JPH07153013A - Thin-film magnetic head for perpendicular magnetic recording - Google Patents

Abstract

PURPOSE:To detect magnetic flux as much as possible which is effective for recording and reproducing by providing yokes on both sides of a main magnetic pole so as to put the main magnetic pole therebetween to reduce the leakage of magnetic flux coming in and out through a medium. CONSTITUTION:A thin-film magnetic head for perpendicular magnetic recording use is constituted of an auxiliary magnetic pole 4, a core 6, a coil 7, a main magnetic pole and the like. A front yoke 2 and a back yoke 8 are provided respectively on both sides of the magnetic pole 1 so as to be in contact with the magnetic pole 1 and to put the magnetic pole 1 therebetween. Thereby, in comparison with the case where the front yoke only is provided, the leakage magnetic flux which does not enter into the magnetic pole 1 is controlled, so that effective magnetic flux is detected more to make a thin-film magnetic head for perpendicular magnetic recording use in which the lowering of a recording and reproducing characteristic is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording head for magnetic recording and reproduction, and more particularly to a thin film magnetic head for perpendicular magnetic recording suitable for use in a perpendicular magnetic recording method having a high magnetic recording density.

[0002]

2. Description of the Related Art In the perpendicular magnetic recording method, recording and reproduction are performed by magnetizing a magnetic layer of a magnetic recording medium in the thickness direction, and recording is performed in comparison with a conventional in-plane magnetic recording method. There is an advantage that the density can be increased. That is, in the in-plane magnetic recording method, the magnetic layer deposited on the magnetic recording medium is magnetized parallel to the surface, and recording / reproduction is performed by the residual magnetization in the in-plane direction.

In the case of this in-plane magnetization, as the recording signal becomes shorter in wavelength, that is, as the recording density becomes higher, the demagnetizing field in the recording medium increases and the residual magnetic flux density is attenuated. Has the disadvantage that it decreases. On the other hand, in the case of perpendicular magnetic recording, such an inconvenience does not occur even if the recording density increases, so that the recording density can be increased as compared with the in-plane magnetization.

FIG. 2 is a schematic diagram showing the structure of a conventional thin-film magnetic head for perpendicular magnetic recording (hereinafter referred to as a vertical thin-film magnetic head). When a signal is written, induced current is generated in a portion (hereinafter referred to as a core) 6 around which the coil is wound by a current flowing through the coil 7, and this magnetic flux is applied to the main magnetic pole 1 and the yoke 2 which assists the flow of the magnetic flux to the main magnetic pole. Flowing. Then, the magnetic flux emitted from the tip of the main pole 1 passes through the recording layer 3 of the medium and flows into the high magnetic permeability layer 4 provided as a base of the recording layer 3. This magnetic flux flows into the auxiliary magnetic pole 5 provided at a distant position behind the main magnetic pole as a magnetic flux return portion, and returns to the core 6. A closed magnetic circuit is configured by the series of magnetic flux flows.

Further, when reproducing a signal, a closed magnetic circuit is created in which the magnetic flux emitted from the medium passes through the main magnetic pole 1, the core 6 and the auxiliary magnetic pole 5 and returns to the medium. At this time, an induced current is generated in the coil 7 by the magnetic flux flowing in the core 6 and is obtained as a reproduction voltage. In such a perpendicular recording method, since the magnetization direction of the medium is the thickness direction of the medium, even if the recording bit becomes small due to the high recording density, there is no inconvenience that the output is lowered due to the influence of the demagnetizing field.

[0006]

However, these conventional thin-film magnetic heads for perpendicular use have a long closed magnetic circuit length in which magnetic flux flows in the perpendicular recording method as described above, so that the amount of magnetic flux is reduced due to leakage of magnetic flux. There is a problem in that the recording and reproducing output is reduced. That is, for example, when recording is performed with the conventional perpendicular thin-film magnetic head, all of the magnetic flux flowing into the main pole 1 and the yoke 2 via the core 6 is
There is a problem in that the recording characteristics are deteriorated because the magnetic flux does not flow into the recording medium through the main magnetic pole 1 and partially leaks to the outside. Further, in the conventional structure of the yoke and the main magnetic pole, there is a problem that the amount of magnetic flux received is limited and the amount of magnetic flux during recording / reproduction cannot be sufficiently increased.

The present invention has been made in view of the above problems, and reduces the leakage of the magnetic flux entering and exiting through the medium, and detects more magnetic flux effective for recording and reproducing, thereby improving the recording and reproducing characteristics. It is an object of the present invention to provide an excellent vertical thin film magnetic head. In order to reduce the leakage of the magnetic flux, the present invention has been completed by studying the shape of the vertical thin film magnetic head and the reduction of the gap between the head and the medium.

[0008]

A vertical thin film magnetic head according to the present invention is a vertical thin film magnetic head having a main magnetic pole and an auxiliary magnetic pole, and yokes for assisting the flow of magnetic flux of the main magnetic pole are provided on both sides of the main magnetic pole. It is characterized in that it is arranged so as to contact and sandwich the main magnetic pole. At this time, the total thickness of the yokes arranged on both sides of the main magnetic pole so as to be sandwiched in contact with the main magnetic pole is preferably 7 μm or less. It is preferable that the difference is 0 to 40% with respect to the length of the longer yoke.

[0009]

According to the present invention, for example, as shown in FIG. 1, a yoke 2 (hereinafter referred to as a front yoke) and a yoke 8 (hereinafter referred to as a back yoke) are arranged so as to be in contact with the main magnetic pole 1 and sandwiched on both sides. Therefore, the magnetic flux from the core 6 can efficiently flow into the main magnetic pole 1 and the yokes 2 and 8 on both sides, and the magnetic flux passing through the yokes 2 and 8 flows into the main magnetic pole near its tip, and in the recording direction. It is possible to create a smooth flow of magnetic flux in a certain vertical direction. As a result, the leakage magnetic flux that does not enter the medium and does not contribute to magnetic recording / reproduction can be reduced, so that the write capability of the perpendicular thin-film magnetic head and the reproduction output can be increased.

The present invention exerts its effect by being arranged so as to be in contact with the main magnetic pole 1 and to be sandwiched on both sides.
Affected by the thickness of the yokes on both sides. That is, the total thickness of the yokes on both sides is preferably 7 μm or less,
More preferably, it is 1 to 6 μm. Further, the thickness ratio of the yokes on both sides also affects the effect, and it is more preferable that the ratio is 5 or less. Further, the difference in length between the yokes on both sides is preferably 0 to 40% with respect to the longer yoke. When it exceeds 40%, its effect is lower than that when it is 0-40%.

[0011]

【Example】

(Examples 1 to 5 and Comparative Example 1) Examples of the present invention will be specifically described below. FIG. 1 schematically shows the structure of a perpendicular thin-film magnetic head according to an embodiment of the present invention (generally, a protective film or the like is further formed on the tip of the perpendicular magnetic head and the recording layer of the medium. Formed, but in Figure 1
It is omitted and shown schematically). The structure is such that a yoke 2 (hereinafter referred to as a front yoke) and a yoke 8 (hereinafter referred to as a back yoke) are arranged in contact with the main magnetic pole 1 and sandwiched on both sides.

The yoke is manufactured by using the core as a core and the coil 7 as a core.
After forming the pattern, the pattern of the back yoke 8 is formed on the coil 7 by photolithography, and then the back yoke 8 is formed to a thickness of 0.5 μm to 10 μm as shown in Table 1.
It was formed by NiFe plating. Although the back yoke 8 is formed into a thin film by plating in this embodiment, vacuum thin film formation such as sputtering may also be used. After lapping the back yoke 8, a main pole pattern was formed by photolithography and CoZrNb was sputtered to form the main pole 1 having a thickness of 0.2 μm. Further, a pattern of the front yoke 2 was formed thereon by photolithography, and then CoZrNb was sputtered to a thickness of 0.5 μm to form the front yoke 2.
The yoke 2 can also be formed by plating with NiFe or the like.

As described above, vertical thin film magnetic heads having the dimensions shown in Examples 1 to 5 and Comparative Example 1 of Table 1 were produced. In Examples 1 to 5 and Comparative Example 1, the thickness of the front yoke 2 was 0.5 μm and the thickness of the back yoke 8 was changed. The overwriting characteristics (O / W characteristics) of these materials were measured by the following method and shown in Table 1.

(Examples 6 to 13 and Comparative Example 2) Further, the thickness of the front yoke was changed to 1.0 μm and the thickness of the back yoke was changed by the same process (Examples 6 to 1).
2 and Comparative Example 2), and the thickness of the front yoke and the back yoke were changed (Example 13). The results of measuring the manufacturing conditions and the overwriting characteristics (O / W characteristics) are also shown in Table 1.

[0015]

[Table 1]

As a result, the O / W characteristics were not good when only the front yoke was used and the back yoke was not used. Further, when the total thickness of the front yoke and the back yoke is 7 μm or more, it takes time to manufacture.

(Examples 14 to 19) Further, by the same process, the length difference (FY-BY) is 0 to 40% with respect to the front yoke having a thickness of 1 μm and a length of 150 μm (Examples).
14-17) was produced. Further, by the same process, the length difference (FY-BY) of the back yoke having a thickness of 1 μm and a length of 150 μm is -30 to -40% (Examples 18 to 19). A vertical thin-film magnetic head having a front yoke and a back yoke was manufactured. Overwriting characteristics (O / W characteristics) and reproduction output (μVpp) of these materials were measured and shown in Table 2.

[0018]

[Table 2]

[Measuring Method of Overwriting Characteristic (O / W Characteristic)] To measure the O / W characteristic, a signal of 2 MHz is first written, an 8 MHz signal is overwritten thereon, and 2 MHz is written.
Measure the remaining portion of the erased signal with a spectrum analyzer. A signal of 2 MHz is written, and the signal intensity measured by the spectrum analyzer is defined as (I ₀ ). Then 2
The 8 MHz signal is overwritten on the MHz signal, and the unerased portion of the 2 MHz signal (I
₁ ) is measured. By (I ₁ −I ₀ ), it is possible to evaluate the ease with which the signal disappears due to overwriting at this time. In this measurement, the relative speed of the disk head was 6 (m / s).

[0020]

As described above, according to the present invention, O
It is possible to obtain a perpendicular thin-film magnetic head having excellent / W characteristics, improved writing ability, and excellent reproduction output.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a structure of a perpendicular magnetic head of the present invention.

FIG. 2 is a schematic view showing an example of a structure of a conventional perpendicular magnetic head.

[Explanation of symbols]

 1 main pole 2 yoke; front yoke 3 recording layer of medium 4 high permeability layer of medium 5 auxiliary pole 6 core 7 coil 8 yoke; back yoke

Claims (1)

[Claims] 1. A thin-film magnetic head for perpendicular magnetic recording having a main magnetic pole and an auxiliary magnetic pole, wherein yokes for assisting the flow of magnetic flux of the main magnetic pole are arranged on both sides of the main magnetic pole so as to contact and sandwich the main magnetic pole. A thin-film magnetic head for perpendicular magnetic recording characterized by.