JPH06176328A - Measurement instrument using magneto-optical effect - Google Patents

Abstract

PURPOSE:To obtain a measurement instrument using a magneto-optical effect and improving the deterioration in measurement precision due to the noise of light. CONSTITUTION:This instrument is the measurement instrument using the magneto-optical effect irradiating a beam deflected by a polarizer 3 to a sample 6 and measuring the beam deflected by the sample 6 through an analyzer 13. Then, the instrument is provided with a branching means 7 branching the beam deflected by the sample into two beams, a first detection means 11 detecting one side light quantity of the branched beams and a second detection means 15 detecting the other side light quantity after passing through the analyzer 13, and the magneto-optical effect is measured by the difference or the division of the detected amount of the first and the second detection means. The noise is reduced by taking the difference or the division of both means since the light quantity due to the magnetization change of the magnetic material of the sample and the noise of light are incorporated in the detected amount of the second detection means 15 and the light quantity due to the noise of light is incorporated in the detected amount of one side first detection means 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device for observing a magnetic domain of a magnetic film of a magnetic head or measuring magnetization by utilizing a magneto-optical effect such as Kerr effect, and in particular, enables a highly accurate measurement. It is a thing.

[0002]

2. Description of the Related Art As an effect of changing light propagation characteristics due to magnetic properties, when a magnetic material is irradiated with light, a Kerr effect in which a deflecting surface of reflected light rotates according to the strength of a magnetic field or a magnetic material The Faraday effect or the like in which the deflecting surface of the transmitted light rotates according to the strength of the magnetic field is known, and a large number of devices have been created to measure the magnetic characteristics of the magnetic substance by utilizing such magneto-optical effect.

In these measuring devices, a deflector for deflecting light applied to a magnetic material and an analyzer for detecting reflected light or transmitted light from the magnetic material are combined to measure the intensity of light changed by the magnetic material. The strength of the magnetic field is calculated from the measured value.

A magnetization measuring device utilizing the Kerr effect, which is one of the devices of this type, irradiates polarized light to a minute area on the surface of a magnetic material sample, and changes the rotation angle of the polarization plane of the reflected light by the amount of light. It is measured by converting it into the change of light quantity by the detector. The amount of change in the rotation angle corresponds to the direction and magnitude of magnetization in the irradiation area on the surface of the magnetic material, and the magnetization state of the magnetic material sample can be microscopically measured through this measurement.

Further, in the magnetic domain observation apparatus utilizing the Kerr effect, light is irradiated to a wide area of a magnetic material sample, and the rotation angle of the polarization plane of the reflected light, which changes depending on the direction and size of the magnetization of each magnetic domain, changes. The amount of change is captured by the camera as a change in the amount of light and displayed as an image showing the magnetic domain structure.

[0006]

However, the change in the rotation angle of the deflecting surface due to the magneto-optical effect is very small. Therefore, when the change in the rotation angle of the deflecting surface is converted into the change in the light amount, the change amount in the light amount is changed. Also becomes smaller.

Therefore, if there is noise due to fluctuations in the light emitting state of the light source, a change in reflectance due to microvibration of the measurement sample, a change in reflectance due to irregularities on the surface of the measurement sample, or an inclination of the measurement sample, Light noise resulting from these is superimposed on the measurement signal, and the superimposed noise occupies a large proportion of the magnitude of the change in the measurement signal, which allows accurate measurement of the change in light quantity. It will be difficult.

In addition, in the magnetic domain observation apparatus, in addition to these, illumination unevenness caused by light intensity unevenness of the light source becomes a cause of obstructing clear and accurate observation of the magnetic domain pattern.

The influence of such noise of light is particularly remarkable in a measuring apparatus using the Kerr effect because the noise is amplified by reflection.

The present invention solves these conventional problems, and an object of the present invention is to provide a measuring apparatus utilizing the magneto-optical effect, in which the deterioration of the measuring accuracy due to the noise of light is improved.

[0011]

Therefore, according to the present invention, in a measuring apparatus utilizing a magneto-optical effect, a sample is irradiated with light deflected by a deflector, and the light deflected by the sample is measured through an analyzer. Means for splitting the light deflected by the light into two, a first detecting means for detecting one light quantity of the branched light, and the other light quantity of the branched light after being passed through an analyzer. The second detection means is provided, and the magneto-optical effect is measured by the difference or removal of the detection amounts of the first detection means and the second detection means.

Further, the Kerr effect is used as the magneto-optical effect, and the image signal for displaying the magnetic domain of the sample is generated by the difference or removal of the detection amounts of the first detecting means and the second detecting means.

[0013]

The amount of light detected by the second detecting means of this measuring apparatus includes, in addition to the change in the amount of light due to the change in the magnetization of the magnetic substance of the sample, the light noise and the minute amount of the sample caused by the fluctuation of the light emitting state of the light source. Light noise is included due to changes in reflectance due to vibration, changes in reflectance due to irregularities on the surface of the sample, and changes in reflectance due to the tilt of the sample.

On the other hand, the amount of light detected by the first detecting means is
Although the change in the amount of light due to the change in the magnetization of the magnetic material of the sample is not included, all of the above-described light noise is included.

Therefore, the signal due to light noise can be reduced by subtracting or subtracting from the measurement signal by the second detection means with the measurement signal by the first detection means as the background, and the magnetization of the magnetic material of the sample can be reduced. It is possible to more accurately measure the change in the light amount due to the change.

The same applies to the case of observing the magnetic domain by utilizing the Kerr effect, and an image signal is generated by the difference or division between the signal detected by the first detecting means and the signal detected by the second detecting means. This makes it possible to display a clear image of the magnetic domain pattern on the surface of the sample magnetic body.

[0017]

【Example】

(First Embodiment) The apparatus shown in the first embodiment is a magnetization measuring apparatus utilizing the Kerr effect. As shown in FIG. 1, this apparatus includes a light source 1 that emits laser light, a condenser lens 2, and a deflector that linearly deflects the laser light as an optical system that introduces irradiation light into a sample (thin film magnetic head) 6. 3, a total reflection mirror 4, and an objective lens 5, and as a system for reading information from the reflected light, a half mirror 7 that splits the reflected light that has passed through the objective lens 5 into two light beams, and , A photoelectric conversion element 11 for changing the change in the amount of light into a change in an electric signal, an analyzer 9 for deflecting the other light beam, a condenser lens 14, and an analyzer 9. A photoelectric conversion element 15 for converting a change in the amount of light generated into an electric signal, and a signal processor for processing the signals collected by each photoelectric conversion element 11, 15.
And a head driving device 16 for keeping the thin film magnetic head 6 of the sample in a driven state.

The light emitted from the laser light source 1 is condensed by the lens 2, passes through the polarizer 3, becomes linearly polarized light, is reflected by the total reflection mirror 4 and enters the objective lens 5, and then the thin film magnetic The minute area of the magnetic film of the head 6 is irradiated. The thin film magnetic head is driven by the head driving device 16.

The reflected light from the magnetic film passes through the objective lens 5 and is split into a light beam 8 and a light beam 9 by the half mirror 7.
The light flux 8 is condensed by the lens 10 and is incident on the photoelectric surface of the photoelectric conversion element 11, and the photoelectric conversion element 11 converts the change in the light amount into the change in the electric signal. The electric signal from the photoelectric conversion element 11 is sent to the signal processor 12.

One light beam 9 passes through the analyzer 13. The polarization plane of the analyzer 13 is adjusted in advance so as to be orthogonal to the polarization plane of the polarizer 3. Therefore, only the light whose polarization plane is rotated can pass through the analyzer 13 due to the Kerr effect due to the magnetization of the surface of the magnetic film of the thin film magnetic head 6.
The light passing through the analyzer 13 is condensed by the lens 14 on the photoelectric surface of the photoelectric conversion element 15, and the photoelectric conversion element 15 converts the change in the light amount into the change in the electric signal. This photoelectric conversion element
The electric signal from 15 is sent to the signal processor 12.

In the signal processor 12, the electric signal from the photoelectric conversion element 11 is included in the electric signal of the photoelectric conversion element 15 by using the electric signal from the photoelectric conversion element 11 as the background and subtracting the difference from the electric signal from the photoelectric conversion element 15. It is possible to separate only the electric signal indicating the change in the magnetization of the magnetic film of the thin film magnetic head 6.

2, 3, and 4, a thin film magnetic head 6 is shown.
2 shows the result of magnetization measurement in a state where the head drive device 16 was driven by applying a current of 1 MHz and 20 mA. FIG. 2 shows an electric signal obtained by the photoelectric conversion element 11. The change of the electric signal in FIG. 2 is due to the noise of light as described above. FIG. 3 shows an electric signal obtained by the photoelectric conversion element 15. In addition to the change in the electric signal due to the noise of light as in FIG. 2, a change corresponding to the change in the magnetization of the magnetic film can be observed. FIG. 4 is a result of taking a difference between the electric signal of FIG. 3 and the electric signal of FIG. In FIG. 4, the change in the electric signal due to the noise of light is removed, and only the change in the electric signal corresponding to the change in the magnetization of the magnetic film can be observed.

(Second Embodiment) The apparatus shown in the second embodiment is
This is a magnetic domain observation device that utilizes the Kerr effect. This device
As shown in FIG. 5, as a system for reading information from the reflected light of the thin film magnetic head 6 of the sample, a half mirror 7 that splits the reflected light that has passed through the objective lens 5 into two light beams,
A condenser lens 10 for condensing one of the light fluxes, a CCD camera 17 for converting a change in the amount of light of each pixel into a change in an electric signal,
An analyzer 9 for deflecting the other light flux, a condenser lens 14, and a CCD for converting a change in light passing through the analyzer 9 into an electric signal.
A camera 19 and an image processor 18 that generates an image signal from the signals collected by the CCD cameras 17 and 19 are provided. The other structure is the same as that of the apparatus of the first embodiment (FIG. 1).

In this magnetic domain observation apparatus, the light emitted from the laser light source 1 is condensed by the lens 2, linearly polarized by the polarizer 3, and then reflected by the total reflection mirror 4,
A wide area of the magnetic film of the thin-film magnetic head 6 is irradiated through the objective lens 5. Thin-film magnetic head is a head drive device 16
Is driven by.

The reflected light from the magnetic film passes through the objective lens 5 and is split by the half mirror 7 into a light beam 8 and a light beam 9. The light flux 8 is condensed by the lens 10 and is incident on the photocathode of the CCD camera 17, and the CCD camera 17 converts the change in the light amount for each pixel into a change in the electric signal. This CC
The electric signal from the D camera 17 is sent to the image processor 18.

One light beam 9 passes through the analyzer 13. The polarization plane of the analyzer 13 is adjusted in advance so as to be orthogonal to the polarization plane of the polarizer 3, and only the light whose polarization plane is rotated by the Kerr effect due to the magnetization of the surface of the magnetic film of the thin film magnetic head 6 is detected. It can pass through photons 13. This analyzer
The light that has passed through 13 is condensed on the photocathode of the CCD camera 19 by the lens 14, and the CCD camera 19 converts the change in the light amount for each pixel into a change in the electric signal. This CC
The electric signal from the D camera 19 is sent to the image processor 18.

The image processor 18 generates an image signal by subtracting the difference from the electric signal from the CCD camera 19 or subtracting the electric signal from the CCD camera 17 in the background. By doing so, only the electric signal due to the change in the magnetization of the magnetic film of the thin film magnetic head 6 included in the electric signal of the CCD camera is separated, so that a clear and accurate magnetic domain pattern image with less noise can be obtained. .

[0028]

As is apparent from the above description of the embodiments, in the measuring apparatus using the magneto-optical effect of the present invention, the change in the rotation of the deflecting surface due to the magneto-optical effect can be detected in the state where the noise of light is removed. Since it is possible to measure with high accuracy, it is possible to accurately and precisely measure changes in the direction and magnitude of magnetization in a minute area of a magnetic substance, and to display a magnetic domain pattern of a magnetic substance clearly and accurately. You can In particular, the appearance of the effect is remarkable in the measuring apparatus using the Kerr effect.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a magnetization measuring device according to a first embodiment of the present invention,

FIG. 2 is a measurement result by the photoelectric conversion element 11 of the magnetization measuring apparatus of the first embodiment,

FIG. 3 is a measurement result by the photoelectric conversion element 15 of the magnetization measuring device of the first embodiment,

FIG. 4 is a measurement result of signal processing performed by a signal processor of the magnetization measuring device according to the first embodiment;

FIG. 5 is a configuration diagram of a magnetic domain observation apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Laser Light Source 2, 10, 14 Lens 3 Polarizer 4 Total Reflection Mirror 5 Objective Lens 6 Thin Film Magnetic Head 7 Half Mirror 8, 9 Luminous Flux 11, 15 Photoelectric Conversion Element 12 Signal Processor 13 Analyzer 16 Head Drive 17, 19 CCD camera 18 Image processor

Claims (2)

[Claims] 1. A measuring device using a magneto-optical effect, which comprises irradiating a sample with light deflected by a deflector and measuring the light deflected by the sample through an analyzer, wherein two beams deflected by the sample are used. And a first detecting means for detecting one light amount of the branched light, and a second detecting means for detecting the other light amount of the branched light after passing through the analyzer. A measuring device, wherein the magneto-optical effect is measured by the difference or removal of the detection amounts of the first detection means and the second detection means. 2. A Kerr effect is used as the magneto-optical effect, and an image signal for displaying a magnetic domain of the sample is generated by a difference or division of detection amounts of the first detection unit and the second detection unit. The measuring device according to claim 1.