High-Frequency Measurement of the Magnetic Inductance Caused by a Current Flowing Through Fe-Co-Based Amorphous Wires

The magnetic inductance obtained by feeding a current through Fe-Co-Si-B amorphous wires with near-zero negative magnetostriction was measured at frequencies between 0.5 kHz and 13 MHz. It was found that an as-quenched Fe-Co based wire (Co94) having nearly zero magnetostriction (of the order of -10-7) exhibited a bamboo-shaped domain structure and an inductance of 9 μH/cm at frequencies up to 10 kHz. It was also found that the magnetostriction of the same Fe-Co base wire was shifted in the positive direction by annealing and that the bamboo-like domain structure of the wire with near-zero magnetostriction acquired a maze-like domain structure. A more Co-rich wire (Co95) was fabricated, to take account of the change in magnetostriction. It is shown that the more Co-rich wire retains the bamboo-like domain structure after annealing and exhibits a fairly large inductance of 60 μH/cm at 1 kHz and 20 μH/cm at 10 kHz; the latter figure is 2.3 times larger than that of a so-called cross-inductor.