JPH02226509A - Magneto-resistance effect head - Google Patents

Abstract

PURPOSE:To obtain a head with high resolution and low crosstalk by setting the width of upper and lower shield layers at values exceeding track width and also, less than the value given by prescribed equation. CONSTITUTION:Assuming the shield width as S, the track width as C, and guard band width as D, it is considered that {(S-C)/(C+D)} tracks other than a track under an MR detecting part exist underneath a shield 6. The value less than -25dB is desirable as the quantity of crosstalk, and since difference (V1-V2) between on-track output and off-track output is 30dB, the shield width S should be set at S<10<1/2>X(C+D)+C for requested track width C and guard band width D. Also, since the shield width S should be larger than the track width C to absorb excessive magnetic flux from the track width C by the shield, it is possible to obtain the head with low crosstalk and suitable for high track density and with high resolution can be obtained by setting the shield width at C<S10<1/2>X(C+D)+C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shielded magnetoresistive head used in magnetic recording devices such as magnetic disk devices and magnetic tape devices.

(Prior Art) Magnetoresistive heads (hereinafter referred to as MR heads) have high reproduction sensitivity and the reproduction output does not depend on the relative speed between the magnetic recording medium and the magnetic head, so they are suitable for use in magnetic recording devices. This device is advantageous for high density and miniaturization. M
In the R head, the magnetoresistive element (hereinafter referred to as MR element) is generally arranged perpendicular to the magnetic recording medium, and directs the component perpendicular to the magnetic recording medium of the magnetic flux generated from the magnetic recording medium. To detect. As an example of an MR head with improved resolution, a shield type MR head in which magnetic shields made of soft magnetic material are placed on both sides of the MR element is known, and is described in IEEE Transactio published in 1975.
ns on Magnetics Magazine No. MAG-11 Volume 12
06 page, JP-A-60-151816, JP-A-63-184906, JP-A-63-50769, etc.

In a shielded MR head, the magnetic shield absorbs the excess magnetic flux emitted from the magnetic recording medium, and increases the MR performance from low linear recording density areas to high linear recording density areas.
The amount of magnetic flux detected by the element becomes approximately constant. Therefore, M.R.
The output voltage reproduced by the element has a constant amplitude from the low linear recording density region to the high linear recording density region, and it is possible to obtain a signal with little waveform interference and no reading errors.

(Problem to be solved by the invention) On the other hand, in order to improve track density, it is effective to reduce the MR detection width, track width, and guard band width, but the relationship between these widths and the shield width has not been clarified until now. It had not been done.

In order to improve the resolution of the MR head by arranging a magnetic shield, it is necessary to make the shield width larger than the MR detection width. However, as the shield width increases, the risk of crosstalk from adjacent tracks increases.

FIG. 3 shows an example of the off-track characteristics of a shield type MR head having an MR detection section with a width of 811 m and a shield with a width of 1100 p.

The off-track characteristics are measured as the reproduction output when a shielded MR head is shifted in the track width direction with respect to a track with a track width of 8 pm and a recording density of 15 KPCI created on a magnetic disk by a recording head. The reproduction output reaches its maximum value when the MR detection section is directly above the track (point X=0 in FIG. 3).

From the off-track characteristics shown in Figure 3, even if the MR detection section and the track are functioning well, if the track is under the shield, magnetic flux will flow to the MR detection section through the shield, causing an output. It can be seen that the output hardly depends on the distance between the MR detection section and the track.

Usually, recording signals are recorded on a plurality of tracks on a medium, as shown in FIG. 4, and each track is separated by a guard band.

Therefore, in a head with a large shield width, outputs from tracks other than the on-track are included as noise, resulting in a head with a large amount of crosstalk. Under the conditions of track width 8pm and guard band 411m,
The amount of crosstalk for a head with the characteristics shown in Figure 3 is -19d.
B, which does not reach -25 dB, which is required from the viewpoint of reliability. Conversely, in order to reduce the amount of crosstalk, it is necessary to increase the track spacing (guard band), which is extremely disadvantageous for increasing recording density.

An object of the present invention is to obtain a head that has the above-mentioned crosstalk smaller than the level required by the device, is suitable for high track density, and has high resolution.

(Means for Solving the Problems) According to the present invention, a structure is provided in which a lower shield layer, a lower inter-shield gap layer, a magnetoresistive element, an upper inter-shield gap layer, and an upper shield layer are laminated on a nonmagnetic substrate. In a magnetoresistive head that reads signals recorded on tracks separated by guard bands on a magnetic recording medium, the width of the upper and lower shield layers is equal to or larger than the track width, and ('v
It is possible to obtain a magnetoresistive head characterized in that Tffx() rack width + guard band width) + track width) or less.

(Function) If S is the shield width, C is the track width, and D is the guard band width, under the shield there is a track ((8-C)/(C+ D)
) It is thought that there is a book truck. As shown in Figure 3,
Since the output v2 from the truck under the shield is almost constant regardless of the distance between the MR detector and the truck,
When the on-track output is Vl, the amount of crosstalk is expressed as decibels = V2-V1+101og ((101o/(C+D))
is given by Therefore, it is desirable that the amount of losstalk is -25 dB or less, and as shown in Fig. 3, the difference between the on-track output and the off-track output, vl - v2, is 3.
Since it is 0 dB, the shield width S is S<qmx(C
+D) +C must be.

Also, in order for the shield to absorb excess magnetic flux from the track width, the shield width S must be larger than the track width C.

From the above two points, by setting the shield width S to C<S<ψX(C+D)+C, it is possible to obtain a shielded MR head with small crosstalk, suitable for high track density, and excellent resolution. I can do it.

(Example) FIG. 1 is a perspective view showing an embodiment of the present invention.

First, a ceramic nonmagnetic substrate (not shown) with a thickness lp
A lower shield 5 made of permalloy of m is formed by a plating method and patterned into a width of 30 pm by ion milling. Thereon, a lower inter-shield gap 7 made of SiO2 with a thickness of 0.4 μm is formed by sputtering. Furthermore, a permalloy MR film 1 with a thickness of 0.0411 m, a current shunt Ti film 2 with a thickness of 0.02 pm,
An MR element in which a Co Zr Mo bias film 3 having a thickness of 0.0511 m is laminated is formed by sputtering.

The CoZrMo film is magnetically coupled with the permalloy film to apply a bias, and the magnetoresistive effect of the permalloy film is detected. The current shunt Ti film 2 is a permalloy MR film 1.
and the CoZrMo bias film 3 are magnetically separated.

Thereon, an electrode 4 made of Au with a thickness of 0.2 pm is formed by vapor deposition, and the MR element and electrode 4 are simultaneously patterned using photolithography and ion etching. Next, the MR element light indicated by 9 ±8 pm
Only the detection portion of the electrode 4 is removed by chemical etching. Furthermore, an upper shield gap 8 using an 8102 film with a thickness of 0.3 pm is formed by a sputtering method, and an upper shield 6 using a permalloy with a thickness of 1 μm is formed by a plating method on top of the gap 8 using a 8102 film with a thickness of 0.3 pm. A pattern with a radius of 30 pm is formed using ion etching technology and ion etching technology.

In this example, the MR detection width is 8 pm, the shield width is 30 μm, and similarly, the shield width is 4.12.
A head with a 20.60 pm was created.

Using these shielded MR heads, track width of 8
The measurement was performed on a disk with a guard band width of Qm and a guard band width of Qm. Under this condition, the range of the shield width S determined by the present invention is 8pm < S < l2VTff + 8pm≠46pm
Therefore, the shield width of 12,20,30 pm was designated as Example 1.2.3, and the shield width of 4.60 pm was designated as Comparative Example 1.2.

15KPCI on on-track, 10KPCI on other tracks
Signals were recorded at the recording density of CI, and the difference in output between the two was measured as the amount of crosstalk using a spectrum analyzer, and the results shown in Table 1 were obtained. From Table 1, the shielded MR head of the embodiment of the present invention has a crosstalk amount of -25 dB or less, and a recording density (D,.) at which the reproduction output is halved is 40 KPCI, and has a high track density. It can be seen that the head has high resolution (high linear density) and low crosstalk. On the other hand, in a head with a shorter shield width than the value determined by the present invention, the D50 is extremely inferior, and in a head with a long shield width, the amount of crosstalk becomes 125 dB or more, resulting in poor performance as a magnetic head. I understand that.

Table 1 Next, as Example 4, an example in which the track width and the MR detection width are not equal is shown.

MR detection width Q created in the same manner as Example 1.2.3
When measuring a disk with a track width of 5 pm and a guard band width of 1 pm using a shielded MR head with a shield width of 10 pm and a shield width of 10 pm, the amount of crosstalk was -3.
2.1 dB, and D5o was 38.4 KPCI. From this example, it can be seen that the present invention is applicable even when the track width and the MR detection width are not equal.

Next, as Example 5, an example using the shunt bias method will be shown. The perspective view shown in Example 5 is FIG. 2. In this embodiment, the MR element is made up only of an MR film 1 made of permalloy and a shunt film 2 made of Ti, and the magnetic field generated by the current flowing through the Ti film becomes the bias magnetic field. Using a shielded MR head with an MR detection width of 8 pm and a shield width of 20 pm, the track width is 811 m and the guard band width is 4 yen.
When measurements were taken on a disc of
It was I. From this example, it can be seen that the present invention is also applicable to a shield type MR head using the shunt bias method.

It goes without saying that the results obtained in the present invention also hold true for bias methods other than the soft film bias method and shunt bias method shown in the Examples.

In the above embodiment, permalloy was used as the shield, but other soft magnetic materials may be used.

(Effects of the Invention) As described above, in the magnetoresistive MR head according to the present invention, a magnetoresistive MR head with small crosstalk, suitable for high track density, and high resolution can be obtained.

[Brief explanation of the drawing]

1 is a perspective view showing a magnetoresistive head according to a first embodiment of the present invention, FIG. 2 is a perspective view showing a magnetoresistive head according to a fifth embodiment of the present invention, and FIG. 3 is a perspective view showing a magnetoresistive head according to a fifth embodiment of the present invention. FIG. 4, which is a diagram showing the track characteristics, is a diagram of the medium and head viewed from a direction perpendicular to the medium surface. In the figure, 1... MR membrane, 2... shunt membrane, 3
...Bias film, 4...Electrode, 5...Lower shield, 6...Upper shield, 7...Gap between lower shields, 8...Gap between upper shields, 9...MR detection Section, 10...truck, 11...guard band.

Claims (1)

[Claims] It has a structure in which a lower shield layer, a lower inter-shield gap layer, a magnetoresistive element, an upper inter-shield gap layer, and an upper shield layer are laminated on a non-magnetic substrate, and on tracks separated by guard bands on the magnetic recording medium. A magnetoresistive head for reading out signals recorded in a magnetoresistive head, characterized in that the width of the upper and lower shield layers is greater than or equal to the track width and less than or equal to {√10×(track width+guard band width)+track width}. Magnetoresistive head.