JPH0512846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for manufacturing a main magnetic pole of a perpendicular magnetic recording head (hereinafter referred to as a perpendicular head), in which the magnetic properties of a high magnetic permeability thin film used for the main magnetic pole are controlled during the production of the thin film. The purpose of this is to increase the reliability of the vertical head and improve its performance by making it isotropic.

In recent years, with the demand for higher density magnetic recording, the so-called perpendicular magnetic recording method, which performs magnetic recording in the thickness direction of a magnetic recording medium, has been attracting attention.

Various types of vertical heads have been proposed for use in perpendicular magnetic recording, but basically they consist of a main pole made of a thin film with high magnetic permeability, a relatively thick auxiliary pole made of ferrite, etc., and an excitation coil. It is structured accordingly.

Among these vertical heads, a typical auxiliary pole excitation type vertical magnetic head is shown in FIG. In this head, during recording, a recording current is passed through the coil 2 to excite the auxiliary magnetic body 3, and the interaction between the excited high permeability thin film 1 of the main pole and the perpendicular magnetic medium 5 occurs. record. 7 is a head support stand.

Further, during reproduction, a reproduction current flows through the coil 2 through a process reverse to that during recording, and this is detected and utilized.

Now, in these cases, since the magnetization reversal of the main pole occurs along the initial magnetization curve of the high magnetic permeability thin film 1,
This initial magnetization curve is important as a characteristic of the perpendicular magnetic head, and is closely related to the magnetic anisotropy of the thin film 1. FIG. 2 shows examples of hysteresis curves 6 and 8 and initial magnetization curves 7 and 9 on the easy axis and hard axis of magnetization (hereinafter simply referred to as easy axis and hard axis) of the thin film 1.

Since the magnetization process in the easy axis direction is due to domain wall movement, the maximum magnetic permeability in the initial magnetization curve 7 is large, but the magnetic permeability at high frequencies is rather small because the magnetization reversal speed is slow.

Furthermore, since the magnetization process in the hard axis direction is due to the rotation of the magnetic axis of the magnetic domain, the magnetization reversal speed is much faster than in the easy axis direction. Therefore, although the maximum magnetic permeability in the initial magnetization curve 9 is smaller than that in the easy axis, the decrease in magnetic permeability at high frequencies is small.

On the other hand, the magnetic properties required of the high permeability thin film of the main magnetic pole are mainly two points: (a) good responsiveness to high-speed reversal of magnetic flux, and (b) high reproduction sensitivity. For the reasons mentioned above, regarding (a), the faster the magnetization reversal speed is, the better, which is advantageous for the difficult axis, and regarding (b), the higher the magnetic permeability, the better, which is advantageous for the easy axis. Because of these contradictory properties, it is not possible to use either the hard axis or the easy axis independently, and by making the magnetic properties so-called isotropic, where the hard axis and easy axis coexist, magnetization reversal in the hard axis can be achieved. Ideally, it should be used in a state where the speed is maintained while the playback sensitivity is increased.

Figure 3 shows hysteresis curve 10 in isotropy.
and its initial magnetization curve 11 are shown.

Conventionally, in order to obtain the characteristics shown in FIG. 3, a high magnetic permeability thin film produced by a sputtering method, vapor deposition method, plating method, etc. was annealed in a rotating magnetic field to make it isotropic.

However, with this method, the magnetic properties of the thin film sensitively respond to changes in the environment during the creation of the highly permeable thin film, resulting in subtle changes, so even when annealing is performed in a rotating magnetic field, the magnetic properties of the thin film obtained are uneven. Reproducibility was poor.

Further, the annealing temperature also differs depending on the high magnetic permeability material, but since it is necessary to raise it to about 300 to 1100°C, heating and cooling take time.

The present inventor focused on solving these problems, and found that when applying a magnetic field perpendicular to the thin film while forming a high magnetic permeability thin film, the magnetic properties of the formed high magnetic permeability thin film can be easily changed to isotropic. I found that it was a target. The reason for this is not yet well understood, but by applying a vertical magnetic field during film formation, the easy axis of the high magnetic permeability thin film grows nearly perpendicular to the surface of the substrate, that is, the head support. However, the perpendicular magnetization condition Hk4πMs (Hk
The grown film cannot have an easy axis in the direction perpendicular to the substrate because it does not satisfy the uniaxial magnetic anisotropy energy in the perpendicular direction and Ms is the saturation magnetization. As a result, the direction of magnetic anisotropy becomes random depending on the size of each crystal grain, and as a result, it is presumed that the grown film becomes isotropic.

Examples of the present invention will be described below.

Embodiment 1 As shown in FIGS. 4a, b, and c, a magnet 14 having a magnetization axis in a direction perpendicular to the substrate is placed directly below the substrate 13.
were arranged to have the distribution of magnetic lines of force shown in Figure 4c.
Permalloy film (78%N, 22%Fe) obtained by high frequency sputtering using this substrate holder
FIG. 5 shows an example of the hysteresis curve.

Embodiment 2 As shown in FIGS. 6a, b, and c, a donut-shaped yoke 17 made of a high magnetic permeability material with a circular hole in the center,
A magnet 14' is arranged around the substrate holder 12, with the substrate 13 being sandwiched between the magnets 17'. At this time, magnet 1
The magnetism of 4' is set so that the pole faces the surface in contact with the high permeability yokes 17, 17', and the position of the substrate is such that the film forming surface is made of high permeability material on the upper and lower sides, as shown in Figure 6c. By arranging the yoke 17, 17' between the yokes 17 and 17', the lines of magnetic force 15 on the surface of the substrate can be uniformly directed perpendicular to the surface of the substrate. A permalloy film (78%N, 22%
An example of the hysteresis curve of Fe) is shown in Fig. 7.

It was confirmed that the hysteresis curves of both the permalloy films prepared in Example 1 and Example 2 did not change even when the magnetic field was rotated in the in-plane direction in the B-H tracer. As a result, it is considered that there is no magnetic anisotropy in the in-plane direction and the material is isotropic. As described above, according to the present invention, a high magnetic permeability thin film that is isotropic and has excellent magnetic properties can be easily produced with good reproducibility.

However, in this embodiment, the size, polarity, and shape of the magnets 14, 14' and the material and shape of the yoke plates 17, 17' made of a high magnetic permeability material are such that the lines of magnetic force 15 are The present invention is not limited to this embodiment, as long as it is uniformly oriented in a direction perpendicular to the plane.

[Brief explanation of the drawing]

FIG. 1 is an example of a typical vertical head. Second
The figure shows typical hysteresis curves and initial magnetization curves on the easy axis and hard axis of magnetization. FIG. 3 shows a hysteresis curve and an initial magnetization curve in the case of isotropy without magnetic anisotropy. FIG. 4 shows Example 1 of the present invention, in which a is a front view, b is a cross-sectional view, c is a distribution of magnetic lines of force, and FIG. 5 is an example of a hysteresis curve of the obtained high magnetic permeability thin film. FIG. 6 shows Example 2 of the present invention, in which a is a front view, b is a cross-sectional view, c is a distribution of magnetic lines of force, and FIG. 7 is an example of a hysteresis curve of the obtained high magnetic permeability thin film. 1: Main magnetic pole, 2: Coil, 3: Auxiliary magnetic pole, 4:
Base film, 5: Perpendicular magnetic medium, 6: Easy axis hysteresis curve, 7: Head support. (Second
In the figure, the initial magnetization curve of the easy axis), 8: Hysteresis curve of the hard axis, 9: Initial magnetization curve of the hard axis, 10: Hysteresis curve in isotropy, 1
1: Initial magnetization curve in isotropy, 12: Substrate holder, 14, 14': Magnet, 15: Line of magnetic force, 1
7, 17': Yoke plate made of high magnetic permeability material.

Claims (1)

[Claims] 1. When forming the main magnetic pole of a perpendicular magnetic recording head in the form of a thin film of Permalloy on the surface of the head support using the sputtering method, lines of magnetic force are applied perpendicularly to the surface of the head support. A method for producing a main pole of a perpendicular magnetic recording head, which is characterized by obtaining a thin film having isotropic magnetic properties. 2. A method for producing a main pole of a perpendicular magnetic recording head according to claim 1, characterized in that a magnet is used along the back surface of the head support. 3. A method for making a main pole of a perpendicular magnetic recording head according to claim 1, characterized in that the head support is disposed within a magnetic circuit using a magnet and a yoke plate made of a high magnetic permeability material.