JP6103645B2 - Magnetic field characteristic evaluation apparatus and magnetic field characteristic evaluation method - Google Patents

Description

  The present invention relates to a magnetic field characteristic evaluation apparatus and a magnetic field characteristic evaluation method for evaluating magnetic field characteristics of a magnetoresistive (MR) type magnetic head element, and more particularly to an MR type in a state where a parallel and vertical magnetic field is applied to the MR type magnetic head element. The present invention relates to a magnetic field characteristic evaluation apparatus and a magnetic field characteristic evaluation method for evaluating magnetic field characteristics of a magnetic head element.

  In general, an MR type magnetic head element employed in a magnetic disk apparatus is a read-only element that uses a magnetoresistive effect element whose electrical resistance value changes due to a magnetic field change on the magnetic disk, and is used for writing data on the magnetic disk. A composite magnetic head supported by a slider at the tip of a magnetic head arm is configured together with a magnetic recording (WR) element, and the magnetic recording (WR) element and the MR type magnetic head element are magnetic disks while flying over the magnetic disk at a minute interval. It is configured to perform data recording / reproduction to / from. In particular, in recent composite type magnetic heads having a minimal flying height, a slider is provided with a heating element to positively utilize the TPTP (Thermal Pole Tip Expansion) phenomenon, so that individual magnetic head elements can be used. A technology that adjusts the flying height variation and accurately controls a small flying height is employed.

  This MR type magnetic head element includes an antiferromagnetic layer made of an antiferromagnetic material having no magnetic moment between a lower shield layer and an upper shield layer facing the magnetic disk surface, and a fixed layer having a fixed magnetization direction. And an insulating layer made of an insulating material and a free layer whose magnetization direction is changed by an external magnetic field are stacked and sandwiched between hard bias layers. When a magnetic field is applied from the lower shield layer side, FIG. When the magnetization direction of the free layer is parallel to the magnetization direction of the fixed layer as shown in FIG. 5A and a magnetic field is applied from the upper shield layer side, the magnetization direction of the free layer is changed to the fixed layer as shown in FIG. The magnetization direction of each of the magnetic films is antiparallel, and data reproduction is performed by utilizing the fact that the tunnel current passing through the insulating layer changes depending on the magnetization angle of each magnetic film (resistance change). .

  A composite magnetic head equipped with a magnetic recording element (WR element), a magnetoresistive effect element (MR element), and a TFC element as a heating element constructed as described above needs to be evaluated for magnetic characteristics as a process of commercialization. As a document describing a technique for evaluating (inspecting) the magnetic characteristics of this composite magnetic head, the following Patent Document 1 is cited. In this Patent Document 1, a substantially vertical magnetic field under a specific condition is combined. Measure the output voltage of the magnetic head by applying it to the magnetic head, apply a noise stress magnetic field, then apply a substantially vertical magnetic field of a specific condition to the composite magnetic head again to measure the output voltage of the magnetic head, and finally A technique for detecting magnetic output instability failure due to external influences by comparing these output voltage differences and standard values to determine pass / fail is described.

JP 2006-302414 A

  The technique described in Patent Document 1 detects a magnetic output instability defect by applying a noise stress magnetic field after applying a vertical magnetic field, further applying a substantially vertical magnetic field, and comparing the output voltage difference with a standard value. However, in recent composite type magnetic heads, the upper and lower shield layers are provided to prevent the influence of external magnetic fields from other than the magnetic disk. The composite magnetic head has also been miniaturized, and it is difficult to accurately evaluate the characteristics of the composite magnetic head equipped with the commercialized MR magnetic head element only by evaluating the magnetic head characteristics by applying a vertical magnetic field. Therefore, it is conceivable to apply a horizontal magnetic field to the MR magnetic head element, but the magnetic coil for applying the magnetic field is close to the vicinity of the composite magnetic head. Placing Te has been difficult.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional technology, and a magnetic field characteristic evaluation apparatus and a magnetic field characteristic evaluation capable of accurately evaluating a magnetic characteristic of a composite magnetic head equipped with an MR magnetic head element. Is to provide a method.

  In order to achieve the above object, according to the first aspect of the present invention, an antiferromagnetic layer made of an antiferromagnetic material having no magnetic moment and a magnetization direction are fixed between the lower shield layer and the upper shield layer. Insulation by applying an external magnetic field to an MR type magnetic head element constructed by laminating a fixed layer, an insulating layer made of an insulating material, and a free layer whose magnetization direction is changed by an external magnetic field and sandwiched by a hard bias layer A magnetic field characteristic evaluation apparatus that evaluates characteristics of a composite magnetic head using a resistance change of a tunnel current passing through a layer, and a spindle motor that supports a magnetic disk while rotating, and a floating state on the magnetic disk A magnetic head to be supported, and a vertical U-shaped magnetic field applied to the magnetic head are formed so as to sandwich the upper and lower surfaces of the magnetic disk. Schematic comprising a coil and a parallel coil for applying a DC magnetic field in a parallel direction to a magnetic head on a magnetic disk, wherein the parallel coil has an opening for generating a magnetic field, and a slit is provided on one side. It is composed of a B-shaped coil main body and a plurality of conductive wires wound around the other three sides of the coil main body, and is configured to insert and arrange a magnetic disk between the slits. First feature.

  According to a second aspect of the present invention, in the magnetic field characteristic evaluation apparatus according to the first feature, the magnetic disk is rotated at a predetermined rotational speed so that the magnetic head is positioned on the magnetic disk, loaded onto the magnetic disk, and the parallel coils. And measuring a change in the resistance value change amount of the insulating layer of the MR type magnetic head element when the vertical AC magnetic field changes in a state where a predetermined amount of parallel DC magnetic field is applied to the magnetic head. 3. The magnetic field characteristic evaluation apparatus according to any one of the above features, wherein the magnetic head includes a heating element that controls a flying height with respect to the magnetic disk using a thermal pole chip expansion phenomenon, and the heat generation of the magnetic head. The third feature is to measure the transition of the amount of change in resistance value of the body.

  According to a fourth aspect of the present invention, an antiferromagnetic layer made of an antiferromagnetic material having no magnetic moment, a fixed layer having a fixed magnetization direction, and an insulating material are provided between the lower shield layer and the upper shield layer. The resistance of the tunnel current passing through the insulating layer by applying the external magnetic field to the MR type magnetic head element constructed by laminating the insulating layer and the free layer whose magnetization direction is changed by the external magnetic field and sandwiched by the hard bias layer A magnetic field characteristic evaluation method for a magnetic field characteristic evaluation apparatus that evaluates characteristics of a composite magnetic head using changes, a spindle motor that supports a magnetic disk while rotating, and is supported in a floating state on the magnetic disk A perpendicular coil for applying a vertical alternating magnetic field to the magnetic head, which is formed in a generally U shape so as to sandwich the magnetic head and the upper and lower surfaces of the magnetic disk A coil body having a generally rectangular shape having an opening for generating a magnetic field to apply a DC magnetic field in a parallel direction to a magnetic head on a magnetic disk, and having a slit on one side; and the coil body And a parallel coil section configured to insert and arrange the magnetic disk in the space between the slits, and the magnetic disk is rotated at a predetermined number of rotations. An MR type magnetic head element when the vertical AC magnetic field changes in a state where the magnetic head is rotated and positioned on the magnetic disk, loaded onto the magnetic disk, and a predetermined amount of parallel DC magnetic field is applied to the magnetic head by the parallel coil. It is a fourth feature that the transition of the resistance value change amount of the insulating layer is measured.

  According to a fifth aspect of the present invention, in the magnetic field characteristic evaluation method according to the fourth aspect, the magnetic head includes a heating element for controlling a flying height with respect to the magnetic disk by utilizing a thermal pole chip expansion phenomenon, A fifth feature is to measure the transition of the resistance value change amount of the heating element.

  In the magnetic field characteristic evaluation apparatus and magnetic field characteristic evaluation method according to the present invention, a parallel coil is generated from a vertical coil in a state in which a magnetic disk is inserted into a slit provided on one side and a parallel DC magnetic field is applied to an MR type magnetic head element. To evaluate the parallel magnetic field of a composite magnetic head element mounted with an MR type magnetic head element by measuring the change in the resistance value of the insulating layer of the MR type magnetic head element when the vertical AC magnetic field is changed. Can do.

The figure for demonstrating the schematic structure of the magnetic field characteristic evaluation apparatus by embodiment of this invention. The figure for demonstrating the circuit structure of the magnetic field characteristic evaluation apparatus by this embodiment. The figure for demonstrating the parallel coil by this embodiment. The figure for demonstrating the silicon steel plate of the parallel coil by this embodiment. The figure for demonstrating the vertical coil by this embodiment. The figure for demonstrating the silicon steel plate of the vertical coil by this embodiment. FIG. 3 is a diagram for explaining an MR type magnetic head element which is a target of the embodiment. The figure for demonstrating the subject of this embodiment. The figure which shows the resistance value change of MR type magnetic head element used as the object of this embodiment.

Hereinafter, an embodiment of a magnetic field characteristic evaluation apparatus to which a magnetic field characteristic evaluation method according to the present invention is applied will be described in detail with reference to the drawings.
[Explanation of issue]
First, details of the problem to be solved by the present invention will be described. As described above, the upper shield and the lower shield of the MR type magnetic head element are provided to prevent the disturbance magnetic field from other than the magnetic disk from affecting the antiferromagnetic layer, the fixed layer, the insulating layer, and the free layer. However, since each layer has become thinner and smaller with the miniaturization of the composite magnetic head, the MR type magnetic head element shown in FIG. When a parallel external magnetic field is applied, depending on the magnetic domain structure of the upper and lower shield layers, as shown in FIG. 6B, the magnetization direction can be easily reversed to the opposite direction, and the magnetization direction of the free layer can be changed stably. It becomes difficult to read magnetic information.

[Constitution]
As shown in FIG. 1, the mechanical configuration of the magnetic field characteristic evaluation apparatus for a composite magnetic head equipped with the MR magnetic head element according to the present embodiment includes a spindle motor 19 that supports the magnetic disk 10 while rotating, and the magnetic disk. A magnetic head 11 that is supported in a floating state on 10 (not shown in the shadow of a coil to be described later), and an XY for moving the magnetic head 11 in an XY direction perpendicular to the surface of the magnetic disk 10 The magnetic head is formed in a substantially U shape so as to sandwich the stage 21, the Z stage 22 for moving the magnetic head 11 in the vertical Z direction with respect to the surface of the magnetic disk 10, and the upper and lower surfaces of the magnetic disk 10. 11 to apply a vertical AC (alternating current) magnetic field to the vertical coil 60 and a DC (parallel to the magnetic head 11 on the magnetic disk 10). And a parallel coil 50 for applying a fluid) field.

  As shown in the perspective view of FIG. 4A (a) and FIG. 4B, the vertical coil 60 is provided with a coil body 61a having a substantially square shape having an opening 61b and an opening 61b of the coil main body 61a. And three conducting wires 62 wound around the three sides of the coil main body 61a. An AC (alternating current) magnetic field is generated between the openings 61b of the coil body 61a. 4A to 4D are a top view, a left side view, and a right side view with respect to the perspective view of the vertical coil 60. FIG.

  The parallel coil 50, which is a feature of the present embodiment, has a substantially square-shaped coil main body having an opening 51b and a slit 51c on one side, as shown in the perspective view of FIG. 3A and FIG. 3B. 51a and three conducting wires 52 wound around the other three sides of the coil main body 51a, and the magnetic disk 10 is inserted and arranged in the space between the slits 51c, thereby opening the coil main body 51a. A DC (direct current) magnetic field is generated between the parts 51 b and applied to the magnetic head 11. 3A to 3D are a top view, a left side view, and a right side view with respect to the perspective view of the parallel coil 50. FIG.

  This horizontal coil 50 has a width of 60 mm, a height of 60 mm, a thickness of 10 mm, a width of a slit 51 c of 2.5 mm, a depth of 40 mm, and a width of 40 mm between the openings 51 b of the silicon steel plate 51. Is set to 12 mm, and the width of the conductive wire 52 covering the coil main body 51a is set to 7 mm (24 mm in outer diameter), a horizontal magnetic field of 500 [Oe] at maximum can be generated. Note that the material of the horizontal and vertical coils is not limited to that described above.

  As shown in FIG. 2, the circuit configuration of the magnetic field characteristic evaluation apparatus configured as described above is a stage for driving an XYX stage 21 and a Z stage 22 on which an HGA (Head Gimbal Assembly) jig for supporting the magnetic head 11 is mounted. Motor driver 201, spindle motor driver 206 for driving the spindle motor 19, MR resistance measuring device 203 for measuring the resistance value of the MR type magnetic head element of the magnetic head 11, and resistance value of the TFC element of the magnetic head 11 A TFC resistance measuring device 204 for measuring the resistance, a DVH measuring amplifier 202 for measuring a change in the resistance value of the MR type magnetic head element of the magnetic head 11, an AC magnetic field generated in the opening 61b of the vertical coil 60, and a parallel coil Coil that is driven to generate a DC magnetic field in 50 openings 51b A driver 205, a stage motor driver 201, a spindle motor driver 206, an MR resistance measuring device 203, a spindle motor driver 206, a TFC resistance measuring device 204, a DVH measuring amplifier 202, and a control circuit 200 for controlling the coil driver 205 are provided. .

[Operation]
In the magnetic field characteristic evaluation apparatus configured as described above, the control circuit 200 rotates the spindle motor 19 at a predetermined number of rotations under the control of the spindle motor driver 206 so that the magnetic head 11 is positioned on the magnetic disk 10 and the stage motor driver. The magnetic head 11 is loaded onto the magnetic disk 10 by being moved in the XYZ directions by the XY stage 21 and the Z stage 22 under the control of 201, and a predetermined amount of DC magnetic field is applied to the magnetic head 11 by the parallel coil 50 under the control of the coil driver 205. And the vertical coil 60 is applied to the magnetic head 11 while changing the vertical AC magnetic field, and the change in the resistance value of the MR magnetic head element by the DVH measuring amplifier 202 when the vertical AC magnetic field changes, The change in resistance value change is, for example, perpendicular to the X axis. AC magnetic field by 60, as shown in FIG. 7 plots the change in resistance of the MR magnetic head element for AC magnetic field to the Y axis operates to measure and evaluate.

  Particularly in the present embodiment, the coil driver 205 applies a predetermined parallel DC magnetic field to the opening 51a of the parallel coil 50, thereby amplifying or canceling the influence of the parallel magnetic field that affects the MR type magnetic head element. It is possible to evaluate whether or not the magnetization directions of the upper and lower shield layers are reversed.

10 magnetic disk, 11 magnetic head, 19 spindle motor,
21 XY stage, 22 Z stage, 50 vertical coil,
51a coil body part, 51b opening part, 51c slit part, 52 conducting wire,
60 vertical coil, 61a coil body, 61b opening, 62 conductor,
200 control circuit, 201 stage motor driver,
202 DVH measuring amplifier, 203 MR resistance measuring instrument,
204 TFC resistance measuring device, 205 coil driver,
206 Spindle motor driver

Claims (5)

Between the lower shield layer and the upper shield layer, an antiferromagnetic layer made of an antiferromagnetic material having no magnetic moment, a fixed layer having a fixed magnetization direction, an insulating layer made of an insulating material, and a magnetization direction being external Combined with a free layer that changes depending on the magnetic field, a composite type magnetic field utilizing the resistance change of the tunnel current passing through the insulating layer due to the application of an external magnetic field to an MR type magnetic head element configured to be sandwiched between hard bias layers A magnetic field characteristic evaluation apparatus for evaluating the characteristics of a head,
A spindle motor that supports the magnetic disk while rotating, a magnetic head supported in a floating state on the magnetic disk, and a substantially U-shape that sandwiches the upper and lower surfaces of the magnetic disk and is perpendicular to the magnetic head A vertical coil for applying the alternating magnetic field and a parallel coil for applying a parallel direct current magnetic field to the magnetic head on the magnetic disk, the parallel coil having an opening for generating a magnetic field, It is composed of a generally rectangular-shaped coil main body provided with a slit on one side and a plurality of conductive wires wound on the other three sides of the coil main body, and a magnetic disk is inserted and disposed in the space between the slits. A magnetic field characteristic evaluation apparatus configured as described above.   In the state where the magnetic disk is rotated at a predetermined rotational speed, the magnetic head is positioned on the magnetic disk, loaded onto the magnetic disk, and a predetermined amount of parallel DC magnetic field is applied to the magnetic head by the parallel coil. 2. The magnetic field characteristic evaluation apparatus according to claim 1, wherein a transition of a resistance value change amount of the insulating layer of the MR type magnetic head element at the time of change is measured.   The magnetic head includes a heating element that controls a flying height with respect to a magnetic disk by utilizing a thermal pole tip expansion phenomenon, and measures a change in a resistance change amount of the heating element of the magnetic head. 2. Magnetic field characteristic evaluation apparatus according to 2. Between the lower shield layer and the upper shield layer, an antiferromagnetic layer made of an antiferromagnetic material having no magnetic moment, a fixed layer having a fixed magnetization direction, an insulating layer made of an insulating material, and a magnetization direction being external Combined with a free layer that changes depending on the magnetic field, a composite type magnetic field utilizing the resistance change of the tunnel current passing through the insulating layer due to the application of an external magnetic field to an MR type magnetic head element configured to be sandwiched between hard bias layers A magnetic field characteristic evaluation method for a magnetic field characteristic evaluation apparatus for evaluating the characteristics of a head,
A spindle motor that supports the magnetic disk while rotating, a magnetic head supported in a floating state on the magnetic disk, and a substantially U-shape that sandwiches the upper and lower surfaces of the magnetic disk and is perpendicular to the magnetic head A vertical coil for applying an alternating magnetic field, and an opening for generating a magnetic field for applying a direct magnetic field in parallel to a magnetic head on a magnetic disk, with a slit portion on one side. A coil body portion having a shape and a plurality of conductive wires wound around the other three sides of the coil body portion, and a parallel coil portion configured to insert and arrange a magnetic disk between the slits. The magnetic disk is rotated at a predetermined rotational speed, the magnetic head is positioned on the magnetic disk, loaded onto the magnetic disk, and a predetermined amount of flatness is applied to the magnetic head by the parallel coil. In a state of applying a DC magnetic field, the magnetic field characteristic evaluation method characterized by measuring the changes of the resistance change amount in the insulating layer of the MR type magnetic head element during the vertical alternating magnetic field changes. The magnetic head includes a heating element that controls a flying height with respect to a magnetic disk by utilizing a thermal pole tip expansion phenomenon, and measures a change in a resistance change amount of the heating element of the magnetic head. 4. The magnetic field characteristic evaluation method according to 4.

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