JPH04330607A - Evaluation method for recording magnetic field of magnetic head - Google Patents

Abstract

PURPOSE:To offer a recording magnetic field evaluation method which can compare the recording magnetic field intensity of a magnetic head in spite of a magnetic pole material. CONSTITUTION:A ferromagnetic film 9 is formed on the exposed surface of a gap 7 in the magnetic head through an insulating layer 10 and the magnetization component of the ferromagnetic film 9 when current is caused to flow in the coil 3 of the magnetic head is detected by using magneto-optical effect, and the generated magnetic field of the head is evaluated by the comparison of the detected value. A minus effect can be used to the utmost as the magneto- optical effect and a thin film consisting of Co, Ni or Fe, or an alloy thin film consisting of them can be used for the ferromagnetic film 9.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a recording magnetic field evaluation method for a magnetic head, and in particular, regardless of the magnetic pole material that constitutes a thin-film magnetic head mounted on a magnetic recording device such as a magnetic disk device or a magnetic tape device. , relates to an evaluation method that allows the evaluation of the recording magnetic field of a single head to be easily performed in a normal atmosphere.

Conventionally, a common method for evaluating the recording ability of a magnetic head is to record information once on a magnetic recording medium and then reproduce the recorded information. However, in this evaluation method using recording media, the macro hysteresis characteristics, film thickness,
Alternatively, since it is greatly influenced by the magnetic properties of the microscopic magnetic material and further by the flying characteristics of the head, it is desirable to have a method that can evaluate the recording ability of the head without using a medium.

0003

2. Description of the Related Art A method using the magneto-optic effect is known as one of the methods for evaluating the recording ability of a magnetic head without passing through a magnetic recording medium. FIG. 3 shows one of the methods for evaluating the recording ability of this conventional magnetic head. This figure shows a thin film magnetic head 20 with its air bearing surface
It is shown in a partial cross-sectional view with the exposed surface of the gap 7 facing upward. In this conventional method of evaluating the recording ability of a magnetic head, the magnetization of the thin film magnetic head 20 is
Measured using the polar Kerr effect.

In FIG. 3, 1 is a lower magnetic pole on a substrate 30 of a floating thin film magnetic head 20, 2 is an upper magnetic pole, and 3 is a lower magnetic pole on a substrate 30 of a floating thin film magnetic head 20.
4 is a coil, 4 is an interlayer insulating layer, 5 is an air bearing surface of the head, 6 is a protective film, 7 is a gap, and 8 is a laser beam incident perpendicularly to the air bearing surface 5 of the head. Laser light 8 linearly polarized perpendicular to the air bearing surface 5 of the head 20
It is well known that when a beam is incident, the reflected light becomes elliptically polarized light due to the magnetization of the head magnetic pole, and the plane of polarization rotates.

On the other hand, the output in the polar Kerr effect is proportional to the magnitude of magnetization. Therefore, by scanning the protective film 6 in the X direction with the laser beam from the substrate 30 side, the detection output Y shown in FIG. 4 can be obtained. This detection output Y increases as the laser beam 8 approaches the lower magnetic pole 1 from the substrate 30, further increases as the laser beam 8 scans over the magnetic pole 1, and becomes maximum at the end of the magnetic pole 1 on the gap 7 side. It decreases above gap 7. When the laser beam 8 passes through the center of the gap 7, the output is reversed, becomes maximum at the end of the upper magnetic pole 2 on the gap 7 side, and gradually decreases as it moves away from the gap 7. Therefore, by reading the peak value V of this detection output, the magnitude of magnetization of the magnetic head can be determined, and the recording capabilities of the heads can be compared with each other.

[0006]

[Problems to be Solved by the Invention] However, in the conventional method of evaluating the recording ability of a magnetic head described above, the Kerr rotation angle of reflected light and the reflectance on the magnetic pole surface are determined depending on the magnetic pole materials used for the magnetic poles 1 and 2. etc., it is possible to compare the recording magnetic field strengths of magnetic heads using the same magnetic pole material, but there is a problem in that it is not possible to compare the recording magnetic field strengths of magnetic heads using different magnetic pole materials.

Therefore, the present invention solves the problems in the conventional method of evaluating the recording ability of magnetic heads, and allows not only comparison of the recording magnetic field strength of magnetic heads using the same magnetic pole material, but also comparison of the recording magnetic field strength of magnetic heads using different magnetic pole materials. It is an object of the present invention to provide a method for evaluating the recording magnetic field of a magnetic head, which also allows comparison of the recording magnetic field strength of the magnetic head.

[0008]

[Means for Solving the Problems] A recording magnetic field evaluation method for a magnetic head according to the present invention that achieves the above object includes forming a ferromagnetic film on the gap-exposed surface of the magnetic head via an insulating layer, and forming a ferromagnetic film on the gap-exposed surface of the magnetic head. The magnetization component of this ferromagnetic film when a current is passed through the head is detected using the magneto-optical effect, and the magnetic field generated by the head is evaluated by comparing the detected values. Note that the polar Kerr effect may be used as the magneto-optical effect, and the ferromagnetic film may be a thin film made of Co, Ni, or Fe, or an alloy thin film made of these components.

[0009]

[Function] According to the recording magnetic field evaluation method of the magnetic head of the present invention, instead of directly evaluating the air bearing surface magnetization by the polar Kerr effect as in the past, a ferromagnetic film serving as a sensor is placed near the air bearing surface, and the magnetic head The surface of the ferromagnetic film magnetized by the magnetic field is irradiated with laser light. Then, it is possible to obtain a Kerr detection voltage that is proportional to the amount of magnetization of the ferromagnetic film, so if ferromagnetic sensor films made of the same material are arranged for heads with different magnetic pole materials, Kerr rotation angle, reflectance, etc. can be obtained. The recording magnetic field of the magnetic head can be evaluated under the same conditions with the same conditions.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 illustrates an embodiment of the recording magnetic field evaluation method for a magnetic head according to the present invention. For the sake of simplicity, the same numbers are given to the same parts as the magnetic head 20 of FIG. 3, which describes a conventional method for evaluating the recording magnetic field of a magnetic head. Therefore, in FIG. 1, 1 is the lower magnetic pole of the thin film magnetic head 20, 2 is the upper magnetic pole, 3 is the coil, 4 is the interlayer insulating layer, 5 is the air bearing surface of the head, 6 is the protective film, 7 is the gap, and 8 is the head. The laser beams incident perpendicularly to the air bearing surface 5 are respectively shown.

In the recording magnetic field evaluation method of a magnetic head according to the present invention, an insulating film 10 is formed with a predetermined thickness on the air bearing surface 5 of the magnetic head 20 by sputtering, and a ferromagnetic film 9 serving as a sensor is further formed. is formed on the insulating film 10 by sputtering, vapor deposition, or plating. In this embodiment, an Al2O3 film with a thickness of 0.1 to 0.2 μm is used as the insulating film 10, and a NiFe film is sputtered as the ferromagnetic film 9.
Formed by vapor deposition or plating.

When current is passed through the coil 3 of the magnetic head 20, the tips of the magnetic poles 1 and 2 are magnetized in the direction shown by the arrow, and the magnetic field generated by the magnetic head 20 also causes the NiFe film 9, which is a ferromagnetic film, to become a sensor. Become magnetized. In this state, a linearly polarized laser beam 8 is perpendicularly incident on the NiFe film 9, and by scanning this from the protective film 6 in the X direction, the polarization state of the reflected wave is detected.

FIG. 2 shows the distribution of the detection output Y obtained as a result of scanning the laser beam 7 in the X direction. This detection output Y is proportional to the magnetization strength of the sensor NiFe film 9 in the vertical direction, and since this magnetization strength is proportional to the magnetic field generated by the magnetic head 20, as the laser beam 8 approaches the lower magnetic pole 1 from the substrate 30, When the laser beam 8 scans over the magnetic pole 1, it becomes even larger, and the gap 7 of the magnetic pole 1 increases.
It is maximum at the side edges and decreases above the gap 7. When the laser beam 8 passes through the center of the gap 7, the output is reversed,
It is maximum at the end of the upper magnetic pole 2 on the gap 7 side, and gradually decreases as it moves away from the gap 7. That is, the detection output Y is ultimately proportional to the magnetic field generated by the head.
This is the Kerr detection voltage of the magnetization intensity in the vertical direction of the Fe film 9.

Therefore, the peak value Vo of this detection output Y
By reading , the magnitude of the magnetization of the magnetic head 20 can be determined, and since the detection output Y is the magnetization strength in the perpendicular direction of the sensor NiFe film 9, recording between the magnetic heads is possible regardless of the type of magnetic pole material of the head. Comparison of abilities can be made.

[0015]

[Effects of the Invention] As explained above, according to the present invention,
This makes it possible to compare the magnetic field strengths generated between heads with different magnetic pole materials, which was extremely difficult using conventional methods, and has the effect of greatly contributing to the development and evaluation of future high-density magnetic heads.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a measurement method using the polar Kerr effect of the present invention.

FIG. 2 is a characteristic diagram showing changes in detection output according to the measurement method of FIG. 1;

FIG. 3 is an explanatory diagram showing a conventional measurement method using the polar Kerr effect.

FIG. 4 is a characteristic diagram showing changes in detection output according to the measurement method of FIG. 3;

[Explanation of symbols]

1...Lower electrode 2...Top electrode 3...Coil 4...Interlayer insulation layer 5... Flying surface of the head 6...Protective film 7...Gap 8...Laser light 9...Ferromagnetic film (NiFe film) 10...Insulating film (Al2O film) 30...Substrate X...Laser light

Claims (1)

[Claims] Claim 1: A ferromagnetic film is formed on the gap-exposed surface of the magnetic head with an insulating layer interposed therebetween, and the magnetization component of this ferromagnetic film when a current is passed through the coil of the magnetic head is determined using the magneto-optic effect. A method for evaluating a recording magnetic field of a magnetic head, comprising: detecting the magnetic field, and evaluating the magnetic field generated by the head by comparing the detected values.