JP2001215263A - Magneto-optical microscope magnetometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical microscope magnetometer capable of measuring a hysteresis loop of a hyperfine local area (on the order of 0.3×0.3 μm). SOLUTION: This magneto-optical microscope magnetometer is characterized by being equipped with an electromagnet unit 130 for impressing a magnetic field on a magnetic material 117', an optical polarization microscope 110 for outputting the magnetized state of a surface of the material 117' as an optical polarization image signal, a CCD camera unit 120 for photographing the image signal on a real time basis, a data converting means 140 for converting a change in the image signal photographed by the camera unit 120 into a hysteresis loop, an output means 150 for outputting a result of conversion by the converting means 140, and a magnetic field control means 160 for outputting a control signal to the electromagnet unit 130 in order to remote-control the intensity of the magnetic field impressed on the material 117.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical microscope magnetometer, and more particularly to an ultra-fine local area (about 0.3.times.0.3 .mu.m).
and m) a magneto-optical microscope magnetometer capable of measuring the hysteresis loop.

[0002]

2. Description of the Related Art Magnetic materials are used as traditional industrial materials such as permanent magnets, transformers, and motors. Recently, active research is being conducted on advanced materials such as information storage materials or magnetic sensing sensors. Is the material that is being used.

[0003] In particular, in recent years, in the development of information storage materials and large-capacity information storage technology, the demand for which is rapidly increasing with the development of computers and the Internet, etc., an ultra-fine magnetic control technology is inevitably required. Research on the local properties of materials is an urgent situation.

[0004] Therefore, researches on equipment capable of measuring magnetic properties in a local area, that is, a magnetic microscope, are being actively conducted. As such a magnetic microscope, (i) a magneto-optical microscope applied and used from an optical microscope,
(Ii) A magnetic force microscope and a proximity light microscope using the principle of a scanning microscope, and (iii) an electron scanning microscope, a Lorentz transmission microscope, and a low energy electron microscope that apply an electron microscope have been developed and used.

[0005]

However, among the conventional magnetic microscopes, other microscopes except for the magneto-optical microscope are greatly restricted by the strength of the magnetic field that can be applied to the sample. It is not possible to measure the response of the magnetic material, ie the hysteresis loop.

The hysteresis loop is a curve indicating the magnetization state of a magnetic material that changes according to the intensity of a magnetic field applied from the outside. One of the most traditional and typical measurement materials for measuring the magnetic properties of a magnetic material is One. From such a hysteresis loop, information such as a coercive force, a magnetization reversal method, and a magnetic area configuration can be obtained.

Until now, a vibrating magnetometer or a magneto-optical magnetometer has been generally used to measure the hysteresis loop. However, such existing magnetometers and the like can macroscopically measure the entire region of a magnetic material, but cannot measure a hysteresis loop in an ultra-fine local area.

[0008] In summary, a conventional magnetic microscope can observe magnetic properties in an ultra-fine local area, but cannot measure a hysteresis loop. On the other hand, the conventional magnetometer can measure the hysteresis loop,
It was not possible to measure the hysteresis loop in the hyperfine local area.

Accordingly, an object of the present invention is to simultaneously perform the functions of a conventional magneto-optical microscope and a magneto-optical magnetometer,
It is an object of the present invention to provide a new device capable of measuring a hysteresis loop of a hyperfine local area, that is, a magneto-optical microscope magnetometer.

[0010] Other objects of the present invention will become apparent from the description of the specification, drawings, and particularly from the claims.

[0011]

In order to achieve the above object, the present invention comprises an electromagnet unit, an optical polarization microscope, a CCD camera unit, a data conversion unit, an output unit, and a magnetic field control unit. It has the feature of doing.

More specifically, in order to solve the above-mentioned problems, the present invention is achieved by employing the following novel characteristic constituent means.

That is, a first feature of the present invention is that an electromagnet unit for applying a magnetic field to a magnetic material, an optical polarization microscope for outputting a magnetization state of the surface of the magnetic material as an optically polarized image signal, and an optically polarized light microscope for realizing the image signal. A CCD camera unit for photographing with time, data conversion means for converting a change in a video signal photographed by the CCD camera unit into a hysteresis loop, output means for outputting a result converted by the data conversion means, In order to remotely control the intensity of a magnetic field applied to a material, a magneto-optical microscope magnetometer includes a magnetic field control unit that outputs a control signal to the electromagnet unit.

A second feature of the present invention is the first feature of the present invention.
Wherein the optical polarization microscope according to the characteristics of the light source, a polarizer that linearly polarizes the light generated from the light source, a beam splitter that reflects the linearly polarized light, a surface of the magnetic material that reflects the reflected light An objective lens for condensing the light, a light analyzer for linearly re-polarizing the light reflected from the surface of the magnetic material and converting the light into an optically polarized image signal, and a camera lens for condensing the image signal with the CCD camera unit And the configuration of a magneto-optical microscope magnetometer comprising:

A third feature of the present invention is the first feature of the present invention.
The CCD camera unit according to the above feature, comprising an image amplifier for amplifying a video signal output from the optical polarization microscope, a plurality of optical elements, a CCD camera for photographing the amplified video signal, and the CCD camera Another object of the present invention is to adopt a configuration of a magneto-optical microscope magnetometer including a video data converter for converting a captured video signal into a digital signal.

A fourth feature of the present invention is the first feature of the present invention.
Wherein the electromagnet unit includes an electromagnet that generates a magnetic field, and a power supply that receives an input of a control signal output from the control unit and supplies a corresponding power to the electromagnet. The configuration of the magneto-optical microscope magnetometer is adopted.

[0017]

[Outside 2]

According to the above-mentioned characteristic constitution means, in the magneto-optical microscope magnetometer of the present invention, each optical element of the CCD camera used in the conventional magneto-optical magnetometer is replaced with the conventional magneto-optical magnetometer. The function of the photomultiplier used is performed, whereby the functions of the conventional magneto-optical microscope and magneto-optical magnetometer are simultaneously performed. Therefore, it is possible to measure a hysteresis loop in an ultra-fine local area observed by an optical polarization microscope.

Not only this, the hysteresis loop can be measured simultaneously for all the optical elements of the CCD camera, and the distribution of the coercive force with respect to the entire surface area of the magnetic material can be found.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a magneto-optical microscope magnetometer according to an embodiment of the present invention.

Referring to FIG. 1, a magneto-optical microscope magnetometer includes an electromagnet unit 130 for applying a magnetic field to a magnetic material 117 ', and an optical polarization microscope for outputting the magnetization state of the surface of the magnetic material 117' as an optical polarization image signal. 110,
A CCD camera unit 120 for capturing a video signal observed through the optical polarization microscope 110 in real time;
Data conversion means 14 for converting a change in a video signal captured by camera unit 120 into a hysteresis loop
0 and an output means 150 for outputting a result converted by the data conversion means 140, that is, a hysteresis loop.
A data storage unit 170 for storing a video signal captured by the CCD camera unit 120; and a magnetic material 117 '
And a magnetic field control means 160 for outputting a control signal to the electromagnet unit 130 in order to remotely control the intensity of the magnetic field applied to the magnetic field.

The optical polarization microscope 110 includes a light source 111 composed of a 100 [W] mercury lamp, a polarizer 114 composed of a plate-type polarizer having an extinction ratio of 0.01%, and an analyzer 115.
, A beam splitter 116, and an objective lens 112 having an aperture of 0.95 and a spatial resolution of 0.3 μm.
A sample support 117 on which the magnetic material 117 'is placed;
And a camera lens 113.

The light generated by the light source 111 is
It becomes a linear polarization state through 14 and is vertically reflected by the beam splitter 116. The reflected light passes through the objective lens 112 and is focused on the surface of the magnetic material 117 '.

The light reflected from the surface of the magnetic material 117 'passes through the objective lens 112 again, passes through the beam splitter 116, and reaches the analyzer 115. Analyzer 11
5 is converted into an optically polarized video signal, that is, a light / dark signal of the light, and transmitted through the camera lens 113 to the CC.
The light is focused on the D camera unit 120.

The reason why the light linearly polarized by the polarizer 114 is converted to a light / dark signal of the light by the analyzer 115 is due to the magneto-optical effect. This is specifically described as follows.

The magneto-optical effect refers to a phenomenon in which light reflected from a magnetic material changes its polarization state under the influence of a magnetized magnetic material. Generally, when linearly polarized light is reflected by a magnetic material, due to such magneto-optical effects,
The polarization axis rotates by the Kerr rotation angle.

Accordingly, the light that has passed through the polarizer 114 and entered the magnetic material 117 'in a linearly polarized state is
The magnetization state of the 17 ′ hyperfine local area causes the linear polarization axis to rotate. When the light having the rotated linear polarization axis becomes linearly polarized again by the analyzer 115, the brightness of the light changes. Occurs. After all, the optical polarization microscope 11
0 through the light and dark of the image output from the magnetic material 117.
'The magnetization state of the surface can be observed.

The CCD camera unit 120 includes an image amplifier 121 capable of amplifying by 10,000 times or more, and 640 × 480.
It comprises a CCD camera 122 including a plurality of optical elements and a video data converter 123 for converting into a 256-level digital value.

The light intensity of the optically polarized video signal input from the optically polarized light microscope 120 is amplified by the image amplifier 121, and the amplified video signal is photographed in real time by the CCD camera 122. The video signal captured by the CCD camera 122 is converted into a digital signal by the video material converter 123. Such a digital signal is stored in the data storage unit 170.

The CCD camera 122 measures the light intensity of the video signal from the minute optical elements arranged at regular positions, and substitutes the measured light intensity into the area of the corresponding position in light or dark. The method of producing a video which can be seen with the naked eye by this means is the photographing principle.

The electromagnet unit 130 receives an input of an electromagnet 131 for generating a magnetic field and a control signal output from the control means 160, and supplies a corresponding power supply to the electromagnet 131.
And a power supply 132 for supplying power to the power supply.

Here, the electromagnet 131 is cooled by a water-cooling type cooling system, and is located below the sample support 117.
A magnetic field of ± 5 KOe can be applied to the magnetic material 117 'via the electromagnet 131.

[0034]

[Outside 3]

In the equations (1) and (2), I is a CCD
The intensity of light measured at one optical element of the camera 122, I
⁰ is the light intensity compensation value of the corresponding optical element of the CCD camera 122,
C is a Kerr rotation proportional constant, α is a Faraday constant generated by the objective lens 112 of the optical polarization microscope, and Δθ is a polarizer 1
The polarization angle between θ 14 and the analyzer 115, θ _M is the magnetic material 11
7 'is a Kerr rotation angle in a state where the magnetization is saturated, and H indicates the intensity of the magnetic field applied to the magnetic material 117'.

FIGS. 2 to 5 are diagrams for explaining the analysis results measured by the magneto-optical microscope magnetometer of FIG.

Here, FIG. 2 shows the magnetic material 117 'of FIG.
CCD camera 12 based on the intensity (H) of the magnetic field applied to
2 is a graph showing the change in light intensity (I) measured from one optical element in real time, and FIG. 3 shows the measurement results of FIG. This is a hyperfine local area hysteresis loop obtained by conversion by the data conversion means 140 using 2).

On the other hand, the coercive force of the hyperfine local area can be obtained from the hysteresis loop.
Co / 11 保 Pd) The distribution of the coercive force of the ultrafine local area measured from the ₂₀ samples is graphically shown in FIG.

Referring to FIG. 4, it can be seen that the coercivity distribution matches well with the form of the mathematical Gaussian function. Such a coercive force distribution is a useful data for the Priesach theory, which is a classical hysteresis loop analysis method, and provides information on the structural inhomogeneity of a magnetic material with respect to magnetization reversal.

FIG. 5 shows that the magnitude of the coercive force of the ultrafine local area is determined by comparing the coercive force of the sample with the entire area of the sample so that the distribution of the coercive force of FIG. It is the figure which showed the divided spatial distribution.

The embodiments of the present invention have been described above. However, the present invention is not necessarily limited to the above-described means, but may achieve the object of the present invention and have the effects described below. It can be changed and implemented as appropriate.

[0042]

As described above, according to the present invention, each optical element of the CCD camera used in the conventional magneto-optical magnetometer is replaced by the function of the photomultiplier pipe used in the conventional magneto-optical magnetometer. , The functions of the conventional magneto-optical microscope and magneto-optical magnetometer are simultaneously performed. Therefore, there is an effect that the hysteresis loop in the ultra-fine local area observed by the optical polarization microscope can be measured.

Not only that, the hysteresis loop can be measured simultaneously for all the optical elements of the CCD camera, and the distribution of the coercive force with respect to the entire area of the surface of the magnetic material can be obtained.

The present invention also enables the verification of the microscopic magnetic properties of ultra-high-integration advanced devices, which have been actively studied recently, so that the magnetic characteristics of industrial products can be analyzed, optimized, and quantified. Inspection becomes possible, and magnetic stability and reliability are improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magneto-optical microscope magnetometer according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining an analysis result measured by a magneto-optical microscope magnetometer in FIG. 1;

FIG. 3 is a diagram for explaining an analysis result measured by the magneto-optical microscope magnetometer of FIG. 1;

FIG. 4 is a diagram for explaining an analysis result measured by the magneto-optical microscope magnetometer of FIG. 1;

FIG. 5 is a diagram for explaining an analysis result measured by the magneto-optical microscope magnetometer of FIG. 1;

[Explanation of symbols]

 Reference Signs List 110 optical polarization microscope 111 light source 112 objective lens 113 camera lens 114 polarizer 115 analyzer 116 beam splitter 117 sample support 117 ′ magnetic material 120 CCD camera unit 121 image amplifier 122 CCD camera 123 ... Video data converter 130 ... Electromagnet unit 131 ... Electromagnet 132 ... Power supply 140 ... Data conversion means 150 ... Output means 160 ... Magnetic field control means 170 ... Data storage means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference)

Claims (5)

[Claims] 1. An electromagnet unit for applying a magnetic field to a magnetic material, an optical polarization microscope for outputting a magnetization state of the surface of the magnetic material as an optical polarization video signal, and a CCD camera unit for capturing the video signal in real time; Data conversion means for converting a change in a video signal photographed by the CCD camera unit into a hysteresis loop; output means for outputting a result converted by the data conversion means; and an intensity of a magnetic field applied to the magnetic material. And a magnetic field control means for outputting a control signal to the electromagnet unit for remote control, comprising: a magneto-optical microscope magnetometer. 2. An optical polarization microscope, comprising: a light source; a polarizer for linearly polarizing light generated from the light source; a beam splitter for reflecting the linearly polarized light; and a magnetic material for reflecting the reflected light. An objective lens for condensing the light reflected from the surface of the magnetic material; an analyzer for linearly polarizing the light reflected from the surface of the magnetic material again to convert the light into an optically polarized image signal; and condensing the image signal with the CCD camera unit. The magneto-optical microscope magnetometer according to claim 1, comprising: a camera lens. 3. The CCD camera unit includes: an image amplifier that amplifies a video signal output from the optical polarization microscope; a CCD camera that includes a number of optical elements, and captures the amplified video signal; The magneto-optical microscope magnetometer according to claim 1, further comprising: a video data converter that converts a video signal captured by a camera into a digital signal. 4. The electromagnet unit includes: an electromagnet that generates a magnetic field; and a power supply that receives a control signal output from the control unit and supplies power corresponding to the input to the electromagnet. The magneto-optical microscope magnetometer according to claim 1, wherein: (5)