Gerald Francis Sauter

Transverse recording using thin film recording heads

This paper presents the results of an investigation of a high density magnetic recording technique utilizing a thin film recording head and a transverse mode of recording on thin media. The significant results of this investigation are as follows. 1) Densities as high as 18 500 transitions per inch were experimentally written in a 300-A thick FeCr medium having an H c of 70 oersteds. 2) These densities were written with a thin film, vapor-deposited, recording head having a MATED-FILM® structure with a 0.4-mil etched gap. 3) Track widths of 1-mil on 2-mil centers were experimentally achieved. 4) Optical readout of a 0.2-mil wide transition (width of beam) region corresponding to 5000 transitions per inch was achieved using a laser beam and a linear motion transport system under ideal experimental conditions. 5) The magnetic field from the Neel wall separating recording domains was detected using a MATED-FILM Etched Gap head making this a possible readout method. Maximum achieved linear bit densities as a function of recording media coercivities are given.

Vapor-deposited thin-film recording heads

A vapor-deposited thin-film recording head and a unique reading technique are described. The head structure used for both write and read is similar to that of the Mated-Film memory element. Conventional longitudinal recordings at 4000 flux reversals per inch have been written with a thin-film head in 300-A-thick iron films having a coercivity of 80 Oe. Conventional longitudinal recordings up to 1600 flux reversals per inch in thin-film media and in oxide media have been sensed with the thin-film head. Although a one-turn sense line is used, flux amplification is obtained because the head magnetization, not the flux from the recording, is sensed. This also results in an output signal that is independent of recording media velocity.

Domain Studies in Thin Film Recording

An observation technique utilizing the longitudinal Kerr magneto‐optic effect was used in various studies of thin film recording. The semitransparent nature of the recording media allowed simultaneous observation of recorded domains and the write and read head gaps. Thin film heads were used to record in iron films having coercivities ranging from 60 to 160 Oe. The apparatus allowed quick determinations of maximum linear densities which were as high as 1550 flux reversals/cm. Recorded domain orientation with respect to the gap of a thin film read head was easily observed, and the corresponding output signals on an oscilloscope were photographed. The write‐read‐observe apparatus with a thin film read head was also helpful in detecting the magnetic field from Neel walls.