THIN-FILM MAGNETIC HEAD USING IMPEDANCE CHANGE AT HIGH-FREQUENCY

This article reports on the reproducing characteristics of a new type of thin-film magnetic head, which is based on impedance change due to field dependent permeability at a frequency of several hundred MHz. The head is flux responsive, and a field from a medium is perceived as an amplitude modulation of an AC carrier voltage and reproduced by detection. In order to obtain a large voltage change, the head element is composed of magnetic core/sensing lead/magnetic core sandwich structure, and a NiFe/SiO2 multilayer film structure is adopted for the cores. The lead is also used for a DC bias. A single pole type head and a ring type head, both with this simple core/lead/core structure, were examined for two fundamental operations, and were confirmed to exhibit a differential waveform and an integral waveform, respectively.