JP3194838B2 - Magnetic field measuring method and magnetic field measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field measuring method and a magnetic field measuring apparatus capable of detecting the intensity of a magnetic field generated from a magnetic head and other elements for converting a current into a magnetic field with high accuracy.

[0002]

2. Description of the Related Art It has been extremely difficult to detect the intensity of a magnetic field generated from a minute element such as a magnetic head. On the other hand, recently, a magneto-optical recording device of the magnetic field modulation recording type has been commercialized, and it is necessary to measure the intensity of a magnetic field generated by a magnetic head used in this device.
In addition, other types of recording devices using magnetism are also required to have a high precision in the recording operation, and it is required to measure the intensity of the generated magnetic field and perform product inspection and the like with high accuracy. Conventionally, as a means for measuring the intensity of a magnetic field generated from a minute element such as a magnetic head, a measurement method using an I-turn coil and a measurement method using an electron beam have been reported.

[0003]

However, the measurement of the magnetic field strength using the I-turn coil has the disadvantage that the detection sensitivity is low and the spatial resolution, particularly the resolution in the spacing direction, cannot be sufficiently secured. In addition, in the measurement using an electron beam, the equipment used for the measurement is large-scale, which not only increases the equipment cost, but also takes time for the measurement, and furthermore, the position of the magnetic head or the like to be measured is aligned with the electron beam. There is a very difficult disadvantage.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and can measure a magnetic field intensity emitted from a magnetic head and other minute elements with high accuracy, and can simplify the structure of the entire apparatus. It is an object to provide a method and a magnetic field measuring device.

[0005]

According to the magnetic field measuring method of the present invention , a non-magnetic material is formed on a plane of a magnetic film having uniaxial anisotropy.
The magnetic head is installed with a spacer consisting of
The magnetic head applies a magnetic field to be measured in the direction of the hard axis of the magnetic film, irradiates the magnetic film to which the magnetic field is applied with detection light of linear polarization, and rotates the polarization plane of the detection light passing through the magnetic film. The method is characterized in that the intensity of the magnetic field is measured by detecting an angle. The magnetic film and the magnetic
The distance between the magnetic heads is used for the recording operation by the magnetic head.
The amount of spacing with the recording medium when
Wear. Also, the side of the magnetic film on which the detection light is irradiated
A reflective film that reflects the detection light is installed on the surface opposite to the surface
And the linearly polarized light is applied to the magnetic film to which a magnetic field is applied.
Irradiates detection light, and detects the light reflected by the reflection film.
By detecting the rotation angle of the polarization plane of the emitted light,
The strength can be measured. Alternatively, the magnetic film
Reflects the detection light, and is provided with a magnetic field.
Irradiating the linearly polarized detection light to the magnetic film,
Rotation angle of the plane of polarization of the detection light reflected by the conductive film
By detecting, the strength of the magnetic field can be measured.
Wear.

A magnetic field measuring apparatus according to the present invention includes a magnetic film having uniaxial anisotropy , a magnetic head serving as a magnetic field generating member for applying a magnetic field to the magnetic film, the magnetic film and the magnetic head.
A spacer made of a non-magnetic material placed between
Serial has a light emitting portion where the magnetic field of the magnetic film is irradiated with detection light of the linearly polarized light to the portion provided, and a detector for detecting the rotation angle of the polarization plane of the detection light passing through the magnetic layer, to the detection unit The strength of the magnetic field applied to the magnetic film from the magnetic head is measured based on the rotation angle detected by the magnetic head . Note that the distance between the magnetic film and the magnetic head is
The recording medium is separated when the magnetic head is used for a recording operation.
It can be made the amount of spacing with the body.

[0007] In the above, the direction of the measured magnetic field applied to said magnetic <br/> film from the magnetic head is preferably a hard magnetization axis direction of the magnetic layer.

Further , the detection light of the magnetic film is irradiated.
Reflects the detection light installed on the side opposite to the side
Reflective film. Alternatively, the magnetic film
Reflects the detection light. The rotation angle detected by the detection unit is processed by the signal processing unit, and the intensity of the magnetic field applied to the magnetic film is displayed on the display unit.

In the above, the magnetic head comprises an element for converting a current into a magnetic field.

[0010] In this case, the output corresponding to the rotation angle detected by the detection unit is processed by the signal processing unit, the magnetic
The relationship between the current applied to the magnetic head and the intensity of the magnetic field applied to the magnetic film can be displayed on the display unit.

[0011]

According to the magnetic field measuring method and the magnetic field measuring apparatus, when a linearly polarized detection light is applied to the magnetic film, the rotation angle of the polarization plane of the light passing through the magnetic film changes according to the intensity of magnetization of the magnetic film. I use. When the detection light of the linearly polarized light passes through the magnetic film, the rotation angle of the polarization plane rotates with respect to the polarization plane of the incident light in proportion to the intensity of the magnetization due to the Faraday effect. The rotation angle of the polarization plane of the transmitted light with respect to the incident light is represented by θF (Faraday rotation angle). When the linearly polarized detection light is reflected from the magnetic film, the rotation angle of the polarization plane rotates with respect to the polarization plane of the incident light in proportion to the intensity of magnetization due to the Kerr effect. The rotation angle of the polarization plane of the reflected light with respect to the incident light is θk
(Kerr rotation angle).

In the above means, a magnetic field to be measured, that is, a magnetic field from the magnetic head to be measured is applied to the magnetic film to magnetize the magnetic film, and linearly polarized detection light is applied to the magnetic film. Then, the Faraday rotation angle θF or the Kerr rotation angle θk is detected with respect to light transmitted through the magnetic film or light reflected from the magnetic film. This makes it possible to measure the intensity of the magnetization of the magnetic film, that is, the intensity of the magnetic field applied to the magnetic film.

Here, a magnetic film having uniaxial anisotropy is used. When a magnetic field to be measured is applied in the easy axis direction of the magnetic film, the magnetic film is magnetized by a relatively small magnetic field. However, in this case, a coercive force is generated in the magnetic film, a hysteresis characteristic is generated between a magnetic field applied from the outside and the magnetization of the magnetic film, and a residual magnetization is generated by the coercive force of the magnetic film.

On the other hand, a preferred embodiment of the present invention is characterized in that the direction of the magnetic field to be measured is the direction of the hard axis of the magnetic film. When the magnetic field H to be measured is applied in the direction of the hard axis of the magnetic film, when the applied magnetic field H is equal to or less than the anisotropic magnetic field Hk of the magnetic film, the magnetization M of the magnetic film is proportional to the intensity of the applied magnetic field H. . When the magnetic field H is equal to or higher than Hk, the magnetic film becomes the saturation magnetization Ms, and the intensity of the magnetization becomes constant. When the detection light of linearly polarized light is given to the magnetic film, the rotation angle θF of the polarization plane of the transmitted light or the rotation angle θk of the polarization plane of the reflected light is proportional to the magnetization intensity of the magnetic film. Therefore, if the magnetic field applied to the magnetic film is equal to or smaller than Hk, the strength of the magnetic field H is proportional to the rotation angle θF or θk.

In the above means, the strength of the magnetic field H applied to the magnetic film can be detected by detecting the rotation angle θF or θk by the detection unit. By processing the detected output of the rotation angle by the signal processing unit and displaying the processed signal, the intensity of the magnetic field from the magnetic head as the object to be measured can be detected with high accuracy.

Further, the magnetic head for applying a magnetic field to the magnetic film.
If de is an element for converting a current to the magnetic field, the magnetic
The magnetic field H applied to the magnetic film changes according to the current value applied to the head . Therefore, the rotation angle θF or θk of the polarization plane of the detection light that has passed through the magnetic film changes according to the current applied to the magnetic head . The signal processing unit converts the intensity of the magnetization M of the magnetic film based on the rotation angle θF or θk, and the current value Ii applied to the magnetic head in the display unit and the intensity of the magnetization M of the magnetic film. (The intensity of the applied magnetic field H) can be displayed in a graph or the like.

Here, a reference magnetic field generator such as an electromagnet or a permanent magnet is used, which generates a magnetic field of a constant strength and whose strength of the generated magnetic field is known in advance by measurement using a Hall element or the like. The reference magnetic field is applied to the magnetic film, and the relationship between the strength of the magnetic field H applied to the magnetic film and the rotation angle θF or θk, that is, the magnetization M of the magnetic film is determined. Then, a magnetic field H is applied to the magnetic film from a magnetic head (element for converting a current into a magnetic field) to be measured, and the rotation angle θF or θk at that time is measured. This measured value is compared with H and θF, θk or H when an electromagnet or the like having a constant magnetic field is used.
From the relationship between M and M, it is possible to know the relationship between the current value Ii given to the magnetic head or the like and the intensity of the magnetic field H generated from the magnetic head or the like. The signal processing unit performs this calculation and displays the relationship between the current value Ii given to the magnetic head or the like and the intensity of the magnetic field H generated from the magnetic head or the like on the display unit. It becomes possible to measure the relationship between the supply current and the generated magnetic field of the element.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a magnetic field measuring device according to the present invention. Hereinafter, the structure of the magnetic field measuring apparatus and a magnetic field measuring method using the magnetic field measuring apparatus will be described. FIG.
In the example shown in FIG. 1, an element for converting a current to a magnetic field, that is, a magnetic head
Are used, and the object to be measured in the magnetic field measurement is the magnetic head 1.

The magnetic head 1 shown in FIG. 1 is of a vertical magnetic field type which applies a magnetic field in a perpendicular direction to a magneto-optical disk in a magneto-optical recording device, for example. As shown in FIG. 2, the C-type side cores 1 are provided on both sides of an I-type center core 1a.
b and 1b are joined to form a pair of magnetic gaps G. The coil 1c is wound around the I-shaped core 1a. In a recording operation using a recording medium such as a magneto-optical disk, a magnetic field is applied from the magnetic head 1 to the recording medium in the vertical direction (Z direction). In the magnetic field measuring apparatus, a magnetic film 11 is formed on a surface of a transparent substrate 10 such as a glass substrate on the side of a magnetic head. The thickness of the magnetic film 11 is about several hundred angstroms. The magnetic film 11 is made of, for example, Co-
It is an in-plane magnetized film such as a Ni-Cr alloy film. That is, the magnetic film 11 has uniaxial anisotropy in the plane direction (X direction), and the plane direction (X direction) is the easy axis direction.
Therefore, the direction of the perpendicular magnetic field (Z
Direction), the magnetic film 11 has a hard axis direction.

The magnetic film 11 is as thin as several hundred angstroms. In the case of a thin magnetic film 11, the detection light passes through the magnetic film 11, and the polarization plane of the transmitted detection light rotates with respect to the polarization plane of the incident light due to the Faraday effect. The rotation angle of the polarization plane to be detected is indicated by θF. Magnetic film 11
Is to detect transmitted light to the magnetic film 1
A reflective film 12 of aluminum (Al) or the like is laminated on the lower surface of the substrate 1. This reflection film 12 also functions as a protective film for the magnetic film 11. The thickness of the reflective film 12 is several hundred angstroms.

As shown in FIG. 1, a magnetic head 1, which is a magnetic field generating member (measured object), is fixed on a stage 15 capable of changing its position in XYZ three-dimensional directions.
The reflective film 12 is provided in close contact with the magnetic head 1 via a spacer 14 made of a nonmagnetic material. Spacer 1
By making the thickness of the magnetic head 1 correspond to the actual spacing with the recording medium when the magnetic head 1 is mounted on a magneto-optical recording device or the like, the thickness of the magnetic head 1 when the magnetic head 1 is used for a recording operation is determined. It is possible to measure the magnetic field H applied to the recording medium. Further, when it is not necessary to measure the intensity of the magnetic field H via spacing, the spacer 14 may be omitted. The light emitting section 20 is provided with a semiconductor laser 21 as a light emitting element that generates linearly polarized light.
The semiconductor laser 21 has a semiconductor chip sealed in a case. The divergent light emitted from the semiconductor laser 21 is converted into parallel light by the collimating lens 22,
After passing through the beam splitter 23, the light is focused by the condenser lens 24, passes through the transparent substrate 10, and is irradiated on the magnetic film 11 as detection light.

The detection unit 30 reflects light from the reflection film 12,
Further, it has a converging lens 31 for converging the return light of the detection light reflected in the right angle direction by the beam splitter 23. A polarization beam splitter 32 that splits the return light into a P-wave component and an S-wave component is provided on the path of the focused light. The P-wave component and the S-wave component of the return light are received by pin photodiodes 33 and 34, which are light receiving elements, respectively. The difference output device 35 obtains a detection current I0 which is a difference between the detection current photoelectrically converted by the pin photodiode 33 and the detection current photoelectrically converted by the pin photodiode 34. This detection current I0 is the difference between the photoelectric conversion output of the P-wave component and the photoelectric conversion output of the S-wave component of the return light. It becomes proportional to the rotation angle θF of the polarization plane of the transmitted light of the magnetic film 11. Further, a current value Ii applied to the coil 1c is detected from a current supply unit 36 provided in the magnetic head 1 for applying an electric current to the coil 1c. The detected current I0 and the current value Ii given to the coil 1c are given to the signal processing unit 41. In the signal processing unit 41, the strength of the magnetization M of the magnetic film 11 (the strength of the magnetic field H applied to the magnetic film 11) based on the detected current I0.
Is detected.

Next, a method for measuring a magnetic field using the magnetic field measuring apparatus having the above structure will be described. XYZ stage 15
A magnetic head 1 as a magnetic field generating member (measured member)
Is fixed, and a spacer 14 is placed thereon, and further a transparent substrate 10 on which a magnetic film 11 and a reflective film 12 are laminated is placed in close contact therewith. Stage 15 is XY-
By moving in the Z direction, the portion of the magnetic gap G of the magnetic head 1 is made to coincide with the irradiation area of the detection light from the condenser lens 24. Then, the linearly polarized detection light emitted from the semiconductor laser 21 is focused and irradiated on the magnetic film 11. Then, a magnetic field H is applied from the magnetic head 1 to the magnetic film 11, and the return light transmitted through the magnetic film 11 and reflected by the reflection film 12 is received by the pin photodiodes 33 and 34.

In this embodiment, the detected magnetic field applied to the magnetic film 11 from the magnetic head 1 as a magnetic field generating member is a vertical magnetic field (Z-direction magnetic field), whereas the magnetic film 11 is an in-plane magnetized film. , Z directions are hard magnetization axes. In this case, as shown in FIG. 3, when the intensity of the magnetic field H applied to the magnetic film 11 is equal to or less than the anisotropic magnetic field Hk of the magnetic film, the intensity of the magnetic field H applied to the magnetic film 11 becomes Magnetic film 1
1 is proportional to the magnitude of the magnetization M. When the magnetic field H becomes equal to or higher than Hk, the magnetic film 11 becomes the saturation magnetization Ms and has a constant value. Therefore, when the magnetic field H is equal to or less than Hk, the magnitude of the perpendicular magnetic field H from the magnetic head 1 and the magnetization M
Is proportional to the size of The magnitude of the magnetization M of the magnetic film 11 is proportional to the rotation angle (Faraday rotation angle) θF of the plane of polarization of linearly polarized light transmitted through the magnetization film 11, and the rotation angle θF
Can be obtained as the detection current I0. Therefore, the signal processing unit 41 detects the detection current I0,
It is possible to recognize the magnitude of the magnetization M of the magnetic film 11 and the magnitude of the magnetic field H from the magnetic head 1 in proportion thereto.

As the signal processing unit 41, a unit capable of digital operation such as a microcomputer is preferably used.
When the signal processing unit 41 is a digital operation unit, the detected current I0 and the current value Ii supplied to the coil 1c are analog /
The operation is performed after being converted into a digital value by the digital conversion unit. Alternatively, the current values I0 and Ii are converted into a voltage value by a current / voltage conversion unit, further converted into a digital value, and then digitally operated. Alternatively, the detection currents of the pin photodiodes 33 and 34 are converted into a voltage value by a current / voltage conversion unit, and a difference output unit 35 outputs a difference between the two detection voltages. Digital operation. These calculation results are displayed by the display unit 43 having a display. Alternatively, the detected currents I0 and Ii may be processed by an analog circuit in the signal processing unit 41, and this may be directly displayed on the display unit 43 such as a synchroscope.

Processing Method by Signal Processing Unit 41 and Display Unit 4
As a display method at 3, the current value Ii applied to the coil 1c of the magnetic head 1 is simply increased continuously based on a predetermined proportional straight line, and the detected current I0 at this time is displayed on the display unit. It is possible to display a level on the screen 43 or to display a numerical value on the display unit 43. Thus, it is possible to know the tendency of the magnetization M of the magnetic film 11 to increase (the tendency of the generated magnetic field H to increase) with respect to the increase in the current value Ii given to the coil 1c.

Since the response of the magnetization M of the magnetic film 11 to the magnetic field H applied to the magnetic film 11 is very fast, an alternating current is applied to the coil 1c and the magnetic head 1 generates the alternating magnetic field H. Then, the detection current I0 can be changed with high responsiveness. Therefore, if the current I0 detected by the alternating current is subjected to digital processing or analog processing by the signal processing section 41 and displayed on the screen of the display section 43 (in the case of analog processing, a synchroscopic screen or the like), the AC magnetic field H It is possible to know the intensity change, and it is also possible to measure the intensity (amplitude) of the AC magnetic field.
Further, by using a reference magnetic field whose magnetic field strength is known in advance, it is possible to know the relationship between the current value Ii supplied to the coil 1c and the generated magnetic field H of the magnetic head 1.

As the reference magnetic field generator in this case, an electromagnet or a permanent magnet which generates a magnetic field of a constant strength and whose magnitude is known in advance by measurement using a Hall element or the like can be used. used. This reference magnetic field generator is installed in place of the magnetic head 1 shown in FIG. At this time, it is preferable to apply a reference magnetic field having a plurality of levels of intensity obtained by changing the magnetic field intensity in proportion to the magnetic film 11. This reference magnetic field is applied to the magnetic film 11 to obtain a detection current I0. From the reference magnetic field H of the reference magnetic field generator known in advance and the detected current I0, FIG.
As shown in FIG. 7, a relationship diagram between the magnitude of the magnetic field H applied to the magnetic film 11 and the detected current I0 is obtained.

The relationship between the magnitude of the magnetic field H and the detected current I0 ((a) in FIG. 5) is stored in the storage section 42 as a digital value. Next, a magnetic head 1 as an object to be measured (a magnetic field generating member) is installed as shown in FIG.
The current value Ii given to the coil 1c is linearly increased, and a change in the detected current I0 at that time is detected. By performing digital arithmetic processing by the signal processing unit 41, FIG.
As shown in (b), the relationship between the supply current value Ii to the coil 1c and the detection current I0 based on the rotation angle θF is obtained.
Here, the relationship between the detected current I0 and the magnetic field H shown in FIG. Magnetic head 1
By applying the magnetic field H in FIG. 5 (a) to the detection current I0 in FIG. 5 (b) detected by setting the above, the relationship between the current Ii and the magnetic field H shown in FIG. be able to.

In the above-described arithmetic processing, the detection current I0 is obtained as a function of the magnetic field H, for example, in a measurement using a reference magnetic field generator. Next, when the detected current I0 is obtained by installing the magnetic head 1 to be measured, I0 is obtained as a function of Ii. By eliminating I0 from both functions, the coil 1c
Between the current value Ii and the magnetic field H can be calculated. This is displayed on the screen of the display unit 43 as shown in FIG. As shown in FIG. 5C, the current value Ii given to the coil 1c
By knowing the relationship between the magnetic head and the magnetic field H generated from the magnetic head 1, the current-magnetic field characteristics of the magnetic head itself can be known, and the magnetic characteristics of the magnetic head can be evaluated.

The use of the reference magnetic field generator not only makes it possible to know the change of the generated magnetic field H with respect to the linear change of the current value Ii, as shown in FIG. It is also possible to know the relationship between the AC current Ii and the change in the generated magnetic field H when the AC current Ii is applied. Also, the saturation magnetic field Ms of the magnetic film 11 is
When the saturation magnetic field is larger than the saturation magnetic field of the core of the magnetic head 1, it is possible to know the saturation magnetic field Hs generated from the magnetic head 1 with respect to the current value Ii to the coil as shown in FIG. By knowing the change in the generated magnetic field H with respect to the current value Ii to the coil and the saturation magnetic field Hs, the characteristics of the magnetic head can be sufficiently grasped.

In this magnetic field measuring apparatus and measuring method, the spatial resolution of the magnetic field H that can be detected depends on the accuracy of the spot diameter of the detection light focused by the condenser lens 24 and applied to the magnetic film 11 and the thickness of the spacer 14. Is determined by The spot size is proportional to the emission wavelength of the semiconductor laser 21 and inversely proportional to the numerical aperture NA of the condenser lens 24.
It is possible to make it about μm. Since the thickness of the spacer 14 is several μm, the magnetic field H can be detected with a resolution in a space of about μm cubic.

Next, in order to detect the in-plane magnetic field component (magnetic field component in the X direction) of the magnetic head or other element as the magnetic field generating member, contrary to the one shown in FIG.
A perpendicular magnetization film is used as 1 and the magnetic field measurement direction X
The direction is defined as the hard axis. As this perpendicular magnetization film,
A Gd-Co-based magnetic film, a Tb-Fe-Co-based magnetic film, or the like is used. When the magnetic film 11 reflects the detection light, the reflection film 12 is unnecessary, and the rotation angle of the polarization plane is detected as the Kerr rotation angle θk. However, the detection current I0 can be obtained from the difference between the output values of the pin photodiodes 33 and 34, as in FIG.

As described above, with the magnetic field measuring apparatus and the magnetic field measuring method of the present invention, it is possible to measure the intensity of the magnetic field emitted from a minute element such as a magnetic head with high accuracy. Further, it is possible to configure a current converter using the magnetic field measuring device. The current converter includes an element such as a magnetic head 1 for converting a current into a magnetic field, and a uniaxially anisotropic magnetic film 11 to which a magnetic field from the element is applied.
A light emitting unit 20 that applies linearly polarized detection light to the magnetic film 11; and a rotation angle (θF or θk) of the polarization plane of the light transmitted through the magnetic film 11 or reflected from the magnetic film 11 with respect to the polarization plane of the incident light. ) And the detected current I0 according to the rotation angle.
And a detection unit 30 that obtains

In this current converter, when a predetermined current value Ii is applied to the coil of the magnetic field generating element 1 such as the magnetic head 1, a detection current I0 related to the current value Ii is obtained. The relationship between Ii and I0 depends on the magnetic characteristics of the magnetic field generating element such as the magnetic head 1 and the magnetization characteristics of the magnetic film 11. It is also possible to use a converter that obtains a relationship between the voltages Vi and V0 proportional to the current value from the currents Ii and I0. In this converter, if Ii is an input signal and I0 is an output signal, it can be used as a noise cut filter. Or a high-frequency signal conversion device taking into account the impedance of a magnetic field generating element such as the magnetic head 1,
Alternatively, it can be used as a noise filter for high frequency signals.

[0036]

As described above, in the magnetic field measuring method and the magnetic field measuring apparatus according to the present invention, it is possible to detect a change in the intensity of a magnetic field emitted from a minute element such as a magnetic head as a highly accurate electric signal. is there. In particular, by setting the direction of the hard axis of the magnetic film to the direction of the magnetic field to be measured, the intensity of the magnetic field applied to the magnetic film and the output based on the rotation angle of the polarization plane can be made to have a proportional relationship.

By providing the signal processing section and the display section, not only can the strength of the magnetic field applied to the magnetic film and the magnetization state of the magnetic film be displayed, but also the current applied to the magnetic field generating member and the magnetic field generated by the magnetic field generating member can be displayed. It is possible to display the relationship with the magnitude of the magnetic field applied to the film.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing a magnetic field measurement method according to the present invention;

FIG. 2 is an enlarged front view showing a relationship between a magnetic head as a magnetic field generating member and a magnetic film;

FIG. 3 is a diagram showing the relationship between the magnetic field applied to the magnetic film and the magnetization of the magnetic film;

FIG. 4 is a diagram showing a relationship between a current applied to a magnetic head as a magnetic field generating member and a magnetic field applied to a magnetic film;

5 (a), (b) and (c) are explanatory diagrams of a measurement diagram displayed on a display unit,

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnetic field generating member (magnetic head) 10 transparent substrate 11 magnetic film 12 reflective film 20 light emitting unit 30 detecting unit 35 difference output unit 41 signal processing unit 43 display unit

Continuation of front page (56) References JP-A-62-188982 (JP, A) JP-A-5-312928 (JP, A) JP-A-5-119130 (JP, A) JP-A-6-66904 (JP) JP-A-5-100001 (JP, A) JP-A-2-189482 (JP, A) JP-A-61-286763 (JP, A) JP-A-60-223043 (JP, A) JP-A-60-223043 59-215043 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 33/00-33/18

Claims (12)

(57) [Claims] 1. A magnetic film having uniaxial anisotropy on a film plane.
A magnetic head is interposed between spacers made of non-magnetic material.
A magnetic field to be measured is provided from the magnetic head in the direction of the hard axis of the magnetic film to be measured, and the magnetic film to which the magnetic field is applied is irradiated with linearly polarized detection light, and the polarization of the detection light having passed through the magnetic film is applied. A magnetic field measuring method, wherein the strength of the magnetic field is measured by detecting a rotation angle of a surface. 2. The distance between the magnetic film and the magnetic head
A recording medium when the magnetic head is used for a recording operation.
The magnetic field measurement according to claim 1, which is a spacing amount with the body.
Method. 3. The side of the magnetic film to which the detection light is irradiated.
A reflective film that reflects the detection light is installed on the surface opposite to the surface
And the linearly polarized light is applied to the magnetic film to which a magnetic field is applied.
Irradiates detection light, and detects the light reflected by the reflection film.
By detecting the rotation angle of the polarization plane of the emitted light,
The method for measuring a magnetic field according to claim 1, wherein the intensity is measured . 4. The method according to claim 1, wherein the magnetic film reflects the detection light.
And the linear bias is applied to the magnetic film to which a magnetic field is applied.
Before irradiating light detection light, and reflected by the magnetic film
The magnetic field is detected by detecting the rotation angle of the polarization plane of the detection light.
Magnetic field measurement according to claim 1 or 2, wherein the field strength is measured.
Method. 5. A magnetic film having uniaxial anisotropy , a magnetic head serving as a magnetic field generating member for applying a magnetic field to the magnetic film,
From a non-magnetic material placed between the conductive film and the magnetic head
Includes a spacer made, the light-emitting portion where the magnetic field of the magnetic film is irradiated with detection light of the linearly polarized light to the portion provided, and a detector for detecting the rotation angle of the polarization plane of the passed through the magnetic layer said detection light, The magnetic angle is determined by the rotation angle detected by the detection unit.
A magnetic field measuring apparatus for measuring the intensity of a magnetic field applied from a magnetic head to a magnetic film. 6. The distance between the magnetic film and the magnetic head is
A recording medium when the magnetic head is used for a recording operation;
The thickness of the spacer is set so that the spacing amount is
The magnetic field measuring apparatus according to claim 5, wherein the magnetic field measuring apparatus is fixed. 7. A direction of the measured magnetic field applied to the magnetic layer from the magnetic head, the magnetic field measuring apparatus according to claim 5 or 6 which is the direction of hard magnetization of the magnetic film. 8. A side of the magnetic film to be irradiated with the detection light.
A reflection surface for reflecting the detection light installed on the surface opposite to the surface
The magnetic field according to any one of claims 5 to 7, further comprising a projection film.
measuring device. 9. The method according to claim 1, wherein the magnetic film reflects the detection light.
The magnetic field measuring device according to claim 5, wherein
Place. 10. A rotation angle detected by the detection unit is processed by the signal processing unit, the serial to any one of claims 5 strength of the magnetic field applied to the magnetic film is displayed on the display section 9
On-board magnetic field measurement device. 11. The device according to claim 5 , wherein said magnetic head is an element for converting a current into a magnetic field .
Magnetic field measurement device. 12. An output corresponding to the rotation angle detected by the detection unit is processed by a signal processing unit, and a relationship between a current applied to the magnetic head and an intensity of a magnetic field applied to the magnetic film. The magnetic field measurement device according to claim 11 , wherein is displayed on the display unit.