorbers. We study the high frequency magnetic properties of such magnetic alloys employing a well-controlled VNA-based reflectometric method. Our focus is on the dynamic magnetic susceptibility. We developed a coaxial probe head for measuring the magnetic properties of toroid cores up to 1 GHz in addition to a more conventional wired approach. We observe a single-exponential magnetic relaxation in most cases, which obey the Snoek's limit, i.e. the product of the initial permeability and the cut-off frequency is constant. We show that the coaxial probe-head-based approach provides reliable dynamic susceptibility data without the effects of the ill-reproducible wired approach.

Automated summary

This study investigates the high frequency magnetic properties of Fe-based nanocrystalline alloys and observes a single-exponential magnetic relaxation phenomenon using the coaxial probe-head method. Compared to the conventional wired approach, the coaxial probe-head method provides more reliable data on dynamic susceptibility.