JPS6020802B2 - magnetic head - Google Patents

Description

Detailed Description of the Invention The present invention relates to a magnetoresistive element (hereinafter referred to as M
It is called an R element.

) is used as a reproducing head. The MR element is a reproducing magnetic head (hereinafter referred to as an MR head).

) In recent years, many attempts have been made to use it as a method. FIG. 1 schematically shows the structure of an MR head commonly used at present. FIG. 1-A shows a basic configuration diagram, and FIG. 1-B shows a more specific configuration. In FIG. 1-A, the M old element 2 is arranged perpendicularly to the recording medium 1 and allows a detection current 1 to flow between terminals 3 and 3'.

The magnetization M of the MR element 2 is caused by the leakage magnetic field from the medium 1.
The direction of the detected current 1 is tilted by an angle a from the magnetically stable direction (due to the inherent magnetic anisotropy and shape anisotropy, the direction of the detected current 1 is normally the stable direction), a resistance change occurs due to a change in the magnetization state, and the current 1 is detected as a voltage change between terminals 3 and 3'. More practically, as shown in Figure 1-B, M
The R element 2 is inserted with magnetic shielding materials 4 and 4', and a bias magnetic field is applied for the purpose of operation in the linear region. degree) A configuration that keeps it tilted can be explored. In the MR head having such a configuration, when the distance between the magnetic shields 4 and 4' becomes small, leakage magnetic flux from the medium is absorbed by the magnetic shield materials 4 and 4'.
4', and the magnetic field no longer acts effectively on the MR element 2. Also, when the length of the M calm element 2 in the detection current direction is reduced to narrow the track, the resistance of the MR element itself There are drawbacks such as a decrease in the value and therefore a decrease in the detection signal based on the resistance change.

In order to maintain a high signal level, there is a method of increasing the detection current, but this increases heat generation, and a method of increasing the resistance by reducing the thickness of the MR element deteriorates manufacturing stability. There is a problem. SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic head in which an MR element effectively absorbs leakage magnetic flux from a medium, and in which a detection signal based on a change in resistance does not decrease even when the track is narrowed.

That is, the present invention has a structure in which an MR element, a bias mechanism for the M-helix element, and a pair of high permeability magnetic bodies installed above and below are layered on a substrate in a direction perpendicular to the substrate surface. In this magnetic head, the M rudder element is provided sufficiently long from the leading end of the head to the rear end or its vicinity, and the current terminal is provided so that the signal detection current of the MR element flows in a direction perpendicular to the surface of the recording medium. This is a magnetic head having a structure.

The present invention will be explained in detail below using the drawings.

FIG. 2 shows an embodiment of the present invention. FIG. 2-A shows a cross section in the direction perpendicular to the substrate 11.
A high permeability magnetic material 14 and a thin insulating layer 16 are laminated thereon.
A high magnetic permeability magnetic material 12, which is to serve as an MR element, is placed on top of it.
The conductors 13, 13', which are to be current terminals, are ohmic-coupled with the high permeability magnetic material 12, except for the area where resistance changes are to be detected. An insulating layer 17, a high coercive force magnetic material 15 that generates a bias magnetic field, an insulating layer 18, and a high permeability magnetic material 14' are further laminated.

Figure 2-B is 15, 17, 18, 14' of Figure 2-A.
It shows a plan view of the part excluding. In this example, MR
Since the element is made sufficiently long in the direction perpendicular to the recording medium surface, even if the interval between the high magnetic permeability magnetic bodies 14 and 14' for magnetic shielding is reduced, the M old element can sufficiently absorb leakage magnetic flux. Can be done.

Further, the signal detection current 1 flows between 13 and 13' in a perpendicular direction to the surface of the recording medium, and the magnetization M of the MR element 12 is directed so as to form an angle of 8 (345 degrees) with the currents 1 by the bias magnetic field. As a result, another feature of this embodiment is that by making the direction of the signal detection current perpendicular to the recording medium surface,
Area where resistance change should be detected (13, 13' in Figure 2-B)
(area sandwiched between the hatched areas) becomes longer, and the amount of total resistance change can be increased. In the configuration of Figure 1-A, the overall resistance value decreases as the track decreases, and as a result, the amount of resistance change proportional to this decreases, and therefore the output value decreases. It is possible to have a configuration that is unaffected by Ochu. That is, as the inside of the track becomes smaller, the inside of the tip of the MR element 12 located under the terminal 13' facing the recording medium is made into the middle of the track,
It increases as the distance from the medium increases, and in the area where the resistance change is to be detected, it can be kept constant regardless of the length of the track.

In this case, of course, the conductor to be the terminal 13' should cover the entire area whose inside is being changed. In addition, the dimension in the middle direction of the region where the resistance change is to be detected can be set to an appropriate dimension so that the demagnetizing field when magnetized in the middle direction is not too large and the overall resistance value does not decrease significantly. The head with the configuration shown in FIG. 2 according to the present invention is relatively less affected by the demagnetizing field.
It can be seen that an excellent magnetic head is obtained which is not significantly influenced by the dimensions within the track. Next, another embodiment of the present invention is shown in FIG. In FIG. 3, the high magnetic permeability magnetic material 24, insulating layer 26, and MR element 22 are laminated on the substrate 21 in the same manner as in FIG.
Thus, a portion of the high magnetic permeability magnetic material forming the M-crotch element 22 is exposed and directly magnetically coupled to the high magnetic permeability magnetic material 24'. The advantage of exploring such a configuration is that by forming a closed magnetic circuit with the MR element 22, the high permeability magnetic material 24', and the recording medium,
The magnetic flux passes through the M old element more easily than in the configuration shown in FIG. Therefore, the head according to the embodiment of the present invention shown in FIG. 3 effectively picks up magnetic flux and provides a head with a large amount of resistance change, that is, a large reproduction output. Regarding the embodiments of FIGS. 2 and 3 of the present invention, the following modified configurations are also possible.

First, if the substrates 11 and 21 are high permeability magnetic materials, the high permeability magnetic materials 14 and 24 are unnecessary. Furthermore, the substrate 11,
If 21 is an insulating high permeability magnetic material, the insulating layers 16 and 26 can be omitted together with the high permeability magnetic materials 14 and 24. Second, even if the high permeability magnetic materials 14 and 24 are conductive, in FIG.
In FIG. 3, it is also possible to remove either the portion of the insulating layer 26 directly below the conductor 23' or the portion directly below the conductor 23, respectively, and combine the MR element with the high permeability magnetic material below. This further enhances the effects of the heads of the embodiments shown in FIGS. 2 and 3, respectively.

Although FIGS. 2 and 3 show a structure using a high coercive force magnetic material as a bias mechanism, it is of course possible to use a conductor and bias the MR element by a current magnetic field.

FIG. 4 shows an example of a structure in which a conductor current magnetic field is used as a bias magnetic field. In Figure 4, the second
A conductor forming a terminal 33' corresponding to 13' in the figure and 23' in FIG. There is. The magnetic head having the structure shown in FIG. 4 has the advantage that a bias magnetic field is generated by the signal detection current itself, and the number of current terminals is only two. If they are not connected at 33', a total of four current terminals and two power supplies are required. Also, if you try to set the bias current and signal detection current to different values, the number of terminals will be three because it is possible to combine at 33', but you will still need two power supplies. . Therefore, the magnetic head according to the embodiment of the present invention shown in FIG. 4 provides an excellent magnetic head that requires a minimum number of terminals and a minimum power supply.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a conventional MR head, and FIGS. 2 to 4 are examples of the present invention.

1, 19, 39... Recording medium, 2, 12, 22, 32.
... High permeability magnetic material for MR element, 11, 21, 31
・・・・・・Substrate, 4, 4', 14, 14', 24, 2
4', 34, 34'... High permeability magnetic material, 6, 16, 1
7, 18, 26, 27, 28, 36, 37, 38...
... Insulating layer, 5, 15, 25 ... High coercive force magnetic material for bias, 3, 3', 35 ... 0 terminal, 13
, 13', 23, 23', 33, 33'...Conductor for current terminal, M...Magnetization of MR element, 1...
...Signal detection current, 8...Angle formed by M and 1.

Oh figure 2 figure Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A magnetoresistive element, a bias mechanism for applying a bias magnetic field to the magnetoresistive element, and a pair of high permeability magnetic bodies provided above and below, with these elements inserted, are mounted on a smooth substrate. In a magnetic head having a structure in which the magnetic heads are stacked in a direction perpendicular to the substrate surface, the magnetoresistive element extends from the tip of the magnetic head facing the recording medium surface to the rear end farthest from the recording medium surface or its vicinity. 1. A magnetic head characterized by having a structure in which current terminals are provided continuously and such that the direction of the signal detection current to be passed through the magnetoresistive element is perpendicular to the surface of the recording medium. 2. In the magnetic head according to claim 1,
The magnetoresistive element is electrically insulated from the pair of high permeability magnetic materials in the region where the resistance change is detected, and is electrically insulated from the pair of high permeability magnetic materials in at least a part of the region outside the region where the resistance change is detected. A magnetic head that is in contact with one of the high permeability magnetic materials. 3. In the magnetic head according to claims 1 and 2, one of the conductors forming the current terminal is passed through an insulating layer over a region in which a resistance change of the magnetoresistive element is to be detected, and a signal detection current is detected. A magnetic head that doubles as a bias current.