WO2006003789A1 - 磁気力顕微鏡を利用した垂直磁気記録媒体中の保磁力の分布を解析する方法並びにその解析装置 - Google Patents
磁気力顕微鏡を利用した垂直磁気記録媒体中の保磁力の分布を解析する方法並びにその解析装置 Download PDFInfo
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- 230000005291 magnetic effect Effects 0.000 title claims abstract description 303
- 238000000034 method Methods 0.000 title claims description 31
- 230000005381 magnetic domain Effects 0.000 claims abstract description 131
- 230000004907 flux Effects 0.000 claims abstract description 91
- 238000001514 detection method Methods 0.000 claims abstract description 33
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- 230000005415 magnetization Effects 0.000 abstract description 54
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/12—Measuring magnetic properties of articles or specimens of solids or fluids
- G01R33/14—Measuring or plotting hysteresis curves
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y35/00—Methods or apparatus for measurement or analysis of nanostructures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
- G01Q60/00—Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
- G01Q60/50—MFM [Magnetic Force Microscopy] or apparatus therefor, e.g. MFM probes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
- G01Q60/00—Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
- G01Q60/50—MFM [Magnetic Force Microscopy] or apparatus therefor, e.g. MFM probes
- G01Q60/54—Probes, their manufacture, or their related instrumentation, e.g. holders
- G01Q60/56—Probes with magnetic coating
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/10—Plotting field distribution ; Measuring field distribution
Definitions
- the present invention relates to a method for analyzing the distribution of coercive force in a perpendicular magnetic recording medium using a magnetic force microscope and an analysis apparatus therefor, and more particularly to an image output from a magnetic force microscope.
- the present invention relates to an analysis method for visualizing the coercive force distribution of a magnetic recording medium and an analysis apparatus therefor.
- a coercive force is obtained by making a linearly polarized light beam incident on a magnetized recording medium and rotating the polarization plane of the light according to the magnetic field. Measuring.
- a magnetic field observation device using the magnetic Kerr effect it is difficult to condense the beam spot size of the light beam to the nano unit, so this observation device can observe magnetic domains with nanoscale resolution. It is not possible to obtain the nano-scale coercive force distribution.
- a magnetic force microscope is used for the surface of a sample as disclosed in, for example, J. Appl. Phys. 70 (4), 15 August 1991, P2413-2422, HW van Kesteren, or JP 2003-34258.
- a magnetic force microscope is equipped with a magnetic probe at the tip of its cantilever, and the magnetic probe utilizes the fact that this magnetic probe is finely displaced according to the magnetic distribution on the sample surface. It is known as a device that provides images corresponding to magnetic domains on the surface.
- the cause of the medium noise is that the magnetic domain structure in the medium needs to be precisely controlled. Therefore, it is considered essential to clarify the nanoscale coercive force distribution of the medium.
- MFM magnetic force microscope
- the magnetic force microscope is a device suitable for imaging the magnetic domain structure in such a perpendicular magnetic recording medium (magnetic thin film), but simply displays the magnetic field strength of the magnetic domain. However, it is not considered to display even a nanoscale coercive force distribution. If the magnetic domain structure is capable of imaging even the nanoscale coercive force distribution, it is expected that measures for precise control of the magnetic domain structure in the perpendicular magnetic recording medium will be possible, and the perpendicular magnetic recording medium with reduced recording medium noise is expected. Development is expected to progress.
- the magnetic domain structure changes at the same position of the sample while applying a large magnetic field of several kOe. It is considered desirable to continuously or strobely observe the situation.
- An object of the present invention is to provide a coercive force distribution analysis method in a perpendicular magnetic recording medium using a magnetic force microscope capable of imaging a nanoscale coercive force distribution in the perpendicular magnetic recording medium, and an analysis apparatus therefor. It is in.
- a magnet apparatus that applies a magnetic field substantially perpendicularly to a sample having a magnetic thin film capable of perpendicular magnetic recording
- a magnetic flux sensing unit that generates a magnetic flux detection signal in response to a leakage magnetic flux generated from a magnetic domain on the sample surface
- a moving mechanism that relatively moves the sample and the magnetic flux sensitive part in a plane and searches the sample surface by the magnetic flux sensitive part
- a first image generation unit for generating magnetic domain image data corresponding to a magnetic flux distribution on the sample surface based on the magnetic flux detection signal accompanying relative movement of the sample;
- Hysteresis characteristic force corresponding to the average magnetic field of the sample The selected first and second threshold values are retained, and the first and second external magnetic fields corresponding to the first and second threshold values are set.
- the image generation unit While applying the first external magnetic field from the magnet device to the sample, the image generation unit generates first magnetic domain image data, and the second external magnetic field is applied from the magnet device to the sample.
- a control unit that causes the image generation unit to generate the second magnetic domain image data and hold the first and second image data;
- An image processing unit that compares the first and second binary image data and generates a first coercive force distribution pattern corresponding to the difference;
- a coercive force distribution analyzing apparatus is provided.
- Hysteresis corresponding to the average magnetic field of samples with magnetic thin films capable of perpendicular magnetic recording Characteristic force First and second threshold values are selected, and first and second external magnetic fields corresponding to the first and second threshold values are set.
- a first external magnetic field is applied to the sample, and the leakage flux generated from the magnetic domain of the sample is detected while the sample surface is searched in a plane to generate a first magnetic flux detection signal.
- a coercive force distribution analyzing method characterized by comparing the first and second binary image data and generating a first coercive force distribution pattern corresponding to the difference between the first and second binary image data.
- FIG. 1 is a block diagram schematically showing one embodiment of an analysis apparatus for analyzing a coercive force distribution in a perpendicular magnetic recording medium using the magnetic force microscope of the present invention.
- FIG. 2 is a flowchart showing an analysis method in the analysis apparatus shown in FIG.
- FIG. 3 is a graph showing a hysteresis curve showing an average normalized magnetization used in the analysis apparatus shown in FIG. 1 and a selected average standard magnetic field.
- FIG. 4 is a diagram schematically showing an example of an MFM image obtained by the analysis apparatus shown in FIG. 1.
- FIG. 5A is a diagram showing an example of a binarized image obtained by binarizing the MFM image obtained by the analyzing apparatus shown in FIG. 1 with selected average standard magnetization.
- FIG. 5B is a diagram showing an example of a binarized image obtained by binarizing the MFM image obtained by the analyzing apparatus shown in FIG. 1 with selected average standard magnetization.
- FIG. 5C is a diagram showing an example of a binarized image obtained by binarizing the MFM image obtained by the analyzing apparatus shown in FIG. 1 with selected average normalized magnetization.
- FIG. 6A An example of the distribution pattern of the reversal magnetic domain mapped on the XY coordinate axes obtained by an analyzer that analyzes the coercive force distribution in a perpendicular magnetic recording medium using the magnetic force microscope of the present invention.
- FIG. 6B In an example of the distribution pattern of the reversed magnetic domains mapped on the XY coordinate axes obtained by the analysis device for analyzing the coercive force distribution in the perpendicular magnetic recording medium using the magnetic force microscope of the present invention. It is a figure which shows the relationship between a coercive force and an occupation area.
- FIG. 1 is a block diagram showing an analysis apparatus for analyzing the coercive force distribution in a perpendicular magnetic recording medium using the magnetic force microscope of the present invention.
- reference numeral 100 denotes a magnetic force microscope having a magnetic field application function
- reference numeral 2 denotes a magnetic force microscope exploration unit made of a non-magnetic material provided with a probe 2A at its free end.
- the cantilever 2 is supported by the piezo element 4 so as to vibrate, and the probe 2A at the tip of the cantilever is arranged on the sample 6.
- the probe 2A needs to receive an acting force according to the magnetic force of the magnetic domain.
- the probe 2A In the shape observation mode for analyzing the surface shape of 6, ie unevenness, the probe 2A needs to receive an acting force other than the magnetic force acting between the sample 6 and the probe 2A, for example, an interatomic force.
- a metal piece made of a magnetic material is used. Accordingly, the cantilever 2 is configured to be removable from the device together with the piezo element 4 or together with the piezo element 4, and can be replaced with the cantilever 2 according to the observation mode.
- This sample 6 is a ferromagnetic thin film capable of perpendicular magnetic recording, for example, CoCrPt-SiO film.
- Sample 6 has a structure formed on a two-shaped substrate and is supported on an XY stage 8 that moves the sample 6 in the XY plane.
- the surface of Sample 6 is usually in the form of irregularities in granular form in magnetic domain units. In order to prevent the irregularities from affecting the analysis of the coercive force distribution, the surface shape is preferably observed, Depending on this shape, sample 6 is in the Z direction as described below. Controlled.
- the XY stage 8 is supported by a Z stage 10 that moves the sample 6 minutely in the Z direction.
- the first distance suitable for the shape observation mode for observing the surface shape of the sample 6 can be maintained between the sample 6 and the probe 2A.
- the sample 6 and the probe 2A can be maintained.
- the first distance set in this shape observation mode uses the force acting between the sample 6 and the probe 2A in the shape observation mode that is sufficiently smaller than the second distance set in the magnetic domain observation mode. Therefore, the probe 2A is sufficiently brought close to the sample 6.
- the probe 2A is compared with the surface surface of the sample 6. Placed apart from each other.
- the distance between the surface of the sample 6 and the probe 2A can be maintained substantially constant by controlling the Z stage 10 according to the shape of the surface of the sample 6.
- the magnetic force can be measured in a state where the acting force acting between the probe 2A is substantially ignored. If the surface of sample 6 is sufficiently flat (flat in the order of several tens of nanometers), control is performed in the magnetic domain observation mode so that the distance between the surface of sample 6 and probe 2A is maintained substantially constant by Z stage 10. It does n’t have to be.
- the piezo element 4 is connected to a piezo element driver 34 and driven by a high-frequency AC signal supplied from the piezo element driver 34, and the magnetic probe 2 A at the tip thereof is vibrated up and down on the surface of the sample 6.
- the XY stage 8 and the Z stage 10 are connected to a stage control unit 36, and the Z stage 10 is driven by the stage control unit 36 so that the distance between the sample 6 and the magnetic probe 2A becomes a predetermined distance. Be controlled.
- the XY stage 8 is slightly moved in the XY plane by the stage control unit 36. Therefore, the surface of the sample 6 is scanned by the probe 2A in a state where the distance from the surface of the sample 6 is kept constant.
- the space in which the sample 6 and the cantilever 2 are arranged is maintained almost empty by an exhaust mechanism (not shown), and the electromagnet and the peripheral part are cooled by a cooling device (not shown) in order to eliminate position drift during observation.
- a cooling device not shown
- the sample 6 and the cantilever 2 are maintained in a constant temperature atmosphere so that their characteristics do not fluctuate thermally. Therefore, the sample 6 is measured in a state where it is kept constant thermally.
- the maximum magnetic field strength at the time of observation is, for example, ⁇ 6 kOe
- the sample holder and the probe are made of a non-magnetic material in order to exclude that the measurement system is affected by the magnetic field. Fixed to a magnetic force microscope (MFM) system.
- MFM magnetic force microscope
- a first pole piece 12 is disposed on the sample 6 so as to face the sample 6, and a second pole piece 14 is disposed on the sample 6 so as to face the sample 6.
- the sample 6 can be demagnetized or demagnetized by a measuring vertical magnetic field (external magnetic field) passing through the sample 6 between the first and second pole pieces 12 and 14 substantially vertically.
- the magnetic probe 2A is similarly demagnetized or magnetized by this measuring vertical magnetic field.
- the magnetic probe 2A is given a coercive force according to the measurement vertical magnetic field, and is not affected by the measurement vertical magnetic field as long as the measurement vertical magnetic field is kept constant.
- the magnetic repulsion force or magnetic attraction force is received only by the leakage magnetic field from the magnetic domain.
- the first and second pole pieces 12, 14 are magnetically coupled by a magnetic yoke 16, and electromagnets 18, 20 are provided around the first and second pole pieces 12, 14, respectively. ing.
- the electromagnets 18 and 20 are connected to a current source 22 and excited by a current from the current source 22, and the excitation causes a predetermined gap between the first and second pole pieces 12 and 14 as described later.
- a vertical magnetic field for measurement having a magnetic field strength is generated.
- the displacement of the tip of the cantilever 2 is detected by a so-called optical lever method.
- the back surface of the tip of the cantilever 2 is formed into a mirror surface to measure the movement of the tip of the cantilever 2, and the mirror surface force of the laser 24 that generates a laser beam toward the mirror surface and the vibrating cantilever 2 is also reflected.
- An optical sensor 26 for detecting the emitted laser beam is provided.
- the laser 24 is driven by a laser driver 28 and generates a laser beam having a constant intensity toward the tip of the cantilever 2.
- the detection signal from the optical sensor 26 is output to the detection signal processing unit 30.
- the detection signal processing unit 30 In the shape measurement mode for measuring the surface shape of the sample 6, the detection signal processing unit 30 outputs a surface shape signal having an output level corresponding to the unevenness of the surface of the sample 6 to the surface shape analysis unit 38 to detect the magnetic domain strength.
- the magnetic intensity detection signal corresponding to the leakage magnetic flux from the magnetic domain is output to the magnetic domain image processing generation unit 32.
- the detection signal processing unit 30 is supplied with a piezo element drive signal from the piezo element driver 34, and compares the drive signal with an output signal from the optical sensor 26 to thereby detect a surface shape signal and a magnetic intensity detection signal. Is extracted.
- the acting force acting between the sample 6 and the probe 2A is constant, and the output signal force from the optical sensor 26 is also free from noise.
- the signal waveform of the output signal and the piezo element driving signal are substantially similar, and a surface shape signal corresponding to flatness is generated.
- the acting force acting between the sample 6 and the probe 2A fluctuates, and the output signal from which the noise from the optical sensor 26 has been removed is removed. Has a signal waveform different from that of the piezo element drive signal.
- the comparator 6 or the adder (not shown) provided in the detection signal processing unit 30 compares the output signal from the optical sensor 26 with the piezoelectric element drive signal, which corresponds to the unevenness of the sample 6. A surface shape signal is generated.
- the magnetic domain observation mode if an external vertical magnetic field is applied to the sample 6 and no magnetic flux is generated in the magnetic domain force, an attractive force or a repulsion is generated between the magnetic domain and the magnetic probe 2A.
- the output signal from which noise is removed from the optical sensor 26 and the piezo element drive signal are substantially similar in signal waveform, and the magnetic intensity detection signal corresponding to the leakage flux from the magnetic domain is Virtually not generated.
- the magnetic domain observation mode when leakage magnetic flux is generated from the magnetic domain in the state where the external vertical magnetic field is applied to the sample 6, the magnetic flux is attracted between the magnetic domain and the magnetic probe 2A.
- a magnetic strength detection signal corresponding to the leakage flux of the magnetic domain force is generated. That is, similarly, a comparator or an adder (not shown) provided in the detection signal processing unit 30 compares the output signal from the optical sensor 26 with the piezo element drive signal, thereby generating a signal from the magnetic domain. A magnetic strength detection signal corresponding to the leakage flux is generated. Physically, when a leakage magnetic flux acts on the vibrating magnetic probe 2A, the mechanical resonance point of the magnetic probe 2A and the cantilever 2 is shifted, and the shift amount is changed corresponding to the leakage magnetic flux.
- the signal processing unit 30 The fluctuation of the point is detected, and the fluctuation is converted into a magnetic intensity detection signal corresponding to the leakage magnetic flux and supplied to the magnetic domain image processing generation unit 32.
- the external vertical magnetic field includes a magnetic field of zero magnetic field without generating a magnetic field as will be described later.
- the surface shape signal is supplied to the surface shape analysis unit 38, converted into a concavo-convex signal in the Z direction as a function of the XY coordinates, and stored in the memory 40.
- the surface shape signal stored in the memory 40 is read with the movement of the XY stage 8 in the magnetic domain observation mode, and the Z stage 10 is moved up and down. Therefore, as already described, the magnetic probe 2A searches for the sample 6 along the unevenness of the sample 6 so as to keep the space between the magnetic probe 2A and the sample 6 constant.
- the input magnetic intensity detection signal is converted into shadow data having a function of XY coordinates according to the level, and the area scanned by the magnetic probe 2A is shaded. Will be converted to.
- This image data is stored in the frame memory 42 as a frame image for each measurement vertical magnetic field.
- This frame image can be displayed on the display device 48 under the control of the CPU 46 in accordance with an instruction from the input / output unit 44, for example, a keyboard, and can be output to a printer (not shown) as required.
- the shadow data is binarized by the magnetic domain image processing generation unit 32 based on the standard residual magnetic flux density or the standard magnetization (MZMs) selected as the threshold value.
- MZMs standard residual magnetic flux density or the standard magnetization
- the domain of the magnetic domain larger than the reference residual magnetic flux density or the standard magnetization is converted to the first color (for example, black) and is smaller than the standard residual magnetic flux density or the standard standard magnetization.
- the domain of the magnetic domain is converted to a second color (for example, white).
- this binary image data is also stored in the frame memory 42 after processing. This binarized image data is acquired each time the reference residual magnetic flux density or the strength of the external vertical magnetic field corresponding to the reference standard magnetization is changed, and is measured by the number of preset levels of the external vertical magnetic field strength. Force created
- the magnetic domain image processing generation unit 32 a plurality of binary image data prepared as described above are extracted only two frames of binary image data whose measurement conditions are close to each other. The difference between the two frame image data is taken to determine an area corresponding to the difference, and the area is converted into the first colored area. Similarly, the measurement conditions are close to each other. Only two frames of binary image data related to the other combinations are extracted, the difference between the two frame image data is taken, the area corresponding to the difference is determined, and the area is second colored. Converted to a region. By repeating this operation, the coercive force distribution of the magnetic domain is patterned, the areas are colored with different colors, and one piece of image frame data showing the coercive force distribution is created. The data is similarly stored in the frame memory 42 and displayed on the display unit 48.
- a perpendicular magnetic recording medium (magnetic medium having a magnetic thin film coated on a substrate) as sample 6 was prepared, and average magnetic characteristics (hysteresis as shown in FIG. 2) were prepared. Characteristic) is measured with a macroscopic magnetization measuring device, for example, a vibration data type magnetometer or a surface magnetic field measuring device using the Kerr effect (steps S10 and S12).
- the average magnetic property means an average magnetic property of a magnetic material as a set of a large number of magnetic domains, and individual magnetic domains or a set of several magnetic domains whose coercive force distribution is to be reconciled. This is different from the magnetic characteristics of the minute region corresponding to.
- the average magnetic property has a hysteresis curve as shown in FIG. 3, and at least three points from such a curve, and in the following example, four standard magnetization (MZMs) points are defined.
- MZMs standard magnetization
- a magnetized image at this point is generated as follows.
- Figure 3 shows the hysteresis curve of CoCrPt-SiO
- the external vertical applied magnetic field (kOe) is shown on the horizontal axis, and the standard magnetization (MZMs ratio) is shown on the vertical axis.
- the standard magnetization indicates the ratio of the magnetic flux density (M) based on the saturation magnetic flux density (Ms) in the magnetic material.
- This sample 6 is prepared by being magnetized until saturation in advance, the external perpendicular applied magnetic field is zero, and the standard magnetization (MZMs ratio) is 1.
- the standard magnetic field is measured here, but the hysteresis curve of the magnetic flux density of the coercive force may be used instead of the hysteresis curve of the standard magnetic field. Instead, a known hysteresis curve may be used.
- N points of external vertical applied magnetic fields are selected.
- the point b corresponds to the demagnetization of the sample 6 when the second external vertical applied magnetic field is 2 (kOe), and the standard magnetization (M ZMs ratio) corresponds to approximately 0.7.
- point c corresponds to the demagnetization of sample 6 when the third external vertical applied magnetic field is -4 (k Oe)
- the standard magnetization (MZMs ratio) corresponds to substantially zero
- point d corresponds to the fourth
- the external vertical applied magnetic field corresponds to the demagnetization of sample 6 at -6 (kOe)
- the standard magnetization (MZMs ratio) corresponds to approximately 0.5.
- the force of selecting 4 points Since the difference of the image pattern is extracted as described later, it is sufficient that at least 2 points are selected. Preferably, 3 points or more are selected. This is preferable for imaging the coercivity distribution of magnetic domains.
- step S16 the surface of the sample 6 is searched by the nonmagnetic probe 2A, and the unevenness of the sample surface is analyzed by the surface shape analysis unit 38, and the X-Y coordinates are used as parameters.
- the coordinates are stored in the memory 40 as surface shape analysis data.
- the surface shape analysis data is such data that the surface shape can be displayed as an image, and the resolution of the surface shape analysis is preferably the same as that having the same resolution as the measurement of magnetic force in a magnetic force microscope. It is preferable that the image can be displayed after being processed by a surface shape image processing unit (not shown).
- a surface shape image processing unit not shown.
- an image based on the surface shape analysis data an atomic force microscope image (AFM image) is known, and a detailed description thereof will be omitted.
- AFM image atomic force microscope image
- the nonmagnetic probe 2A force is replaced with a cantilever 2 equipped with a magnetic probe 2A, and measurement is started.
- sample 6 is magnetized to the standard magnetization (MZMs ratio) of 1.
- MZMs ratio standard magnetization
- the sample 6 magnetized to this saturation magnetic flux density is held on the XY stage 8, and the leakage magnetic flux density of the surface domain is magnetic when the external vertical applied magnetic field for measurement is zero as shown in step S18.
- Measured by probe 2A The measured magnetic domain area is updated as the X—Y stage 8 moves, and the leakage flux is detected one after another using the X—Y coordinate indicating the magnetic domain area as a parameter, and the magnetic field using the X—Y coordinate as a parameter.
- the intensity detection signal is supplied to the magnetic domain image processing generator 32.
- the magnetic strength detection signal indicates that the unevenness of the surface of the sample 6 Along with this, the action component acting on the magnetic probe 2A is removed.
- the magnetic domain image processing generation unit 32 When a predetermined region of the sample 6 is scanned by the magnetic probe 2A and the magnetic flux leakage density of the magnetic domain force in the region is detected, the magnetic domain image processing generation unit 32 successively changes the level of the leakage magnetic flux. It is converted to an image signal and converted to a grayscale image signal (MFM image signal) using XY coordinates as parameters. Image data (MFM image data) composed of this image signal is stored in the frame memory 42 and displayed as an image (MFM image) on the display unit 48 in accordance with an instruction from the input unit 44.
- FIG. 4 schematically shows an example of this image.
- the level of leakage flux is proportional to the magnetic flux retention density of the magnetic domain, so this image will show the distribution of magnetic flux retention flux density.
- the area displayed in black is an area composed of the magnetic domain having the highest magnetic flux density
- the area displayed in white is the magnetic field is reversed and the magnetic flux is reversed, and the magnetic flux density in the reverse direction is The region is composed of the strongest magnetic domains.
- the force indicated by hatching between the white and black display areas This hatched area corresponds to an area having an intermediate magnetic flux density. In the hatched area, the magnetic domains have different magnetic flux densities.
- the concentration is given, but for the purpose of simplifying the figure, Figure 4 shows a single concentration.
- this image signal is binarized in the magnetic domain image processing generation unit 32.
- step S18 is executed again. That is, an external vertical magnetic field ( ⁇ 2 kOe) is applied to the sample 6 so that the standard magnetization (MZMs ratio 0.7) of the point (b) in FIG.
- This image signal is similarly binarized in the magnetic domain image processing generation unit 32.
- the image signal is binarized using the standard magnetization (MZMs ratio 0.7) at point (b) in Fig. 3 as a threshold value. That is, in the same image as shown in FIG. 4, most of the shaded area corresponds to the standard magnetization (MZMs ratio 0.7), and this standard magnetization (MZMs ratio 0.7) is the threshold value. Areas that are equal to or greater than the threshold value are areas indicated by oblique lines and areas displayed in black. Therefore, when the image signal as shown in FIG. 4 is binarized with the standard magnetization (MZMs ratio 0.7) as a threshold, the hatched and black areas in FIG.
- FIG. 5B All are displayed in black, and other areas shown in white in the same image as shown in FIG. 4 are displayed in white. Therefore, in the image of FIG. 5B, the region shown in black corresponds to the region where the magnetic domain force magnetized at the standard magnetization (MZMs ratio O. 7) or higher at the point (b) in FIG. 3 is also shown in white. This region corresponds to the region of magnetic domain force that is magnetized below the standard magnetization (MZMs ratio O. 7) at point (b) in Fig. 2. In other words, even in the average standard magnetization (MZMs ratio 0.7), the sample 6 has a domain consisting of a magnetic domain force that is inverted below the standard magnetic field (MZMs ratio O. 7) shown in white. As shown in black! /, The standard magnetization (MZMs ratio O. 7) or higher It means that an area will be created.
- MZMs ratio O. 7 or higher It means that an area will be created.
- This image signal is similarly binarized in the magnetic domain image processing generation unit 32.
- the image signal is binarized using the standard magnetization (MZMs ratio 0 and MZMs ratio 0.5) at points (c) and (d) in FIG. 3 as threshold values. That is, in the same image as shown in FIG. 4, most of the shaded area corresponds to the standard magnetization (MZMs ratio 0 and MZMs ratio 0.5), and this standard magnetization (MZMs ratio 0 and MZMs ratio 0). If 5) is set as a threshold, areas above this threshold are areas indicated by diagonal lines and areas displayed in black. Therefore, when the image signal shown in FIG.
- FIG. 4 is binarized with the standard magnetization (MZMs ratio 0 and MZMs ratio 0.5) as a threshold value, the hatched and black areas in FIG. As shown in FIGS. 5C and 5D, all are displayed in black, and in the same image as shown in FIG. 4, the other areas shown in white are displayed in white. Therefore, in the images of FIG. 5C and FIG. 5D, the area shown in black was magnetized at the normal magnetization (MZMs ratio 0 and MZMs ratio ⁇ 0.5) of points (c) and (d) in FIG.
- MZMs ratio 0 and MZMs ratio 0.5 the normal magnetization
- the region shown in white which corresponds to the region consisting of the magnetic domain cover, is magnetized with the standard magnetization (MZMs ratio 0 and MZMs ratio 0.5) below the points (c) and (d) in Fig. 3.
- the sample 6 is inverted to an average standard magnetization (MZMs ratio 0 and MZMs ratio 0.5) below the standard magnetization (MZMs ratio 0 and MZMs ratio 0.5) shown in white.
- Magnetic domain This means that there is an area consisting of the magnetic domain force magnetized to the standard magnetization (MZMs ratio 0 and MZMs ratio 0.5) shown in black or higher. ing.
- the binary image shown in FIG. 5A is compared with the binary image shown in FIG. 5B, and image data corresponding to the difference is generated.
- MZ Ms l.
- MZMs l. 0
- the domain of the reversed magnetic domain is displayed in the first color.
- the normalized magnetization is from MZMs O. 7 in the process in which the external vertical magnetic field is transitioned from (1 2 kOe) to (1 4 kOe) (the process of applying the reversal magnetic field).
- M ZMs ⁇ O the distribution of the magnetic domain data in which the magnetic flux density of the magnetic domain is switched remains.
- the standard magnetic field is MZMs ⁇ O in the process of transition of the external vertical magnetic field from (1 4 kOe) to (1 6 kOe) (the process of applying the reversal magnetic field).
- MZMs 0.5 to MZMs 0.5 the distribution of magnetic domain data in which the magnetic flux density of the magnetic domain is switched remains. The same is repeated for the N-point standard, which is shown in Figs. 6A and 6B.
- the sample 6 is magnetized to a positive saturation magnetic flux density, the external magnetic field is demagnetized from the positive direction to the negative direction, and is further negatively magnetized.
- the magnetic domain structure is measured with the measuring magnetic field.
- sample 6 is magnetized to a negative saturation magnetic flux density, the external magnetic field is demagnetized from the negative direction to the positive direction, and then positively magnetized. It is clear that the magnetic domain structure may be measured with an arbitrary measurement magnetic field while magnetizing.
- the pattern in the image is dichroized so that the image in an arbitrary magnetic field shows a magnetic domain. (Binary value). That is, the corresponding standard magnetization (MZMs) point is classified as a threshold value into larger, magnetic domain region, smaller domain region, and magnetic domain region than this standard magnetization (MZMs).
- each of the two color regions represents an upward and downward magnetic domain region.
- the bright and dark areas represent up and down magnetic domain areas.
- the value of (3 ⁇ 3 / (3 +3 is macroscopic magnetic field measurement (for example, measurement of surface magnetic field by vibration material type magnetometer or Kerr effect).
- the binarized data is subjected to a calibration process so that an average standard magnetization (M / Ms) that is preferable to dichroize the image data is obtained so that it matches the value obtained in (Device). It is preferable.
- the area An—n obtained by the difference processing of is measured, and all n images are combined into an image.
- the distribution of coercive force in the sample can be obtained.
- a mechanism for detecting leakage magnetic flux with the magnetic probe 2A will be described.
- the mechanism for detecting the leakage magnetic flux is to irradiate the sample surface with near-field light that can detect the distortion of the probe itself, and the polarization plane of the near-field light is reflected on the sample surface by the Kerr effect. The rotation angle can be detected by the detection system.
- the nanoscale coercive force distribution in the perpendicular magnetic recording medium is obtained using a magnetic force microscope. You can make a video. Therefore, the magnetic domain structure in the perpendicular magnetic recording medium can be elucidated to reduce the noise of the perpendicular magnetic recording medium and contribute to the development of an ultra-high density recording medium.
- the magnetic reversal process can be observed by continuous or strobe observation in a magnetic field, and image data in various magnetic fields. From the difference between them, a coercive force distribution image in the sample can be obtained. If a coercive force distribution image is obtained, it is possible to quantitatively clarify nanoscale magnetic fluctuations in patterned media and ultra-high-density magnetic recording media.For example, it is possible to directly observe and quantitatively evaluate active volume. Become.
- An analysis method and an analysis apparatus for analyzing the image output from the magnetic force microscope to visualize the coercive force distribution of the perpendicular magnetic recording medium are provided. Therefore, the method and apparatus of the present invention can contribute to the development of perpendicular magnetic recording media and the improvement of their characteristics.
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Abstract
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US11/631,101 US7560921B2 (en) | 2004-06-30 | 2005-06-15 | Method and device for analyzing distribution of coercive force in vertical magnetic recording medium using magnetic force microscope |
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TWI259285B (en) * | 2005-04-07 | 2006-08-01 | Univ Nat Yunlin Sci & Tech | Method of measuring sub-micrometer hysteresis loops of magnetic films |
JP5045902B2 (ja) * | 2007-05-25 | 2012-10-10 | 独立行政法人物質・材料研究機構 | 走査型プローブ顕微鏡における走査方法及び強磁場走査型プローブ顕微鏡装置 |
JP2011003533A (ja) * | 2009-05-20 | 2011-01-06 | Jeol Ltd | 磁区観察装置 |
DE102009046267B4 (de) * | 2009-10-30 | 2013-12-24 | Ernst-Moritz-Arndt-Universität Greifswald | Verfahren zur Messung magnetischer Informationen, insbesondere der magnetischen AC-Suszeptibilität, von magnetischen Nanopartikeln (Markern) |
JP5168363B2 (ja) * | 2010-03-15 | 2013-03-21 | トヨタ自動車株式会社 | 保磁力分布磁石の保磁力特定方法 |
JP2013089805A (ja) * | 2011-10-19 | 2013-05-13 | Toyota Motor Corp | 永久磁石の検査方法 |
EP2808692B1 (en) | 2012-01-26 | 2016-11-16 | TDK Corporation | Magnetic measurement device |
CN108918424B (zh) * | 2018-04-24 | 2020-10-02 | 金华职业技术学院 | 一种磁性线材的磁畴成像方法及磁畴壁形状判别方法 |
US10976238B2 (en) * | 2019-01-30 | 2021-04-13 | Xi'an Jiaotong University | Measurement apparatus for micro- and nano-scale material and measurement method thereof |
JP7291618B2 (ja) * | 2019-12-24 | 2023-06-15 | 株式会社日立製作所 | 画像取得システム及び画像取得方法 |
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