A method of manufacturing a magnetic head that includes a reproducing head, a recording head, and an isolation film for magnetically isolating the reproducing head and the recording head from each other. The method includes the steps of: forming the reproducing head; forming the recording head; and forming the isolation film. The isolation film is formed by stacking a plurality of insulating films formed by chemical vapor deposition.

Method of manufacturing a thin-film magnetic head

Using a micro-Kerr magneto-optic apparatus, magnetization curves of thin film heads were measured. Relationships between repeatability of the magnetization process and readback wave form distortion were examined. In yokes made of positive magnetostriction NiFe the trianglar edge domains were found to be large, the magnetization process was not repeatable and readback wave form distortion was observed. For negative magnetostrictive yokes, the edge domains were smaller, the magnetization process was repeatable and wave form distortion was not observed.

Measurements of magnetic characteristics of thin film heads using magneto-optical method

The domain structures of cores patterned in thin film heads for disk drive systems were investigated by using spin-polarized SEM. This method made it possible to determine the direction of the magnetization at the domains and domain walls in magnetic cores accurately. Domain structures in the track width, as small as 10 μ m could be observed. Domain structure could also be observed at the tapering area of a thin film head. It was found that the triangular domains without the closure domains are located at the edge of the magnetic core in single- and six-layered permalloy films in some cases. Such a domain structure was regarded as causing the wiggles in the read-out waveforms.

Magnetic domains of permalloy films for magnetic recording thin film heads observed by spin-polarized SEM

Domain wall networks, their motions and transformations are studied in response to changing magnetic fields (≤ 30 Hz) in small, rectangular, easy-axis and hard-axis stripes of Permalloy film (375A). Many of the effects reported previously using Bitter solution or Lorentz techniques are now seen optically in real time with a wide-field, high resolution, polarized, laser magneto-optic microscope system. This initial study reports optical detection of transformations between domain configurations such as the Landau-Lifshitz structure (L.L.), L.L. plus diamond, concertina, and bellows. Wall cluster and subcluster artifacts are visible and may be seen to generate (annihilate) or bifurcate (amalgamate) during network motion.

https://ieeexplore.ieee.org/iel5/20/22883/01064551.pdf

Magneto-optic observation of domain motions and instabilities in small permalloy elements

We describe a new dynamic response behavior of domain walls in the permalloy of thin‐film inductive heads. A laser magneto‐optic microscope (LAMOM) which enhances the longitudinal Kerr effect, is used to image Bloch lines (BLs) within the 180° walls by aligning the optical plane of incidence perpendicular to these walls. BLs are visible due to the reversal in the Neel‐type surface components of the wall magnetization at the BL position. Current pulses with fast transition times and ac currents within the frequency range of 1–10 MHz are applied to the integrated coil windings. Continuous excitation induces either a continuous flowing of the wall network or a temporary displacement. When individual pulses are applied, displacements of BLs are observed. Correlation of wall displacements with the BL displacements is demonstrated for some pulsed excitations.

Bloch line influence on wall motion response in thin‐film heads

In a thin-film magnetic recording head, a magnetic circuit made from two Permalloy thin films, one above the other, is magnetized by a spixally plated thin-film copper coil which is located (together with insulating layers) between those two films. The magnetic domains in a thin Permalloy film can be studied by type-2 magnetic constrast using backscattered electrons (BSE) in the scanning electron microscope (SEM) provided that the film has a smooth surface and is deposited on a flat substrate. In practice, the upper Permalloy film follows the contours of the underlying layers. This gives a topographic signal which is large enough to mask the type-2 magnetic contrast signal in its simple form. The domain walls can, however, be seen if the magnetic recording head is excited with a sinusoidal current and if the video waveform is processed with a lock-in amplifier referenced either to the fundamental or to the second harmonic of the excitation frequency. This lock-in image processing technique has now been applied to obtain images of the magnetic domains both from the upper Permalloy film of an incompletely fabricated head and also from the exposed cross sections of the Permalloy films in an operational thin-film head.

O. Wells

Papers

Magnetic domains in thin-film recording heads as observed in the SEM by a lock-in technique