ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Magnetoimpedance (MI) in Co-based amorphous alloys has been shown to be a very sensitive, quick-response new method for measurements of magnetic fields. At present, the experimental results on MI in amorphous wires are obtained for frequencies f〈200 MHz. For quick-response magnetic heads used in high density magnetic recording, the carrier current frequency of the MI element is needed to be increased up to 1 GHz to detect recorded signals of 50–100 MHz. Here we present the experimental data on MI in CoFeSiB amorphous wires for a broad waveband of 1–1200 MHz. The experimental technique is based on the measurement of the complex reflection coefficient from a coaxial waveguide having an amorphous wire as an internal conductor. This method avoids the radiation effects, inevitable at high frequencies, f(approximately-greater-than)100 MHz, in simpler techniques utilizing an oscilloscope or an impedance analyzer with a lead wire. From the data on reflection coefficient, the real and imaginary parts of the wire impedance Z and permeability μ are found as functions of a frequency and an external longitudinal field. The impedance versus field behavior changes with increasing the frequency. For f〈1 MHz the absolute value of the impedance ||Z|| decreases with increasing the field. As the frequency is increased, a maximum appears in the impedance-field dependence. In the case of high frequencies, f(approximately-greater-than)800 MHz, ||Z|| increases with the field. For all frequencies, a higher sensitivity is seen in small fields less than 2 Oe. The sensitivity has a maximum of about 100%/Oe at the frequency of 600 MHz, and it is still very high (∼20%/Oe) up to f∼1 GHz. These results are in satisfactory agreement with the theoretical ones based on the skin effect in a magnetic wire with a tensor rotational permeability. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.361936
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