JPH0410209A - Magnetoresistive playback head - Google Patents

Abstract

PURPOSE:To obtain a magnetic head having simple constitution reducing Barkhausen noise by letting a current flow to three conductors by using two power sources. CONSTITUTION:As the structure of a conductor layer, electrodes 1b and 1d are connected by a bypass conductor part 3 to form the recessed lower conductor layer, and an electrode 1a is connected to the lower conductor layer by a conductor part 4a or an electrode 1c is connected to the lower conductor layer by a conductor part 4b. Further, the electrodes 1a and 1c are electrically in contact with an MR layer 2. When using the magnetic head, for example, the electrodes 1b and 1c are connected to a zero potential, the electrode 1a is connected with a positive potential and the electrode 1d is connected with the constant current source having a negative potential. By this connection, the current flows in the three kinds of routes as follows; the first route is through the MR element 2, the electrode 1c and the conductor part 4b to the electrode 1d so that the change of a voltage between the electrodes 1a and 1c can be an MR output, the second is through the conductor part 4a and a bypass conductor part 3 to the electrode 1d and the third is from the conductor part 4a to the electrode 1b. In this case, since the negative potential is applied to the electrode 1d, the current simultaneously flows from the electrode 1c to the 1d.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention provides a magnetic head suitable for high-density magnetic recording in a magnetic recording device. [Conventional technology 1] A magnetoresistive reproducing head (hereinafter referred to as MR head) passes a constant current (sense current) through a magnetoresistive element (hereinafter referred to as MR element) to generate a signal magnetic field at both ends of the MR element. This is a magnetic sensor that detects voltage changes. The signal magnetic field rotates the magnetization within the MR element, and when the angle between the magnetization and the sense current is θ, the mechanism is such that a voltage change proportional to cos2θ is generated across the MR element. When actually used as a magnetic head, it is necessary to provide an angle of θL: 45° in advance in order to increase the output voltage. One method is to provide a conductor layer adjacent to the MR element and apply a bias magnetic field in the difficult direction of the MR element by passing a current in the direction of easy magnetization of the element. At this time, the direction of easy magnetization in the MR element and the direction of the detection current are made to match, and the bias magnetic field in the difficult direction is controlled to provide an optimal magnetization angle. There is another problem in practical use. This is Barkhausen noise caused by an unstable magnetization state within the MR element. The track width of recording media such as magnetic tape devices is several 1
If it is 0 μm, that is, if the aspect ratio (the ratio of the length of the element in the track width direction to the height of the element in the direction perpendicular to the medium) can be made sufficiently large, the magnetization state in the MR element can be changed to a different shape. It was possible to stabilize it by adjusting the orientation. However, as the tracks become narrower due to higher recording densities, stabilization of the magnetization state due to shape anisotropy is no longer expected. Therefore, it has become necessary to actively stabilize the magnetization by applying a bias magnetic field in the direction of easy magnetization of the MR element. 1
One method is to form a conductor layer that interlinks with the direction of easy magnetization of the MR element, and to generate a bias magnetic field by passing a current through the conductor layer. However, in order to obtain the necessary magnetic field, a current of about several 100 mA is required, and it is best to apply a uniform magnetic field. Furthermore, as a result of adopting the bias method as described above, a sense current power supply and a bias power supply in two directions are required, respectively, resulting in a problem that the device configuration becomes complicated. In addition, as a conventional example related to the present invention, Japanese Patent Laid-Open No. 56-1
65924, JP-A-59-121616, and the like. [Problems to be Solved by the Invention] An object of the present invention is to make it possible to apply a uniform bias magnetic field in the direction of easy magnetization of an MR element in order to reduce Barkhausen noise, while simplifying the number of required power supplies. That's true.

[Means to solve the problem]

forming conductor layers interlinking with both ends of the MR element in the direction of easy magnetization, a part of each conductor layer electrically contacting the ends of the MR element in the direction of easy magnetization, and further adjacent to the MR element; Moreover, the above object is achieved by providing a bypass conductor layer between two conductor layers so that a current flows in parallel to the direction of easy magnetization. [Operation] The operation of the present invention will be explained using FIGS. 1 and 2. 1st
The figure is a circuit diagram showing the basic configuration of the present invention, and FIG. 2 is a perspective view of the main part of a magnetic head according to an embodiment of the present invention. The conductor layer structure according to the present invention is shown in FIG. Electrodes 1b and 1d are connected by a bypass conductor part 3 to form a concave lower conductor layer, and electrode 1a is connected to the lower conductor layer by a conductor part 4a, or electrode 1c is connected to the lower conductor layer by a conductor part 4b. Furthermore, the electrodes 1a and 1c are in electrical contact with the MR film 2. When actually using the magnetic head of the present invention. For example, the electrodes 1b and 1c are connected to zero potential, 1a is connected to a constant current source of positive potential, and 1d is connected to a constant current source of negative potential. With such a connection, the current flowing from the power source to the electrode 1a takes the following three paths. One path is a path that flows to the electrode 1d via the MR element 2, the voltage ViLc, and the conductor portion 4b (path 1). Here, electrode 1
The change in voltage between 8.10 and 10 is the MR ratio output. The second is the electrode 1d via the conductor part 4a and the bypass conductor part 3.
(route 2). The current flowing through the bypass conductor section 3 applies a magnetic field in the direction in which the MR element is difficult to magnetize. By controlling the electrical resistance of the bypass conductor section 3, it is possible to adjust the current value and generate an optimal magnetic field. The third is a path flowing from the conductor portion 4a to the electrode 1b (
Route 3). Here, since a negative potential is applied to the electrode 1d, current also flows from the electrode 1c to the electrode 1d at the same time. Since the current flows in the directions from 1a to 1b and from 1c to 1d, magnetic fields in the same direction are generated at both ends of the MR element in the direction of easy magnetization. Here, in order to reduce the gradient of the magnetic field applied to the MR element, the potential of the electrode 1d is determined so that the current values of the electrodes 1a and 1c closest to the MR element are made equal. Due to this effect, a uniform magnetic field is applied to the entire MR element. (Example) The manufacturing order of the electrode conductor layer and the MR element part will be explained using FIG. Film thickness 0.2μ
It is Cu of m. The conductor pattern was formed using ordinary photolithography technology. Next, SiO2 (not shown) with a film thickness of 0615 μm is laminated as an insulating layer, and subsequently, through holes for the conductor portions 4 are formed. The conductor part 4 is made of Cu, which is the same as the lower conductor, and the height is <0.1, which is the same as the insulating layer.
It is 5 μm. Subsequently, the MR film 2 is deposited. In this example, the MR film has a thickness of 0.04 μm, a length of 16 μm, a height of 8 μm, and a track width of 4 μm.
18Fe was used. After depositing the MR film 2, the electrodes 1a and I
C is laminated to complete the formation of the MR element and electrode portion. In this example, a constant current source of +60 mA is connected to the electrode 1a, and 10 mA and 30 mA are connected to the path 1, path 2, and path 3, respectively.
A, determine the resistance ratio of each electrode and conductor layer so that 20 mA flows, and the same current of <60 mA as electrode 1a flows through electrode 1.
A constant current source of -100 mA was connected to the electrode 1d so that the current was flowing at the electrode 1d. In this example, the resistance ratio was controlled by changing the pattern width of the conductor layer. However, as a method of controlling the resistance value, for example, the conductor parts 4a and 4b are made of W, Nb, Mo, etc.
There are a method of laminating metals with different resistivity from u and a method of connecting a resistor between the electrode and the power source. Figure 3 shows the spatial distribution of the magnetic field generated from the conductor interlinking with the MR element.Curve a in the figure shows that when a current is passed through the conductor for applying a magnetic field in the difficult-to-magnetize direction at both ends, the curve a is only at one end. A case is shown in which a current is passed through a conductor for applying a magnetic field in a difficult-to-magnetize direction. According to this result, it can be seen that the magnetic field generated from two conductors spaced apart and having current flowing in the same direction has no magnetic field gradient in the middle part of the conductors, and becomes a --like magnetic field. FIG. 4 compares the effect of Barkhausen noise suppression according to the present invention. The broken line in the figure is the same element shape as this example, and when there is no bias in the easy direction, the - dotted line connects both voltages Vi1c and 1d to zero potential, that is, bias is applied only from one side in the element easy direction. In this case, the solid line is the case of the present invention. The present invention makes it possible to apply a uniform magnetic field in the easy direction of the MR film, making it possible to obtain reproduction output without Barkhausen noise even with an element with a small aspect ratio (in this example, the aspect ratio is 2) that is compatible with a narrow trunk. I understand that. Other embodiments are shown in FIGS. 5 and 6. FIG. 5 shows a yoke type MR head (Embodiment 2). Figure 6 shows a convex MR head that protrudes from the recording medium surface by the track width (
Example 3). When a yoke-type MR head or a convex-type MR head is used, the head can be formed in a structure in which the electrode and the MR element are completely interlinked, and a bias in the direction of easy magnetization can be applied more efficiently. As a result, the current required for operation can be reduced.

【Effect of the invention】

According to the present invention, it is possible to provide a magnetic head that has a simple configuration, reduces Barkhausen noise, and is suitable for high-density magnetic recording.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of the present invention, FIG. 2 is a perspective view of essential parts of a magnetic head according to Embodiment 1 of the present invention, and FIG. 3 is a spatial distribution diagram of a bias magnetic field in the direction of easy magnetization according to the present invention. FIG. 4 is a magnetic field-output characteristic curve diagram, and FIGS. 5 and 6 are perspective views of essential parts of a magnetic head according to another embodiment of the present invention. Explanation of symbols 1a, 1b, 1c, 1 d--electrode, 2...M R
Element, 3... Bypass conductor part, 4a, 4b... Conductor part, 5... Sen=L2 V1n θ, Vz<0 C(L) Yojui Book: 1 Den 4L Kak (Tari 1 Sa (b) No 1 Jo no 2
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Claims (1)

[Claims] 1. In a magnetoresistive reproducing head equipped with a conductor for detecting resistance change, a conductor for applying a magnetic field in the direction of hard magnetization, and a conductor for applying a magnetic field in the direction of easy magnetization, the above-mentioned 3.
A magnetoresistive playback head that is characterized by passing current through individual conductors. 2. In a magnetoresistive read head having a conductor pattern for detecting resistance change provided at both ends of the magnetoresistive element, and a conductor pattern for applying a magnetic field in a direction of difficult magnetization provided adjacent to the magnetoresistive element via an insulating layer. , characterized in that one conductor pattern for detecting a resistance change and one conductor pattern for applying a magnetic field are connected at both ends of the magnetoresistive element, and are formed so as to go around the magnetoresistive element. A magnetoresistive reproducing head according to claim 1. 3. A constant current source having four electrode terminals, one of which has a positive potential and one of which has a negative potential, and the remaining two have a conductor layer shape connected to a zero potential. 2. The magnetoresistive reproducing head according to item 2.