JP6528334B2 - Evaluation apparatus and evaluation method for probe for magnetic force microscope, and magnetic force adjustment method for control of magnetic force microscope and magnetic force microscope - Google Patents

Description

The present invention relates to an apparatus used for characterizing a probe for a magnetic force microscope that measures a magnetic field generated from a sample, and a method applied to the characterization.
Specifically, according to the present invention, excitation is performed in evaluation of a probe for a magnetic force microscope made of a ferromagnetic material (hard magnetic material, soft magnetic material), paramagnetic material, material exhibiting superparamagnetism, or diamagnetic material. The present invention relates to a technique for applying an alternating magnetic field of varying strength to a probe and evaluating the characteristics of the probe based on a spectrum obtained from the vibration of the probe.
Further, specifically, in the evaluation of a soft magnetic probe, a paramagnetic probe, or a superparamagnetic probe, the present invention applies a DC magnetic field and an AC magnetic field to the excited probe in a superimposed manner, The present invention relates to a technique for evaluating the characteristics of a probe based on the spectrum obtained from the vibration of the probe when changing the respective intensities.

  Further, according to the present invention, the saturation of the magnetization of the thin film of the soft magnetic material formed on the probe tip is detected by observing the intensity change of the side band of the spectrum of the probe vibration, and the detection result of the saturation of the probe magnetization The present invention relates to a magnetic force microscope and a control method for controlling a control magnetic field of a magnetic force microscope that can adjust a control magnetic field to be applied to a probe based on the following.

A magnetic force microscope (MFM) 7 shown in FIG. 1 is known as a technique for measuring AC magnetic characteristics (AC magnetic profile) of a magnetic substance sample (see Patent Document 1: WO 2013/047538).
In the MFM 7, the surface of the sample 72 is scanned by the probe tip 711 provided at the tip of the excited probe 71 (cantilever). In FIG. 1, the sample 72 is a magnetic recording head of a hard disk that generates an alternating magnetic field. An alternating magnetic field H_AC generated by the sample 72 is applied to the probe tip 711. As the probe tip, one that is mainly ferromagnetic and has hard magnetic characteristics is used.
Vibration (vibration modulation) of the probe 71 was detected by a vibration detector consisting of a laser (LASER) 731 and a photodiode (PD) 732, and an AC magnetic field gradient on the surface of the sample 72 was reflected by a profile measuring device not shown. An alternating current magnetic profile is measured.

A magnetic force microscope (MFM 8) shown in FIG. 2 is known as a technique for measuring direct current magnetic characteristics (direct current magnetic profile) of a magnetic substance sample (see Patent Document 2: WO 2013/047537).
In the MFM 8, the surface of the sample 82 is scanned by a probe tip 811 provided at the tip of the excited probe 81 (cantilever). A coil 84 is provided below the sample 82, and a superimposed magnetic field of a DC magnetic field H_DC generated by the sample 82 and an alternating magnetic field H_AC generated by the coil 84 is applied to the probe tip 811. As the probe tip, mainly a ferromagnetic material having soft magnetic characteristics is used.
The vibration (vibration modulation) of the probe 81 was detected by a vibration detector consisting of a laser (LASER) 831 and a photodiode (PD) 832, and a DC magnetic field gradient on the surface of the sample 82 was reflected by a profile measuring device not shown. A direct current magnetic profile is measured.

A magnetic force microscope (MFM 9) shown in FIG. 3 has been proposed as a technique for measuring direct current magnetic characteristics (direct current magnetic profile) of a magnetic substance sample.
In this MFM 9, a probe comprising a paramagnetic material provided at the tip of an excited probe 91 (cantilever), which has zero coercivity and no hysteresis and which exhibits superparamagnetic material, or a diamagnetic material The needle tip 911 scans the surface of the sample 92. AC magnetic field generating coils 941 and 942 and a DC magnetic field generating coil 943 are provided below the sample 92, and AC magnetic fields H_AC1 and H_AC2 are generated from the AC magnetic field generating coils 941 and 942. An alternating magnetic field H_DC _COIL is generated.
A DC magnetic field H_DC _SMPL generated by the sample 92, H_AC1 and H_AC2 generated by the AC magnetic field generating coils 941 and 942, and H_DC _COIL generated by the DC magnetic field generating coil 943 are applied to the probe tip 911.
In FIG. 3, at the tip of the probe tip, the sum of the magnetic fields of vibrational components of H_AC1 and H_AC2 becomes zero and the magnetic field gradient becomes maximum, and the H_DC _COIL decreases the frequency modulation of the probe 91 To be controlled.
Vibration of the probe 91 is detected by a vibration detector consisting of a laser (LASER) 931 and a photodiode (PD) 932, and a DC magnetic profile reflecting a DC magnetic field on the surface of the sample 92 is measured by a profile measuring device not shown. Be done.

FIG. 4 is an enlarged view of the tip of the probe 71 shown in FIG. 1, the probe 81 shown in FIG. 2, and the probe 91 shown in FIG.
As shown in FIG. 4, the probe tip 711 (811, 911) has a conical shape, and the conical portion is formed by forming a magnetic thin film MM on Si. The magnetic thin film MM is made of a ferromagnetic material (hard magnetic material or soft magnetic material), a paramagnetic material, a material exhibiting superparamagnetism, and a diamagnetic material.
As hard magnetic materials, alloys of Pt and Fe or Co, FeN dB-based intermetallic compounds, SmCo-based intermetallic compounds, etc. are known. As soft magnetic materials, permalloy (Ni-Fe), Co-Zr-Nb, Fe-Co-B, Fe-Co, etc. are known. As materials exhibiting superparamagnetism, granular alloys are known which have a structure in which fine particles of Fe, Co or the like having a particle diameter of about several tens of nm do not contact each other and are surrounded by a nonmagnetic material.

In the present specification, a probe in which a hard magnetic material (ferromagnetic material having a large coercive force or residual magnetization) is used as a magnetic material formed in a conical portion of a probe tip is referred to as a hard magnetic probe, A probe in which a soft magnetic material (a magnetic substance having a small coercive force or residual magnetization and a large magnetic susceptibility) is used as a magnetic body formed in the conical portion is called a soft magnetic probe and is formed in the conical portion A probe in which a paramagnetic substance or a material exhibiting superparamagnetism (with no coercivity or remanent magnetization and no magnetization hysteresis) is used as a magnetic substance is called a paramagnetic probe or a superparamagnetic probe, A probe using a diamagnetic body (magnetization occurs in the reverse direction of the magnetic field, coercivity and residual magnetization are zero, and magnetization has no hysteresis) as a magnetic body formed in the pyramidal part is diamagnetic It is called a probe.
In the MFM 7 of FIG. 1, a hard magnetic probe is mainly used.
A soft magnetic probe is mainly used in the MFM 8 of FIG.
In the MFM 9 of FIG. 3, a paramagnetic probe or a superparamagnetic probe is mainly used.

WO 2013/047538 WO 2013/047537

FIG. 5 shows a typical example of the M-H curve (magnetization-magnetic field characteristic) of a hard magnetic material in which the coercivity is not zero, the magnetization exhibits hysteresis, and the residual magnetization is large.
In FIG. 5, an alternating magnetic field H and a magnetization M that changes in alternating current are described.
The hard magnetic probe preferably has a characteristic such that the magnetization of the probe does not change from the value of the residual magnetization after magnetization when an alternating magnetic field H is applied. FIG. 5 shows the relationship between the alternating magnetic field H and the magnetization M when the coercivity of the hard probe is larger than the strength of the alternating magnetic field H.
In the MFM 7 of FIG. 1, the alternating magnetic field H is a magnetic field generated by the sample 72.
In the MFM 7 of FIG. 1, the probe 71 preferably has a coercivity as high as possible and a high square ratio so that the AC magnetic field H does not change the magnetization of the hard magnetic probe.
When the probe 81 is a soft magnetic probe in the MFM 8 of FIG. 2, the soft magnetic probe 81 operates in a small magnetic field H region so that the AC magnetic field H does not disturb the sample 82 generating a DC magnetic field. It is preferable to have the characteristic that a large change in magnetization M can be obtained without saturation.

6A and 6B show typical examples of the M-H curve (magnetization-magnetic field characteristic) of the soft magnetic material.
In FIGS. 6 (A) and 6 (B), an alternating magnetic field H and a magnetization M that changes in alternating current are described. In FIG. 2, a DC magnetic field H_DC _SMPL generated by a sample is superimposed on an AC magnetic field H_AC.
Even _when a DC magnetic field H_DC _SMPL from a sample is applied, the soft magnetic probe is largely changed by the application of an AC magnetic field H_AC without saturation of the magnetization M of the probe, as shown in, for example, FIG. Need to have the following characteristics:
As shown in FIG. 6B, _when the magnetization M of the probe is saturated by the application of the DC magnetic field H_DC _SMPL from the sample, the magnetization M of the probe does not change even when the AC magnetic field H_AC is applied, and the measurement become unable.
The characteristic of the soft magnetic probe is that the magnetization M of the probe is not saturated and the measurement sensitivity is high (in weak AC magnetic field strength) within the range of the intensity change of the DC magnetic field H_DC _SMPL generated from the sample to be measured It is preferable that a large change in magnetization be obtained).
In the MFM 8 of FIG. 2, when the probe 81 is a soft magnetic probe, the soft magnetic probe has a high magnetic field strength even if the magnetic field strength is small so that the AC magnetic field H does not disturb the sample 82 generating the DC magnetic field. It is necessary to be able to obtain magnetization and to be able to operate in a region where the magnetic field H is not saturated.

FIG. 7 shows a typical example of the M-H curve of a material exhibiting paramagnetic substances or superparamagnetic properties.
In FIG. 7, an alternating magnetic field H and a magnetization M that changes in alternating current are described. The paramagnetic probe preferably has a large magnetic susceptibility (slope of the magnetization M with respect to the magnetic field H).
In the MFM 9 of FIG. 3, when the probe 91 is a paramagnetic probe or a superparamagnetic probe, when the magnetic susceptibility is large, a large magnetization change can be obtained even with the same magnetic field strength.

Probes used for MFM (soft magnetic probe, hard magnetic probe, paramagnetic probe, super paramagnetic probe) are expendables so that the properties will be adapted to the application when the probe is shipped. It is necessary to characterize and keep the quality constant (so that it can work properly with the MFM used).
However, conventionally, a technique for quantitatively evaluating the performance of a magnetic probe has not been provided, and a technique for helping to standardize the performance of a magnetic probe has not been provided.
A first object of the present invention is to provide an evaluation technique capable of evaluating the characteristics of a probe used in MFM, and further to provide a standard of the evaluation technique.

21A and 21B show typical examples of the M-H curve (magnetization-magnetic field characteristic) of the soft magnetic material.
In FIGS. 21 (A) and 21 (B), the range of the horizontal axis is enlarged for convenience of explanation (the gradient of the magnetization curve is shown to be small).
21A and 21B also show the combined magnetic field of the direct current magnetic field H_DC and the alternating current magnetic field H_AC, and the magnetization M.
For example, as shown in FIG. 21A, _when the intensity of the DC magnetic field H_DC _SMPL generated by the sample 82 is small (in FIG. 21A, when H_DC _SMPL is zero), the superimposed magnetic field H_DC _SMPL / AC is Since the magnetization M changes in the linear region of the characteristic curve, the magnetization M is not affected by the saturation region.
However, as shown in FIG. 21B, _when the intensity of the DC magnetic field H_DC _SMPL generated by the sample 82 can not be ignored, the superimposed magnetic field H_DC _SMPL / AC changes in the non-linear region of the characteristic curve. Under the influence of the saturation region, the change width of the magnetization M decreases.
As a result, the MFM 8 suffers from the problem of reduced measurement sensitivity.

  A second object of the present invention is to provide a magnetic force microscope for measuring a DC magnetic field and a method of adjusting a control magnetic field for the magnetic force microscope, which can measure even if the DC magnetic field generated by the sample is large. .

The present invention includes the following forms (1) to (18).
(1)
An apparatus used for characterizing a probe for a magnetic force microscope for measuring a direct current magnetic field or an alternating current magnetic field generated from a sample, comprising:
A probe excitation unit for exciting a probe to be evaluated;
An alternating magnetic field generation unit that generates an alternating magnetic field and applies the alternating magnetic field to the probe;
An AC magnetic field control unit that controls the AC magnetic field generation unit so that the strength of the AC magnetic field changes;
A probe vibration detection unit that detects a vibration of a probe and generates a vibration detection signal;
A spectrum measurement unit that acquires a vibration detection signal generated by the probe vibration detection unit and measures a spectrum of the vibration detection signal corresponding to the strength of the alternating magnetic field;
Extract the second-order sideband intensity (SBI _2nd ) appearing in the spectrum measured by the spectrum measurement unit, or the first-order and second-order sideband intensities appearing in the spectrum measured by the spectrum measurement unit (SBI SBI (Side Band Intensity) extraction unit for extracting _1st and SBI _2nd ),
An SBI change measurement unit that measures a change in the intensity of the side band extracted by the SBI extraction unit with respect to the intensity of the alternating magnetic field;
An evaluation device for a probe for a magnetic force microscope, comprising: an evaluation result output unit that evaluates a characteristic of a probe based on the change measured by the SBI change measurement unit.

(2)
The evaluation apparatus according to (1), wherein
An evaluation device for a probe for a magnetic force microscope, wherein the probe tip of the probe comprises a ferromagnetic material, a paramagnetic material, a superparamagnetic material or a diamagnetic material.

(3)
The evaluation apparatus according to (1), wherein the probe tip of the probe comprises a hard magnetic material of the ferromagnetic material,
The SBI extraction unit extracts the intensities of the first and second sidebands (SBI _1st , SBI _2nd ),
The evaluation result output unit
When the intensity of the alternating magnetic field is increased, the higher the first-order sideband intensity (SBI _1st ), the higher the evaluation result is output, and
An evaluation device for a probe for a magnetic force microscope, which outputs a lower evaluation result as the second-order sideband strength (SBI _2nd ) increases when the strength of the alternating magnetic field is increased.

(4)
The evaluation apparatus according to (1), wherein the probe tip of the probe comprises a soft magnetic material of the ferromagnetic material,
The evaluation result output unit
SBI change transition point detection unit that detects, as a transition point, an AC magnetic field intensity at which a change of the intensity of the secondary sideband measured by the SBI change measurement unit with respect to the AC magnetic field intensity changes from a quadratic function change to a linear function change When,
Probe saturation magnetization characteristic detection unit that acquires the intensity (SBI _2nd ) of the secondary sideband at the transition point, and detects the saturation magnetization of the probe and the intensity of the AC magnetic field when the magnetization of the probe is saturated And an evaluation device for a probe for a magnetic force microscope.

(5)
The evaluation apparatus according to (1), wherein the probe tip of the probe comprises a paramagnetic or diamagnetic substance, or a material exhibiting superparamagnetism,
Evaluation result output unit is an evaluation device for a probe for a magnetic force microscope, which outputs a higher evaluation result as the intensity of a secondary magnetic field increases when the intensity of an alternating magnetic field is increased.

(6)
A method applied to the characterization of a magnetic force microscope probe for measuring a direct current magnetic field or an alternating current magnetic field generated from a sample,
A probe excitation step for exciting the probe;
An alternating magnetic field generation step of generating an alternating magnetic field and applying the alternating magnetic field to the probe;
An AC magnetic field control step of controlling the AC magnetic field such that the intensity of the AC magnetic field generated in the AC magnetic field generating step is changed;
A probe vibration detection step of detecting vibration of a probe and generating a vibration detection signal;
A spectrum measurement step of acquiring a vibration detection signal generated in the probe vibration detection step and measuring a spectrum of the vibration detection signal corresponding to the strength of the alternating magnetic field;
Extract the second-order sideband intensity (SBI _2nd ) appearing in the spectrum measured in the spectrum measurement step, or the first- and second-order sideband intensities appearing in the spectrum measured in the spectrum measurement step (SBI SBI extraction step of extracting _1st , SBI _2nd ),
An SBI change measurement step of measuring a change of the intensity of the sideband extracted in the SBI extraction step with respect to the intensity of the alternating magnetic field;
An evaluation method of a probe for a magnetic force microscope, comprising: an evaluation result output step of evaluating a characteristic of the probe based on the change measured in the SBI change measurement step.

(7)
It is an evaluation method as described in (6),
A method for evaluating a probe for a magnetic force microscope, wherein the probe tip of the probe comprises a ferromagnetic material, a paramagnetic material, a material exhibiting superparamagnetism, or a diamagnetic material.

(8)
The evaluation method according to (6), wherein the probe tip of the probe comprises a hard magnetic material of the ferromagnetic material,
In the SBI extraction step, the intensities of the primary and secondary sidebands (SBI _1st , SBI _2nd ) are extracted,
In the evaluation result output step,
When the intensity of the alternating magnetic field is increased, the higher the first-order sideband intensity (SBI _1st ), the higher the evaluation result is output, and
An evaluation method of a probe for a magnetic force microscope, which outputs a lower evaluation result as the second-order sideband strength (SBI _2nd ) is higher when the strength of the alternating magnetic field is increased.

(9)
(6) The evaluation method according to (6), wherein the probe tip of the probe comprises a soft magnetic material among ferromagnetic materials,
The evaluation result output step is
SBI change transition point detection step detects the AC magnetic field intensity at which the change of the intensity of the secondary sideband measured in the SBI change measurement step with respect to the AC magnetic field intensity changes from a quadratic function change to a linear function change as a transition point When,
The transition point detected in the SBI change transition point detection step and the intensity (SBI _2nd ) of the secondary side band at the transition point are acquired, and the saturation magnetization of the probe and the magnetization of the probe are saturated. And a probe saturation magnetization characteristic detecting step of detecting an intensity of an alternating magnetic field, and a method of evaluating a probe for a magnetic force microscope.

(10)
The evaluation method according to (6), wherein the probe tip of the probe comprises a paramagnetic or diamagnetic substance, or a material exhibiting superparamagnetic properties,
In the evaluation result output step, the evaluation method of the probe for a magnetic force microscope, which outputs a higher evaluation result as the intensity of the secondary side band increases when the intensity of the AC magnetic field is increased.

(11)
An AC magnetic field and a control DC magnetic field are applied to the probe being excited, the surface of the sample is scanned by the probe, and the vibration of the probe is detected to measure the DC magnetic field of the surface of the sample A microscope,
A probe provided with a probe tip having a magnetic thin film formed on the tip;
A probe excitation unit for exciting the probe;
A composite magnetic field generation unit that generates a composite magnetic field of an AC magnetic field and a control DC magnetic field;
A magnetic field control unit that performs control to change the strength of the control DC magnetic field, and performs control to fix the strength of the control DC magnetic field and to sequentially change the strength of the AC magnetic field;
A probe vibration detection unit that detects a vibration of a probe and generates a vibration detection signal;
A scanning unit that spatially drives the probe;
A direct current magnetic field characteristic measurement unit that measures a direct current magnetic field of the surface of the sample by acquiring a vibration detection signal detected by the probe vibration detection unit and analyzing modulation generated in the vibration of the probe;
A spectrum measurement unit which acquires a vibration detection signal detected by the probe vibration detection unit and measures a spectrum of the vibration detection signal corresponding to the intensity of the alternating magnetic field;
A magnetization saturation detection unit that detects the intensity of an alternating magnetic field when the magnetization of the magnetic thin film formed on the probe tip is saturated, based on the change in intensity of the side band of the spectrum measured by the spectrum measurement unit;
A magnetic force microscope characterized by comprising.

(12)
(11) The magnetic force microscope according to (11),
The magnetization saturation detection unit
An SBI extraction unit for extracting the intensity of the second-order side band of the spectrum measured by the spectrum measurement unit;
The intensity of the AC magnetic field is changed from a certain value to a predetermined value under the control DC magnetic field set to a certain value within a predetermined range including zero, and the second-order sideband extracted by the SBI extraction unit The presence or absence of a transition from a quadratic function change to a linear function change of the change of the intensity of the alternating magnetic field to the intensity is detected, and when the transition is detected, the intensity of the alternating magnetic field when the transition occurs is measured. SBI change measurement unit,
A magnetic field strength aptitude determining unit which determines the aptitude of the control DC magnetic field strength and / or the ac magnetic field aptitude based on the measurement result by the SBI change measurement part;
A magnetic force microscope characterized by comprising.

(13)
(11) The magnetic force microscope according to (11),
A magnetic force microscope characterized in that a magnetic thin film formed on a probe tip is made of a soft magnetic material.

(14)
(11) The magnetic force microscope according to (11),
A magnetic force microscope, wherein the combined magnetic field generation unit comprises a coil driven by combined current of alternating current and direct current.

(15)
(11) The magnetic force microscope according to (11),
A magnetic force microscope, wherein the synthetic magnetic field generation unit comprises a first coil driven by an alternating current and a second coil driven by a direct current.

(16)
An AC magnetic field and a control DC magnetic field are applied to the probe being excited, the surface of the sample is scanned by the probe, and the vibration of the probe is detected to measure the DC magnetic field of the surface of the sample It is a magnetic field adjustment method for control of a microscope, and
A probe excitation step for exciting the probe;
A control magnetic field generation step of generating a composite magnetic field of an alternating magnetic field and a control DC magnetic field and applying the composite magnetic field to the probe;
A magnetic field control step of performing control to change the strength of the control DC magnetic field, and performing control to fix the strength of the control DC magnetic field and change the strength of the AC magnetic field;
A probe vibration detection step of detecting vibration of a probe and generating a vibration detection signal;
A spectrum measurement step of acquiring a vibration detection signal detected in the probe vibration detection step and measuring a spectrum of the vibration detection signal corresponding to the strength of the alternating magnetic field;
When measuring the direct current magnetic field of the sample, whether or not the magnetization of the magnetic thin film formed on the probe tip provided at the tip of the probe is saturated is the intensity change of the side band of the spectrum measured in the spectrum measurement step. A magnetization saturation detection step of detecting based on
A method of adjusting a control magnetic field of a magnetic force microscope, comprising

(17)
It is a control magnetic field adjustment method as described in (16),
The magnetization saturation detection step
An SBI extraction step of extracting the intensity of the second-order sideband of the spectrum measured in the spectrum measurement step;
The strength of the control DC magnetic field is set to a value in a range including zero, the strength of the AC magnetic field is changed from a certain value to a predetermined value, and the AC magnetic field of the second sideband strength extracted in the SBI extraction step An SBI change measurement step of detecting the presence or absence of a transition from a quadratic function change to a linear function change of the change with respect to the intensity and measuring the intensity of the alternating magnetic field when the transition occurs when the transition is detected; ,
A control magnetic field aptitude determination step of determining the aptitude of the control DC magnetic field strength and / or the ac magnetic field aptitude based on the measurement result in the SBI change measurement step;
A method of adjusting a magnetic field for control of a magnetic force microscope, comprising:

(18)
(16) The magnetic force microscope according to (16),
A method for adjusting a control magnetic field of a magnetic force microscope, wherein a magnetic thin film formed on a probe tip is made of a soft magnetic material.

According to the embodiments (1) to (10), a probe for MFM to which alternating current is applied (specifically, a hard magnetic probe, a soft magnetic probe, a paramagnetic probe, a superparamagnetic probe, During the evaluation of the diamagnetic probe, an alternating magnetic field of which the intensity is changed (usually, stepwise) is applied to the excited probe, and the characteristic of the probe based on the spectrum obtained from the vibration of the probe Can be evaluated.
According to the embodiments (11) to (18), in the magnetic force microscope for detecting the DC magnetic field of the sample (sample DC magnetic field), the soft magnetic probe does not saturate the strength of the control DC magnetic field and / or AC magnetic field It can be adjusted to an appropriate value.

FIG. 1 is a view showing an MFM using a hard magnetic probe for measuring an alternating magnetic field gradient from a sample. FIG. 2 is a diagram showing an MFM using a soft magnetic probe, a paramagnetic probe, or a superparamagnetic probe for measuring a direct current magnetic field gradient from a sample. FIG. 3 is a diagram showing an MFM using a paramagnetic probe or a superparamagnetic probe for measuring an absolute value of a direct current magnetic field from a sample. FIG. 4 is an enlarged explanatory view of the tip of the probe. FIG. 5 is a diagram showing an M-H curve (magnetization-magnetic field characteristic) of a ferromagnetic substance (hard magnetic material). FIG. 6 is a view showing an example of the M-H curve (magnetization-magnetic field characteristic) of the soft magnetic material in the ferromagnetic material. FIG. 7 is a diagram showing a typical example of an M-H curve of a material exhibiting paramagnetic substances or superparamagnetic properties. In this invention, it is a figure which shows the spectrum obtained by changing the magnitude | size of the alternating current magnetic field applied to a probe in steps. FIG. 9 is an explanatory view of an evaluation device of a probe for a magnetic force microscope, for explaining the first embodiment of the present invention. FIG. 10 is a flow chart showing an evaluation procedure when evaluating a probe using the evaluation apparatus shown in FIG. FIG. 11 shows the strength of the AC magnetic field before and after the probe magnetization is saturated, and the strength of the magnetization, as measured while gradually increasing the amplitude of the AC magnetic field for the soft magnetic probe whose probe tip is Ni—Fe. It is a figure which shows a relation. FIG. 12 is an explanatory view of an evaluation device of a probe for a magnetic force microscope, for explaining a second embodiment of the present invention. FIG. 13 is a diagram (1 of a spectrum diagram) illustrating a spectrum of probe vibration measured by the spectrum measurement unit in the second embodiment. FIG. 14 is a diagram (spectrum diagram 2) illustrating a spectrum of probe vibration measured by the spectrum measurement unit in the second embodiment. FIG. 15 is a diagram (3 of a spectrum diagram) illustrating a spectrum of probe vibration measured by the spectrum measurement unit in the second embodiment. FIG. 16 is a flow chart showing an evaluation procedure when evaluating a probe using the evaluation apparatus shown in FIG. FIG. 17 is a graph showing the relationship between the intensity of the alternating magnetic field when the magnetization is saturated measured for the soft magnetic probe and the intensity of the spectrum of the probe vibration measured by the spectrum measurement unit. FIG. 18A is a view showing the relationship between the intensity of the alternating magnetic field when the magnetization is saturated measured for various soft magnetic probes and the intensity of the spectrum of the probe vibration measured by the spectrum measurement unit. . FIG. 18B is a table and a correlation diagram showing the relationship between the intensity of the alternating magnetic field when the magnetization is saturated and the intensity of the magnetization measured for various soft magnetic probes. FIG. 19 is an explanatory view of an evaluation device of a probe for a magnetic force microscope, for explaining a third embodiment of the present invention. FIG. 20 is a flow chart showing an evaluation procedure when evaluating a probe using the evaluation device shown in FIG. FIG. 21 is a diagram showing an M-H curve of the soft magnetic material thin film. FIG. 22 is an explanatory view of a magnetic force microscope, for explaining an embodiment of a magnetic force microscope of the present invention. FIG. 23A is a view showing the relationship between an AC magnetic field, a control DC magnetic field, and a sample DC magnetic field. FIG. 23B is a view showing a synthetic magnetic field generation unit constituted by one coil and a magnetic field control unit used for control thereof. FIG. 24 is a diagram showing a magnetization saturation detection unit configured of an SBI extraction unit, an SBI change measurement unit, and a magnetic field strength suitability determination unit. FIG. 25A is a diagram showing how the intensity characteristics of the secondary side band SBI_2nd change with respect to the change in the intensity of the AC magnetic field H_AC when the intensity of the control DC magnetic field is changed. FIG. 25 (B) is a graph showing a change of the AC magnetic field strength at the transition point of the strength characteristic with respect to the control DC magnetic field strength. FIG. 25C is a graph in which the sum of the AC magnetic field strength at the transition point and the control DC magnetic field strength is plotted against the control DC magnetic field strength. FIG. 26 is a flow chart in the case of carrying out the control magnetic field adjustment method of the present invention using the magnetic force microscope shown in FIG. FIG. 27 is a diagram showing an example in which the magnetization saturation detection step is composed of an SBI extraction step, an SBI change measurement step, and a control magnetic field suitability determination step in the magnetization saturation detection step.

<1. Evaluation apparatus and evaluation method of probe for magnetic force microscope>
<1.1 principle>
A magnetic force microscope (MFM) is a form of noncontact atomic force microscope that detects a force gradient between probe samples generated by bringing an excited probe (cantilever) close to an observation sample.
In a magnetic force microscope, a magnetic substance is used for a probe tip at the tip of a probe (cantilever) to detect a magnetic force gradient acting between an observation sample generating a magnetic field and the probe tip, thereby imaging the magnetic field gradient Microscope.
Here, the vibration direction of the probe is taken as a direction perpendicular to the sample surface, and is referred to as the z direction. When a force F _z ^tip-sample acts between the probe tip and the sample, the spring constant of the probe (cantilever) can be determined by the force gradient 探針 F _z ^tip-sample / ∂z between the probe samples. It changes above. The equation of motion of probe vibration at this time is as follows. Here, the sign of F _z ^tip-sample is positive in the direction of attraction.

ω₀：加振角周波数
ｍ：探針の等価質量
γ：減衰係数
ｋ₀：カンチレバー固有のバネ定数
その結果、探針の共振周波数は、探針試料間に、Ｆ_z ^tip-sampleが働いていない場合のω₀＝（ｋ₀／ｍ）^1/2から変化し、式（２）で表される。

ω ₀ : Excitation angle frequency m: Equivalent mass of probe γ: Attenuation coefficient k ₀ : Spring constant specific to the cantilever As a result, the resonance frequency of the probe is such that F _z ^tip-sample works between the probe samples _{ω 0 = (k 0 / m} ) varies from ^1/2 of the absence, of the formula (2).

Ｆ_z ^tip-sample：探針−試料間に働く力
ｋ₀：探針のバネ定数
ω₀：試料からの力が探針に働く前の探針の励振角周波数
ｍ：探針の等価質量
磁気力顕微鏡では、バネ定数ｋの実効的な変化Δｋは、探針が双磁極探針および単磁極探針として振る舞う場合、式（３）で表される。

F _z ^tip-sample : Force acting between the probe and the sample k ₀ : Spring constant of the probe ω ₀ : Excitation angular frequency of the probe before the force from the sample acts on the probe m: Equivalent mass of the probe Magnetism In a force microscope, the effective change Δk of the spring constant k is expressed by Equation (3) when the probe behaves as a double pole probe and a single pole probe.

磁気力顕微鏡の高分解能化には、探針−試料間距離の低減が効果的である。探針−探針間距離を低減した場合には、探針の磁気モーメント長と比較して、探針−試料間距離が小さくなることにより、探針先端の磁極の寄与が主となるので、探針は単磁極探針として振る舞うことになる。
単磁極探針において、探針に直流磁場Ｈ_z ^dcおよび交流磁場Ｈ_z ^ac＝Ｈ_z0 ^acｃｏｓ（ω_mｔ）を印加した場合の、Δｋの一般式は、探針磁化の磁場に対する非線形性を考慮すると、式（４）で表される。

In order to increase the resolution of the magnetic force microscope, it is effective to reduce the distance between the probe and the sample. When the distance between the probe and the probe is reduced, the distance between the probe and the sample is smaller than the magnetic moment length of the probe, so that the magnetic pole at the tip of the probe mainly contributes. The probe will behave as a single pole probe.
In the case of applying a direct current magnetic field H _z ^dc and an alternating current magnetic field H _z ^ac = H _{z 0} ^ac cos (ω _m t) to the probe in a single-pole probe, the general formula of Δk is nonlinearity to the magnetic field of the probe magnetization In consideration of, it is represented by Formula (4).

ｑ^dc：探針先端の時間変化しない直流磁極
ｑ_Nω_m ^ac：探針先端の角周波数Ｎωmで時間変化する交流磁極
Ｈ_z ^dc：探針先端での試料面に垂直方向（ｚ方向）の直流磁場
Ｈ_z0 ^ac：探針先端での試料面に垂直方向（ｚ方向）の交流磁場の振幅
ここで、交流磁場の角周波数ωmが探針の共振周波数と異なる、非共振周波数である場合には、バネ定数の見掛け上の周期的変化項は、探針振動に周波数変調現象を引き起こすことが知られている。バネ定数の見掛け上の周期的変化項の非共振角周波数をωとおくと、探針振動の運動方程式は以下となる。

q ^dc : DC magnetic pole not changing with time of probe tip q _N ω _m ^ac : AC magnetic pole changing with time at angular frequency _N ωm of probe tip H _z ^dc : Direction perpendicular to the sample surface at the probe tip (z direction) DC magnetic field H _{z 0} ^ac : Amplitude of AC magnetic field in the direction perpendicular to the sample surface at the tip of the probe (z direction) where the angular frequency _{ω m} of the AC magnetic field is non-resonant frequency different from the resonant frequency of the probe It is known that an apparent periodic change term of a spring constant causes a frequency modulation phenomenon to probe vibration. Assuming that the non-resonant angular frequency of the apparent periodic change term of the spring constant is ω, the equation of motion of the probe vibration is as follows.

ω₀：加振角周波数
ω：交流磁場の角周波数
ｍ：ソフト磁性探針（探針チップ８１１）の等価質量
γ：減衰係数
ｋ₀：カンチレバー（探針部材８１）固有のバネ定数
Δｋ₀：カンチレバー（探針部材８１）のバネ定数のみかけ上の周期的変化の振幅
この解は、次式で表される。

ω ₀ : Excitation angular frequency ω: Angular frequency of alternating magnetic field m: Equivalent mass of soft magnetic probe (probe tip 811) γ: Attenuation coefficient k ₀ : Spring constant specific to cantilever (probe member 81) Δk ₀ : Amplitude of apparent periodic change in spring constant of cantilever (probe member 81) This solution is expressed by the following equation.

バネ定数が実効的に種々の非共振周波数で周期的に変化する場合には、探針振動にこれらの非共振周波数による周波数変調成分が加わることになる。
以下では、種々の典型的な磁性探針について、直流磁場Ｈ_z ^dcおよび交流磁場Ｈ_z ^ac＝Ｈ_z0 ^acｃｏｓ（ω_mｔ）を印加した場合の実効的バネ定数の変化を説明する。

When the spring constant effectively changes periodically at various non-resonant frequencies, frequency modulation components due to these non-resonant frequencies are added to the probe vibration.
Hereinafter, various exemplary magnetic probe, illustrating the change in the DC magnetic field H _z ^dc and ac magnetic field ^{_{H z ac = H z0 ac cos}} (ω m t) effective spring constant in the case of applying the.

First, the case of a hard magnetic probe will be described. If the hard magnetic probe has ideal hard magnetic characteristics, the magnetization of the probe does not change even when an AC magnetic field is applied, and therefore, the AC magnetic pole q ^ac does not occur at the tip. As a result, Δk is expressed by the following equation.

したがって、Δｋは、交流磁場の角周波数ω_mと等しい周波数成分のみとなり、探針振動にω_m成分のみの周波数変調が発生する。
ハード磁性探針のハード磁気特性が十分でない場合には、交流磁場の印加により探針先端に時間変化する交流磁極ｑ^acが発生するので、Δｋは、次式で表される。

Therefore, Δk has only a frequency component equal to the angular frequency ω _m of the AC magnetic field, and frequency modulation of only the ω _m component occurs in the probe vibration.
When the hard magnetic properties of the hard magnetic probe are not sufficient, an alternating current magnetic field q ^ac which changes with time is generated at the tip of the probe by the application of an alternating magnetic field, and Δk is expressed by the following equation.

したがって、Δｋには、交流磁場の角周波数ω_mと等しい周波数成分の他に、新たに２ω_mを主とする高次の周波数成分が発生する。すなわち、２ω_m成分による探針振動の周波数変調の有無により、ハード磁性探針の性能を判断することが可能になる。

Therefore, in addition to the frequency component equal to the angular frequency ω _m of the AC magnetic field, a high-order frequency component mainly having 2ω _m is generated in Δk. That is, the performance of the hard magnetic probe can be determined by the presence or absence of frequency modulation of the probe vibration by the 2ω _m component.

Next, the case of a paramagnetic probe will be described. In a paramagnetic probe, the magnetization is proportional to the magnetic field and does not show saturation at a magnetic field strength that can be generated by an electromagnet. In addition, the paramagnetic probe has no residual magnetization and has a coercivity of zero. When a direct current magnetic field H _z ^dc and an alternating current magnetic field H _z ^ac = H _{z 0} ^ac cos (ω _m t) are applied, the time-varying alternating current magnetic pole of the probe tip changes approximately linearly with the alternating current magnetic field. The general formula is represented by the following formula.

Δｋは、交流磁場Ｈ_z ^ac＝Ｈ_z0 ^acｃｏｓ（ω_mｔ）のみを印加した場合、次式で表される。

When only an alternating magnetic field H _z ^ac = H _{z 0} ^ac cos (ω _m t) is applied, _{Δ k} is expressed by the following equation.

２ω_mで変化する探針振動の周波数変調成分の大きさから、測定感度の程度を評価することが可能となる。
常磁性探針に関する上記の議論は、反磁性探針および超常磁性探針についてもあてはまる。

The degree of measurement sensitivity can be evaluated from the magnitude of the frequency modulation component of the probe vibration that changes at 2ω _m .
The above discussion of paramagnetic probes also applies to diamagnetic and superparamagnetic probes.

Next, the case of the soft magnetic probe will be described. The magnetization of the soft magnetic probe changes non-linearly with the magnetic field and saturates as the magnetic field increases. When a direct current magnetic field H ^dc and an alternating current magnetic field H _z ^ac = H _{z 0} ^ac cos (ω _m t) are applied, Δk is expressed by the following equation.

Δｋは、交流磁場Ｈ_z ^ac＝Ｈ_z0 ^acｃｏｓ（ω_mｔ）のみを印加した場合、次式で表される。

When only an alternating magnetic field H _z ^ac = H _{z 0} ^ac cos (ω _m t) is applied, _{Δ k} is expressed by the following equation.

ここで、交流磁場の強度Ｈ_z0 ^acが小さな場合には、探針磁化はほぼ交流磁場に比例して変化するので、Δｋは、次式で表される。

Here, when the intensity H _z0 ^ac of the alternating magnetic field is small, the probe magnetization changes substantially in proportion to the alternating magnetic field, so Δk is expressed by the following equation.

したがって、Δｋの２ω_m成分は以下となる。

Thus, the 2ω _m component of Δk is

ここでｑ_ωm ^acはＨ_z0 ^acにほぼ比例して変化する（ｑ_ωm ^ac＝αＨ_z0 ^ac）ので、Δｋ（２ω_mｔ）はＨ_z0 ^acの２乗に比例して変化することになる。

Here q _.omega.m ^ac since changes substantially in proportion to ^{_{H z0 ac (q ωm ac =}} αH z0 ac), Δk (2ω m t) will vary in proportion to the square of H _z0 ^ac.

交流磁場の強度Ｈ_z0 ^acが大きくなると、ｑ^acは飽和する。磁化曲線が角形で磁場方向が正の場合には、探針磁化がＭ_s、負の場合には、探針磁化が−Ｍ_sとなる、Ｈ_z0 ^acが探針の保磁力に比較して非常に大きな場合には、探針磁化ｍ_z ^tipは矩形状に時間変化し以下で表される。

As the strength H _z0 ^ac of the alternating magnetic field increases, q ^ac saturates. When the magnetization curve is square and the magnetic field direction is positive, the probe magnetization is M _s , and when the magnetization curve is negative, the probe magnetization is −M _s , H _z0 ^ac is compared with the coercivity of the probe When it is very large, the probe magnetization m _z ^tip changes with time in a rectangular shape and is expressed by the following.

したがって、ｑ_ωm ^acの時間変化は以下で表される。

Therefore, the time change of q _ωm ^ac is expressed by the following.

ｑ_s：探針先端の磁極の飽和値
このとき、Δｋは、次式で表される。

q _s : Saturation value of magnetic pole at tip of probe At this time, Δk is expressed by the following equation.

このとき、Δｋ（２ω_mｔ）は、次式で表され、Ｈ_z0 ^acの１乗に比例して変化する。

At this time, Δk (2ω _m t) is expressed by the following equation, and changes in proportion to the first power of H _z0 ^ac .

したがって、Δｋ（２ω_mｔ）は、Ｈ_z0 ^acの増加に伴い、最初はＨ_z0 ^acの２乗に比例して変化し、さらにＨ_z0 ^acが増加して探針磁化が飽和に達すると、Ｈ_z0 ^acの１乗に比例して変化するようになる。ここで、Δｋ（２ω_mｔ）のＨ_z0 ^ac依存性が２次から１次に変化するＨ_z0 ^acが、探針磁化を飽和させる交流磁場強度になる。
一方、観察試料から探針に直流磁場Ｈ_z ^dcが加わった際のΔｋは、次式で表される。

Therefore, Δk (2ω _m t) is with increasing H _z0 ^ac, the first change in proportion to the square of H _z0 ^ac, probe magnetization reaches saturation increases more H _z0 ^ac, It changes in proportion to the first power of H _z0 ^ac . Here, Δk (2ω _m t) of H _z0 ^ac dependence then changed from 1 to 2 primary H _z0 ^ac becomes the alternating magnetic field intensity to saturate the probe magnetization.
On the other hand, Δk when a direct current magnetic field H _z ^dc is applied from the observation sample to the probe is expressed by the following equation.

したがって、Δｋ（ω_mｔ）は以下のように与えられる。

Therefore, Δk (ω _m t) is given as follows.

したがって、観察試料からの直流磁場勾配∂Ｈ_z ^dc／∂ｚの最大計測感度を、探針磁化が飽和に達した際の、探針先端の磁極の大きさに比例するΔｋ（２ω_mｔ）の大きさから、評価することが可能なことがわかる。
したがって、種々の磁性探針を加振し、同時に探針の共振周波数と異なる周波数（非共振周波数）の交流磁場Ｈ_z ^ac＝Ｈ_z0 ^acｃｏｓ（ω_mｔ）を磁性探針に印加し、その際に発生する、周波数変調による振動スペクトルの次数およびこれら振動スペクトルのＨ_z0 ^acの強度に対する依存性を解析することで、磁性探針の性能を評価することができる。

Therefore, the maximum measurement sensitivity of the direct current magnetic field gradient ∂H _z ^dc / ∂z from the observation sample is Δk (2ω _m t) proportional to the size of the magnetic pole of the probe tip when the probe magnetization reaches saturation. From the size of, it is understood that it is possible to evaluate.
Therefore, various magnetic probes are oscillated, and simultaneously an alternating magnetic field H _z ^ac = H _{z 0} ^ac cos (ω _m t) having a frequency (non-resonance frequency) different from the resonance frequency of the probes is applied to the magnetic probes The performance of the magnetic probe can be evaluated by analyzing the order of the vibration spectrum by frequency modulation and the dependence of the vibration spectrum on the intensity of H _{z 0} ^ac generated at that time.

In the present invention, in order to evaluate the performance of the magnetic probe, the spectrum of the vibration of the probe is observed.
By _changing the magnitude of the alternating current magnetic field amplitude H _z0 ^ac stepwise, a spectrum as shown in FIG. 8 is obtained.
As shown in FIG. 8, qualitatively, the increase in the intensity of the second sideband is slowed, and when the intensity of the third or higher sidebands sharply increases, the magnetization of the probe reaches saturation. It is.
The above-described method of detecting the saturation of magnetization can also be applied when the probe is a hard magnetic probe, or a paramagnetic probe, a superparamagnetic probe, or a diamagnetic probe.

<1.2 Evaluation Device for Magnetic Force Microscope Probe (1)>
FIG. 9 is an explanatory view showing a first embodiment of an evaluation device of a probe for a magnetic force microscope of the present invention.
In FIG. 9, a hard magnetic probe PRB is used as a probe.
In FIG. 9, the evaluation device 11 includes a probe excitation unit 111, an AC magnetic field generation unit 112, an AC magnetic field control unit 113, a probe vibration detection unit 114, a spectrum measurement unit (spectrum analyzer) 115, an SBI extraction unit 116, and SBI change. A measurement unit 117 and an evaluation result output unit 119 are provided.

The hard magnetic probe PRB is a cantilever made of silicon, and in FIG. 9, a probe tip TIP whose surface is formed of a hard magnetic thin film is formed on the lower surface of the tip of the hard magnetic probe PRB.
The probe excitation unit 111 can excite the hard magnetic probe PRB to be evaluated. In FIG. 9, the probe excitation unit 111 includes an AC power supply 1111 and a piezoelectric element 1112.
In FIG. 9, the AC magnetic field generation unit 112 is an AC coil.

AC magnetic field control unit 113 controls AC magnetic field generation unit 112 such that strength Hi of AC magnetic field H_AC changes stepwise (step change).
The probe vibration detection unit 114 detects the vibration of the hard magnetic probe PRB and generates a vibration detection signal VIB. The probe vibration detection unit 114 includes a laser (LSR) 1141 and a photo detector (PD) 1142. A reflecting mirror is formed on the top end of the hard magnetic probe PRB. The laser beam LB emitted from the LSR 1141 is reflected by the top end of the hard magnetic probe PRB and is incident on the PD 1142.

The spectrum measurement unit 115 acquires the vibration detection signal OSC detected by the probe vibration detection unit 114, and measures the spectrum of the vibration detection signal OSC corresponding to the intensity Hi of the alternating magnetic field H_AC.
The SBI extraction unit 116 extracts the intensities SBI _1st and SBI _2nd of the primary and secondary sidebands appearing in the spectrum measured by the spectrum measurement unit 115 (see FIG. 8).

The SBI change measurement unit 117 measures a change in the intensity (SBI _1st , SBI _2nd ) of the side band extracted by the SBI extraction unit 116 with respect to the intensity Hi of the alternating magnetic field H_AC.

The evaluation result output unit 119 evaluates the characteristics of the hard magnetic probe PRB based on the change in the sideband intensity (SBI _1st , SBI _2nd ) relative to the intensity Hi of the AC magnetic field H_AC measured by the SBI change measurement unit 117. Output the result ES.
The evaluation result output unit 119 outputs a higher evaluation result ES as the strength SBI _1st of the primary side band SB_1st increases when the AC magnetic field control unit 113 increases the strength of the AC magnetic field H_AC.
In addition, the evaluation result output unit 119 outputs a lower evaluation result ES as the intensity SBI _2nd of the second side band SB_2nd increases when the alternating current magnetic field control unit 113 increases the intensity of the alternating magnetic field H_AC.
There is no particular limitation on the method of determining the evaluation result ES based on the change in the primary and secondary sideband intensities (SBI _1st , SBI _2nd ) with respect to the intensity Hi of the alternating magnetic field H_AC. but, for example, a first function f ₁ that increases monotonically with increasing intensity SBI _1st of first-order sideband and _{(SBI 1st),} monotonically with increasing intensity SBI _2nd secondary sidebands It can be performed by an evaluation function F (SBI _1st , SBI _2nd ) = f ₁ (SBI _1st ) + f ₂ (SBI _2nd ) which is a sum of the second function f ₂ (SBI _2nd ) to be decreased. As the values of the sideband intensities (SBI _1st , SBI _2nd ) used by the evaluation result output unit 119 to determine the evaluation result ES, for example, the intensity Hi of the alternating magnetic field H_AC can be generated from the alternating magnetic field generation unit 112 The value of the sideband strength (SBI _1st , SBI _2nd ) at the maximum strength can be preferably adopted.
<1.3 Evaluation method of probe for magnetic force microscope (1)>

FIG. 10 is a flow chart showing an evaluation procedure when evaluating the hard magnetic probe PRB using the evaluation device 11 of FIG.
Probe Magnetizing Step S100: The hard magnetic probe PRB is magnetized. In order to magnetize the hard magnetic probe PRB, for example, an apparatus such as an electromagnet, a pulse magnet, or a superconducting magnet can be used.
Probe Mounting Step S101: The hard magnetic probe PRB is mounted on a probe holder not shown in FIG.
Probe Excitation Step S102: The hard magnetic probe PRB to be evaluated is excited.

AC Magnetic Field Generation Step S103: AC magnetic field H_AC is generated, and AC magnetic field H_AC is applied to the hard magnetic probe PRB.
AC Magnetic Field Control Step S104: The AC magnetic field H_AC is controlled so that the intensity Hi of the AC magnetic field H_AC generated in the AC magnetic field generation step S103 changes.

Probe Vibration Detection Step S105: The vibration of the hard magnetic probe PRB is detected to generate a vibration detection signal VIB.
Spectrum Measurement Step S106: The vibration detection signal VIB generated in the probe vibration detection step S105 is acquired, and the spectrum of the vibration detection signal corresponding to the intensity Hi of the AC magnetic field H_AC is measured.

SBI extraction step S107: intensity SBI _1st of primary and secondary sidebands appear in the measured spectrum in spectral measurement step S106, extracts the SBI _2nd.
SBI change measuring step S108: the intensity of the sidebands extracted in SBI extraction step S107 in (SBI _1st, SBI _2nd), measuring the change with respect to strength Hi of the alternating magnetic field H_AC.

Evaluation Result Output Step S110: The characteristics of the hard magnetic probe PRB are evaluated based on the change of the sideband intensity (SBI _1st , SBI _2nd ) relative to the intensity Hi of the alternating magnetic field H_AC measured in the SBI change measurement step S108. . Here, when the strength Hi of the AC magnetic field H_AC is increased in the AC magnetic field control step S104, the higher the strength SBI _{1st of the} primary side band SB_1st is, the higher the evaluation result ES is output (step S110A). Further, when the intensity Hi of the alternating magnetic field H_AC is increased in the alternating magnetic field control step S104, the lower the evaluation result ES is output as the intensity (SBI _2nd ) of the secondary side band SB_2nd becomes higher (step S110B).
There is no particular limitation on the method of determining the evaluation result ES based on the change in the primary and secondary sideband intensities (SBI _1st , SBI _2nd ) with respect to the intensity Hi of the alternating magnetic field H_AC in the evaluation result output step S110. but, for example, a first function f ₁ that increases monotonically with increasing intensity SBI _1st of first-order sideband and _{(SBI 1st),} monotonically with increasing intensity SBI _2nd secondary sidebands It can be performed by an evaluation function F (SBI _1st , SBI _2nd ) = f ₁ (SBI _1st ) + f ₂ (SBI _2nd ) which is a sum of the second function f ₂ (SBI _2nd ) to be decreased. As the value of the sideband strength (SBI _1st , SBI _2nd ) used in the evaluation result output step S110 to determine the evaluation result ES, for example, the magnitude Hi of the alternating magnetic field H_AC can be generated in the alternating magnetic field generation step S103. The value of the sideband strength (SBI _1st , SBI _2nd ) at the maximum strength can be preferably adopted.

<1.4 Evaluation Device for Probe for Magnetic Force Microscope (2)>
FIG. 12 is an explanatory view showing a second embodiment of the evaluation device for a probe for a magnetic force microscope of the present invention.
In FIG. 12, a soft magnetic probe PRB is used as a probe.
12, the evaluation device 21 includes a probe excitation unit 211, an AC magnetic field generation unit 212, an AC magnetic field control unit 213, a probe vibration detection unit 214, a spectrum measurement unit (spectrum analyzer) 215, an SBI extraction unit 216, and SBI change. The measurement unit 217, the SBI change transition point detection unit 218, and the probe saturation magnetization characteristic detection unit 219 are provided.

  The probe PRB is a cantilever made of silicon, and in FIG. 12, a probe tip TIP whose surface is formed of a soft magnetic thin film is formed on the lower surface of the tip of the probe PRB.

  The configurations of the probe excitation unit 211, AC magnetic field generation unit 212, AC magnetic field control unit 213, probe vibration detection unit 214, spectrum measurement unit (spectrum analyzer) 215, SBI extraction unit 216, and SBI change measurement unit 217 are shown in FIG. In the evaluation apparatus 11 of 9 (first embodiment), the probe excitation unit 111, AC magnetic field generation unit 112, AC magnetic field control unit 113, probe vibration detection unit 114, spectrum measurement unit (spectrum analyzer) 115, SBI extraction unit 116 and the configuration of the SBI change measurement unit 117.

  The spectrum measurement unit 215 acquires the vibration detection signal OSC detected by the probe vibration detection unit 214, and measures the spectrum of the vibration detection signal OSC corresponding to the intensity Hi of the alternating magnetic field H_AC. An example of the measured spectrum is shown in FIG. 13, FIG. 14 and FIG.

The SBI extraction unit 216 extracts the intensities SBI _1st and SBI _2nd of the primary and secondary sidebands that appear in the spectrum measured by the spectrum measurement unit 215 (a primary sideband SB_1st and a secondary sideband For SB_2nd, refer to FIG. 13, FIG. 14 and FIG.

The SBI change transition point detection unit 218 acquires information related to the change with respect to the alternating current magnetic field strength Hi of the secondary side band intensity (SBI _2nd ) measured by the SBI change measurement unit 217, and the secondary side band AC magnetic field intensity Hi in which the relationship between the intensity SBI _2nd and the intensity Hi of the AC magnetic field H_AC is changed, that is, the relationship in which the secondary sideband intensity SBI _2nd is proportional to the square of the intensity Hi of the AC magnetic field An alternating current magnetic field intensity Hi is detected as a transition point T_PNT in which the intensity SBI _2nd of the secondary sideband changes in a relationship proportional to the first power of the intensity Hi of the alternating current magnetic field.
As an example, a graph in which the relationship between the intensity of the alternating magnetic field and the intensity of the second-order side band is measured using a double-logarithmic plot measured on a soft magnetic probe having a magnetic film made of Ni-Fe on the surface is shown. It is shown in FIG.

The method of detecting the transition point T_PNT is not particularly limited. For example, in a graph in which the intensity SBI _2nd of the second side band is plotted logarithmically with respect to the alternating current magnetic field intensity Hi, the alternating current magnetic field intensity Hi is relative The first regression line for lower data points and the data point group for which the alternating magnetic field strength Hi is relatively high (ie, the alternating magnetic field strength Hi is higher than the data points regressed by the first regression line) Calculating a second regression line having a slope different from the first regression line (usually smaller than the first regression line), and a point of intersection between the first regression line and the second regression line The intersection point can be detected as the transition point T_PNT by performing the step of calculating For the calculation of the first regression line and the second regression line, for example, a known optimization method such as the least squares method can be employed. The method of identifying the data point group to be regressed by the first regression line and the data point group to be regressed by the second regression line is not particularly limited. The groups may be separated, or, for example, N data points (x _i , y _i ) where x is the logarithm of alternating magnetic field strength Hi and y is the logarithm of secondary sideband intensity SBI _2nd. N is an integer greater than or equal to 4; x ₁ <x ₂ <... <x _N ), data points (x _i , y _i ) to be regressed by the first regression line (i = 1, ..., k-1; k is an integer greater than or equal to 3 and less than or equal to N-1), and data points (x _i , y _i ) (i = k,..., N) to be regressed by the second regression line Of the residuals of all of the first and second regression lines for the integer k separating This may be done by finding the value of k (eg in round-robin fashion) that minimizes the multiply-sum.

The probe saturation magnetization characteristic detection unit 219 acquires the intensity Hi of the AC magnetic field H_AC at the transition point T_PNT detected by the SBI change transition point detection unit 218 and the intensity (SBI _2nd ) of the secondary sideband, Thus, the saturation magnetization of the soft magnetic probe PRB and the intensity Hi of the AC magnetic field H_AC when the magnetization of the soft magnetic probe PRB is saturated are detected. Specifically, the transition point T_PNT corresponds to the alternating magnetic field strength Hi when the magnetization of the soft magnetic probe PRB is saturated. Since the gradient ∂H _z0 ^ac / ∂z of the AC magnetic field at the transition point T_PNT can be known from the AC magnetic field strength Hi at the transition point T_PNT, based on the intensity SBI _2nd of the secondary sideband at the transition point T_PNT. The magnitude of the saturation magnetization q _s of the soft magnetic probe PRB can be evaluated from the equations (6) and (19).

Although the above description of the present invention exemplifies the evaluation device 21 having the SBI extraction unit 216 for extracting the primary and secondary sideband intensities SBI _1st and SBI _2nd , the present invention is not limited to this embodiment. For example, it is also possible to use an evaluation apparatus in a form in which the SBI extraction unit extracts only the intensity SBI _2nd of the secondary sideband. The SBI extraction unit may extract higher-order sideband intensities together with the second-order sideband intensities SBI _2nd or the first- and second-order sideband intensities SBI _1st and SBI _2nd .

<1.5 Evaluation method of probe for magnetic force microscope (2)>
FIG. 16 is a flowchart showing an evaluation procedure when evaluating the soft magnetic probe PRB using the evaluation device 21 of FIG.
The evaluation method shown in FIG. 16 includes a probe attachment step S200, a probe demagnetization step S201, a probe excitation step S202, an AC magnetic field generation step S203, an AC magnetic field control step S204, a probe vibration detection step S205, and a spectrum measurement step S206. , SBI extraction step S207, SBI change measurement step S208, SBI change transition point detection step S209, and probe magnetization saturation characteristic detection step S210.

Probe Mounting Step S200: The soft magnetic probe PRB is mounted on a probe holder not shown in FIG.
Probe Demagnetization Step S201: The probe magnetization is AC demagnetized (for example, it is slowly reduced from 5 kOe to 0 kOe at AC 100 Hz). This step is carried out to put the probe in a demagnetized state without having a DC magnetic pole when applying an AC magnetic field to the probe.

  The processes of probe excitation step S202, AC magnetic field generation step S203, AC magnetic field control step S204, probe vibration detection step S205, spectrum measurement step S206, SBI extraction step S207, and SBI change measurement step S208 are shown in FIG. Step) of probe excitation step S102, AC magnetic field generation step S103, AC magnetic field control step S104, probe vibration detection step S105, spectrum measurement step S106, SBI extraction step S107, and SBI change measurement step It is the same as the process of S108.

  In the alternating current magnetic field control step S204, when changing the intensity of the alternating current magnetic field H_AC discontinuously (stepwise), from one measurement point (AC magnetic field strength) to the next measurement point (AC magnetic field strength) It is preferable to ac demagnetize the probe magnetization once before moving.

In SBI change transition point detection step S209, the change of the secondary sideband strength SBI _2nd measured in SBI change measurement step S208 with respect to the alternating current magnetic field strength Hi changes the alternating current magnetic field strength at which transition from quadratic function change to linear function change is It detects as a transition point T_PNT.

In the probe saturation magnetization characteristic detection step S210, the transition point T_PNT detected in the SBI change transition point detection step S209 and the intensity SBI _2nd of the secondary side band at the transition point T_PNT are acquired, and based on these, The saturation magnetization of the magnetic probe PRB and the intensity Hi of the AC magnetic field H_AC when the magnetization of the soft magnetic probe PRB is saturated are detected.

FIG. 17 plots the characteristics of the intensity of the spectrum of the probe vibration with respect to the intensity Hi of the alternating magnetic field H_AC when using a probe tip having an Fe—Co—B magnetic film as the probe tip of the soft magnetic probe. Is a graph.
In FIG. 17, it can be seen that the slope of the characteristic curve changes significantly after passing the transition point T_PNT (inflection point). By detecting the transition point T_PNT, the value of the magnetic field at which the magnetization of the probe reaches saturation can be determined.
In FIG. 17, with respect to two soft magnetic probes (L1 and L2) having probe tips having a magnetic film made of Fe--Co--B on the surface, a first order with a frequency equal to the frequency of the applied alternating magnetic field. a sideband graph showing the alternating field amplitude dependence of the spectral intensity SBI _1st, and the spectral intensity SBI _2nd second order sidebands having a frequency twice the frequency of the applied AC magnetic field (log-log plot).
In the graph of FIG. 17, the gradient SBI _2nd of the secondary sideband changes before and after the transition point T_PNT in both L1 and L2. Before passing the transition point T_PNT, the change in the intensity SBI _2nd of the second sideband is quadratically (proportional to the square of the alternating magnetic field amplitude Hi) with respect to the alternating magnetic field amplitude Hi, but the transition point T_PNT If it passes, the change of the intensity SBI _2nd of the secondary sideband transitions to a linear functional change (proportional to the first power of the alternating magnetic field amplitude Hi) with respect to the alternating magnetic field amplitude Hi.
The intensity SBI _1st of the primary sideband is smaller than the intensity SBI _2nd of the secondary sideband in both L1 and L2. This fact indicates that the probe has soft magnetism. The intensity SBI _1st of these first-order sidebands increases until before the transition point T_PNT with the increase of the alternating magnetic field amplitude Hi, but decreases after the transition point T_PNT. This means that since the magnetization curve of the probe is a minor loop up to the transition point T_PNT, residual magnetization may remain at the end of the previous measurement when making measurements while increasing the AC magnetic field amplitude, but the transition point After passing T_PNT, it is assumed that the magnetization curve of the probe becomes a major loop that saturates, and the residual magnetization approaches zero at the end of the previous measurement.

FIG. 18A shows the secondary sideband strength SBI _{2nd for} various soft magnetic probes (probe tips made of Ni-Fe, Co-Zr-Nb, Fe-Co-B, and Fe-Co). Shows the AC magnetic field amplitude dependency of The magnetic Fe-Co-B probe that saturates in the area indicated by the white arrow in the figure can obtain high magnetization (secondary sideband strength) in a low AC magnetic field H_AC, so it can be used as a soft magnetic probe. It turns out that it is excellent.
FIG. 18B shows, from the results of FIG. 18A, for each soft magnetic probe, the AC magnetic field amplitude at which the magnetization of the probe reaches saturation and the intensity of the secondary sideband at that time. It is summarized in the table and the correlation diagram. The Fe-Co-B soft magnetic probe has a good performance of a soft magnetic probe because the AC magnetic field at which the magnetization of the probe reaches saturation is low and the intensity of the secondary sideband is large. I understand that.

As described above, the case where the probe is a hard magnetic probe has been described in the first embodiment, but the apparatus and method of the first embodiment can be applied to a paramagnetic probe, a superparamagnetic probe and a diamagnetic probe.
In the second embodiment, although the case where the probe is a soft magnetic probe has been described, the apparatus and method of the first embodiment can be applied to a paramagnetic probe, a superparamagnetic probe and a diamagnetic probe.

In the above description of the present invention, the evaluation method of the form of extracting the intensities SBI _1st and SBI _2nd of the primary and secondary sidebands in the SBI extraction step S207 is exemplified, but the present invention is not limited to this form. For example, it is also possible to set it as an evaluation device of a form which extracts only intensity SBI _2nd of a secondary side band in an SBI extraction step. In the SBI step, higher-order sideband intensities may be extracted together with the second-order sideband intensities SBI _2nd or the first- and second-order sideband intensities SBI _1st and SBI _2nd .

<1.6 Evaluation Device for Magnetic Force Microscope Probe (3)>
FIG. 19 is an explanatory view showing a third embodiment of the evaluation device for a probe for a magnetic force microscope of the present invention.
In FIG. 19, a paramagnetic probe PRB is used as a probe.
In FIG. 19, the evaluation device 31 includes a probe excitation unit 311, an AC magnetic field generation unit 312, an AC magnetic field control unit 313, a probe vibration detection unit 314, a spectrum measurement unit (spectrum analyzer) 315, an SBI extraction unit 316, and SBI change. A measurement unit 317 and an evaluation result output unit 319 are provided.

  The paramagnetic probe PRB is a cantilever made of silicon, and in FIG. 19, a probe tip TIP whose surface is formed of a paramagnetic thin film is formed on the lower surface of the tip of the paramagnetic probe PRB.

The configurations of the probe excitation unit 311, AC magnetic field generation unit 312, AC magnetic field control unit 313, probe vibration detection unit 314, spectrum measurement unit (spectrum analyzer) 315, and SBI change measurement unit 317 are shown in FIG. Configuration of probe excitation unit 111, AC magnetic field generation unit 112, AC magnetic field control unit 113, probe vibration detection unit 114, spectrum measurement unit (spectrum analyzer) 115, and SBI change measurement unit 117 in the evaluation device 11 of the embodiment Is the same as
Further, the configuration of the SBI extraction unit 316 is the same as the configuration of the SBI extraction unit 116 in the evaluation device 11 of FIG. 9 (the first embodiment) except that only the secondary sideband intensity SBI _2nd is extracted. .

The evaluation result output unit 319 evaluates the characteristics of the paramagnetic probe PRB based on the change in the intensity (SBI _2nd ) of the _second side band with respect to the intensity Hi of the alternating magnetic field H_AC measured by the SBI change measurement unit 317. Output the result ES.
The evaluation result output unit 319 outputs a higher evaluation result ES as the strength SBI _2nd of the second side band SB_2nd increases when the AC magnetic field control unit 313 increases the strength of the AC magnetic field H_AC.
The method of determining the evaluation result ES based on the change of the intensity (SBI _2nd ) of the _second side band with respect to the intensity Hi of the alternating magnetic field H_AC is not particularly limited, but the evaluation result output unit 319 is not limited thereto. It can be performed by the function G (SBI _2nd ) which monotonously increases with the increase of the sideband strength SBI _2nd of. As the value of the secondary sideband intensity (SBI _2nd ) used by the evaluation result output unit 319 to determine the evaluation result ES, for example, the intensity Hi of the alternating magnetic field H_AC can be generated from the alternating magnetic field generation unit 312 The value of the secondary sideband strength (SBI _2nd ) at the maximum strength can be preferably employed.

In the above description of the present invention, the evaluation device 31 including the SBI extraction unit 316 that extracts the secondary sideband strength SBI _2nd has been illustrated, but the present invention is not limited to this form. For example, the SBI extraction unit may extract the intensity SBI _1st of the primary sideband or the intensity of the higher-order sideband in addition to the intensity SBI _2nd of the secondary sideband. For example, according to the form of extracting the intensity SBI _1st of the primary sideband in addition to the intensity SBI _2nd of the secondary sideband, when used for product inspection and production control of the magnetic probe, It becomes possible to detect a defect such as a mixture of ferromagnetic components in the thin film.

  In the above description, the evaluation device 31 in the form of evaluating the paramagnetic probe PRB is exemplified, but the probe that can be evaluated by the evaluation device 31 is not limited to the paramagnetic probe. In the evaluation apparatus 31 described above, not only the probe in which the probe tip has a paramagnetic substance, but the probe in which the probe tip has a diamagnetic substance, and the probe tip exhibits superparamagnetism It can also be used for the evaluation of probes comprising materials.

<1.7 Evaluation method of probe for magnetic force microscope (3)>
FIG. 20 is a flowchart showing an evaluation procedure when evaluating the paramagnetic probe PRB using the evaluation device 31 of FIG.
The evaluation method shown in FIG. 20 includes a probe mounting step S300, a probe demagnetization step S301, a probe excitation step S302, an AC magnetic field generation step S303, an AC magnetic field control step S304, a probe vibration detection step S305, and a spectrum measurement step S306. , SBI extraction step S307, SBI change measurement step S308, and evaluation result output step S310.

Processing of probe attachment step S300, probe demagnetization step S301, probe excitation step S302, AC magnetic field generation step S303, AC magnetic field control step S304, probe vibration detection step S305, spectrum measurement step S306, and SBI change measurement step S308 FIG. 10 shows the flow chart of FIG. 10 (first embodiment), probe mounting step S100, probe demagnetization step S101, probe excitation step S102, AC magnetic field generation step S103, AC magnetic field control step S104, probe vibration It is the same as the processing of detection step S105, spectrum measurement step S106, and SBI change measurement step S108.
Further, the processing of the SBI extraction step S307 is the same as the processing of the SBI extraction step S107 shown in the flowchart of FIG. 10 (the first embodiment) except that only the intensity SBI _2nd of the secondary sideband is extracted. is there.

  In the alternating current magnetic field control step S304, when changing the intensity of the alternating current magnetic field H_AC discontinuously (stepwise), from one measurement point (AC magnetic field strength) to the next measurement point (AC magnetic field strength) It is preferable to ac demagnetize the probe magnetization once before moving.

Evaluation Result Output Step S310: The characteristics of the paramagnetic probe PRB are evaluated based on the change in the secondary sideband intensity (SBI _2nd ) with respect to the intensity Hi of the alternating magnetic field H_AC measured in the SBI change measurement step S308. . Here, when the intensity Hi of the alternating magnetic field H_AC is increased in the alternating magnetic field control step S304, the higher the intensity (SBI _2nd ) of the secondary side band SB_2nd is, the higher the evaluation result ES is output (step S310A).
The method of determining the evaluation result ES based on the change of the intensity (SBI _2nd ) of the _second side band with respect to the intensity Hi of the alternating magnetic field H_AC in the evaluation result output step S310 is not particularly limited. It can be performed by the function G (SBI _2nd ) which monotonically increases with the increase of the _second sideband intensity SBI _2nd . As a value of the intensity (SBI _2nd ) of the secondary side band used to determine the evaluation result ES in the evaluation result output step S310, for example, the intensity Hi of the alternating magnetic field H_AC can be generated in the alternating magnetic field generation step S303. The value of the secondary sideband strength (SBI _2nd ) at the maximum strength can be preferably employed.

In the above description of the present invention, the evaluation method of the form of extracting the intensity SBI _2nd of the secondary side band in the SBI extraction step S307 is exemplified, but the present invention is not limited to the form. For example, in the SBI extraction step, higher-order sideband intensities may be extracted together with the first-order and second-order sideband intensities SBI _1st and SBI _2nd . According to the embodiment in which the intensity SBI _1st of the primary sideband is further extracted in addition to the intensity SBI _2nd of the secondary sideband, when used for product inspection and production control of the magnetic probe, the magnetic properties of the paramagnetic probe It becomes possible to detect a defect such as a mixture of ferromagnetic components in the thin film.

  Although the above description exemplifies the evaluation method of the mode of evaluating the paramagnetic probe PRB using the evaluation device 31, the probe that can be evaluated by the evaluation method shown in FIG. 20 is not limited to the paramagnetic probe. According to the evaluation method shown in FIG. 20, not only the probe in which the probe tip has a paramagnetic material, but also the probe in which the probe tip has a diamagnetic material, and the probe tip It is also possible to evaluate a probe comprising a material exhibiting magnetism.

  The above description of the present invention exemplifies a method for evaluating a paramagnetic probe in which the probe demagnetization step S301 is performed after the probe mounting step S300 and before the probe excitation step S302. It is not limited to. For example, it is known in advance that a probe PRB intended for a paramagnetic probe (or a diamagnetic probe or a superparamagnetic probe) does not have spontaneous magnetization (that is, does not have the property of a ferromagnetic substance). In the case where it is present, the probe demagnetization step S301 can be omitted. Also, for example, in the case where it is known in advance that the probe PRB intended for the paramagnetic probe (or the diamagnetic probe or the superparamagnetic probe) does not have spontaneous magnetization, in the alternating magnetic field control step S304. Even when the AC magnetic field strength is changed discontinuously, the process of AC demagnetizing the probe magnetization is omitted before moving from one measurement point (AC magnetic field strength) to the next measurement point (AC magnetic field strength) It is also possible.

<2. Magnetic force microscope and magnetic field adjustment method for control of magnetic force microscope>
In order to measure a direct current magnetic field from a sample with high sensitivity by applying an alternating current magnetic field to a soft magnetic probe, it is sufficient to use a soft magnetic probe with a high magnetic susceptibility whose magnetic moment largely changes with a small magnetic field .
However, when such a soft magnetic probe is used, if the direct current magnetic field from the sample largely changes depending on the measurement location, as described in FIG. The problem of becoming more saturated occurs.
The inventors of the present invention can reduce the influence of the direct current magnetic field of the sample on the probe by the control direct current magnetic field having a small gradient in the Z direction (direction perpendicular to the sample surface) or no gradient in the Z direction. It was conceived that the use of a high soft magnetic probe could avoid the magnetization saturation of the soft magnetic probe.
The present invention is based on the finding that the value of the AC magnetic field when the magnetization of the soft magnetic probe is saturated when a certain DC magnetic field is applied can be detected by analyzing the vibration spectrum of the probe. It came to eggplant.

  In the magnetic force microscope of the present invention, it is possible to adjust the strength of the control DC magnetic field and / or adjust the strength of the AC magnetic field according to the determination result of the magnetic field strength suitability determination unit. In addition, the strength range of the control DC magnetic field and / or the strength of the AC magnetic field applicable to the probe based on the strength of the control DC magnetic field and the strength of the AC magnetic field when the transition measured by the SBI change measurement unit occurs. The range can be determined.

In the control magnetic field adjustment method of the magnetic force microscope of the present invention, it is possible to adjust the strength of the control DC magnetic field and / or adjust the strength of the AC magnetic field according to the determination result of the control magnetic field suitability determination step.
In addition, the strength range of the control DC magnetic field and / or the strength of the AC magnetic field that can be applied to the probe based on the strength of the control DC magnetic field and the strength of the AC magnetic field when the transition measured in the SBI change measurement step occurs. The range can be determined.

<2.1 principle>
The principle of a magnetic force microscope using a soft magnetic probe for measuring a direct current magnetic field gradient from an observation sample, which is an application target of the magnetic force microscope and the control magnetic field adjustment method of the magnetic force microscope of the present invention, will be described.
First small DC magnetic field H _z ^dc applied to the soft magnetic probe from the observation sample and the amplitude H _z0 ^ac of externally applied magnetic field source to the soft magnetic probe alternating magnetic field ^{_{H z ac = H z0 ac cos}} (ω m t) Consider the case where the magnetization of the probe is not saturated by application of a magnetic field. At this time, since the AC change of the probe magnetization changes substantially in proportion to the AC magnetic field, the AC change of the probe magnetic pole also changes in proportion to the AC magnetic field, and Δk is expressed by the following equation.

ここで、外部からソフト磁性探針に加える交流磁場が、空間的に一様である場合、

Here, when the AC magnetic field externally applied to the soft magnetic probe is spatially uniform:

となり、Δｋは、次式で表される。

And Δk is expressed by the following equation.

したがって、角速度ω_mで周期的に変化する項

Therefore, the term periodically changing at angular velocity ω _m

に起因する周波数変調信号を、周波数復調することで、試料からの直流磁場勾配∂Ｈ_z ^dc／∂ｚの計測が可能になる。ここでｑ_ωm ^acはＨ_z0 ^acにほぼ比例して変化する（ｑ_ωm ^ac＝αＨ_z0 ^ac）ので、Δｋ（ω_mｔ）はＨ_z0 ^acの１乗に比例して変化することになる。

The frequency demodulation of the frequency modulation signal resulting from D.c. allows measurement of the direct current magnetic field gradient ∂H _z ^dc / ∂z from the sample. Here, since q _ωm ^ac changes almost in proportion to H _z0 ^ac (q _ωm ^ac = _{αH z0} ^ac ), Δk (ω _m t) changes in proportion to the first power of H _z0 ^ac .

また、角速度２ω_mで周期的に変化する項

Moreover, terms that periodically changes at the angular velocity 2 [omega _m

に着目すると、同様にｑ_ωm ^acはＨ_z0 ^acにほぼ比例して変化する（ｑ_ωm ^ac＝αＨ_z0 ^ac）ので、Δｋ（２ω_mｔ）はＨ_z0 ^acの２乗に比例して変化することになる。

Similarly, since q _ωm ^ac changes almost in proportion to H _z0 ^ac (q _ωm ^ac = _{αH z0} ^ac ), Δk (2ω _m t) changes in proportion to the square of H _z0 ^ac It will be.

Next, although the probe magnetization is not saturated only by the direct current magnetic field H _z ^dc applied from the observation sample to the soft magnetic probe, the alternating magnetic field H _z ^ac = H _z0 ^ac cos (ω) applied from the external magnetic field source to the soft magnetic probe Consider the case where the intensity H _{z 0} ^ac of _m t) is large, the magnetization of the probe is saturated by the application of an alternating magnetic field, and as a result the magnetic pole of the tip of the probe is saturated. When the magnetization curve is a square, the probe magnetization is M _s when the magnetic field direction is positive, and the probe magnetization is −M _s when the magnetic field direction is negative. Here, assuming that the saturation value of the magnetic pole at the tip of the probe is q _s , when H _{z 0} ^ac is large, the magnetic pole at the tip of the probe changes with time in a rectangular shape, and is expressed as follows.

このとき、Δｋは、次式で表される。

At this time, Δk is expressed by the following equation.

したがって、角速度ω_mで周期的に変化する項

Therefore, the term periodically changing at angular velocity ω _m

に起因する周波数変調信号を周波数復調することで、試料からの直流磁場勾配∂Ｈ_z ^dc／∂ｚの計測が可能になる。このとき、Ｈ_z0 ^acが増加してもｑ_sは変化しないので、Δｋ（ω_mｔ）はＨ_z0 ^acに対して一定となる。したがって、探針磁化が飽和した後は、Ｈ_z0 ^acを増加させても、試料からの直流磁場勾配∂Ｈ_z ^dc／∂ｚの計測感度は変化しないので、Ｈ_z0 ^acの増加は無意味であり、ソフト磁性探針は飽和直前で使用するのがよいことがわかる。
一方、角速度２ω_mで周期的に変化する項

The frequency demodulation of the frequency modulation signal resulting from the measurement enables the measurement of the DC magnetic field gradient ∂H _z ^dc / ∂z from the sample. At this time, since q _s does not change even if H _{z 0} ^ac increases, Δk (ω _m t) becomes constant with respect to H _{z 0} ^ac . Thus, after the probe magnetization is saturated, increasing the H _z0 ^ac, since the measurement sensitivity of the DC magnetic field gradients .differential.H _z ^dc / ∂z from the sample does not change, the increase in H _z0 ^ac is meaningless The soft magnetic probe is found to be used just before saturation.
Meanwhile, terms which periodically changes at the angular velocity 2 [omega _m

に着目すると、Ｈ_z0 ^acに比例してΔｋ（２ω_mｔ）は増加する。

Focusing on, in proportion to ^{_{H z0 ac Δk (2ω m t}} ) is increased.

以上のことから、測定前にソフト磁性探針の感度を最大にできる交流磁場Ｈ_z ^ac＝Ｈ_z0 ^acｃｏｓ（ω_mｔ）の振幅Ｈ_z0 ^acを知ることは重要である。これには、Δｋ（２ω_mｔ）に起因する周波数変調強度のＨ_z0 ^ac依存性が利用できる。すなわち、観察試料なしでソフト磁性探針に交流磁場Ｈ_z ^ac＝Ｈ_z0 ^acｃｏｓ（ω_mｔ）を印加し、周波数変調信号の角速度２ω_mで周期的に変化する項のＨ_z0 ^acに対する依存性の次数が２次から１次に変化するＨ_z0 ^acの値を測定することで、ソフト磁性探針の磁化が飽和する交流磁場の振幅を知ることができる。

From the above, it is important to know the amplitude H _z0 ^ac of the alternating magnetic field H _z ^ac = H _z0 ^ac cos (ω _m t) which can maximize the sensitivity of the soft magnetic probe before measurement. For this, the H _z0 ^ac dependency of the frequency modulation strength due to Δk (2ω _m t) can be used. That is, the alternating magnetic field H _z ^ac = H _z0 ^ac cos (ω _m t) is applied to the soft magnetic probe without an observation sample, and the dependence of the periodically changing term on the angular velocity 2ω _m of the frequency modulation signal on H _z0 ^ac By measuring the value of H _{z 0} ^ac in which the order of the characteristics changes from second to first, it is possible to know the amplitude of the AC magnetic field at which the magnetization of the soft magnetic probe is saturated.

Further, it is assumed that an AC magnetic field is applied from the external magnetic field source to the soft magnetic probe in a state where the direct current magnetic field H _z ^dc applied from the observation sample to the soft magnetic probe is large and the probe magnetization is almost saturated. In this case, since the alternating current variation q _ωm ^ac of the probe magnetic pole is substantially zero, Δk is expressed by the following equation.

したがって、探針振動の周波数変調が発生しなくなり、試料からの直流磁場の勾配∂Ｈ_z ^dc／∂ｚの計測が困難になる。
ソフト磁性探針の測定感度を保ったままで、観察試料から発生する直流磁場の勾配∂Ｈ_z ^dc／∂ｚを計測するには、交流磁場Ｈ_z ^ac＝Ｈ_z0 ^acｃｏｓ（ω_mｔ）の印加でソフト磁性探針の磁化を飽和させないことに加えて、観察試料から発生する直流磁場Ｈ_z ^dcと逆方向の直流磁場（Ｈ_z ^dc）^exを外部から印加することによりソフト磁性探針の磁化の飽和を防止することが必要である。ここで、外部から印加する直流磁場（Ｈ_z ^dc）^exは、∂Ｈ_z ^dc／∂ｚの測定結果に影響を与えないように、空間的に一様：

Therefore, frequency modulation of the probe vibration does not occur, and measurement of the gradient ∂H _z ^dc / ∂z of the direct current magnetic field from the sample becomes difficult.
To measure the gradient ∂H _z ^dc / ∂z of the direct current magnetic field generated from the observation sample while maintaining the measurement sensitivity of the soft magnetic probe, the alternating magnetic field H _z ^ac = H _z0 ^ac cos (ω _m t) In addition to the saturation of the magnetization of the soft magnetic probe by the application, the soft magnetic probe of the soft magnetic probe is externally applied with a DC magnetic field (H _z ^dc ) ^ex reverse to the DC magnetic field H _z ^dc generated from the observation sample. It is necessary to prevent saturation of the magnetization. Here, the externally applied direct current magnetic field (H _z ^dc ) ^ex is spatially uniform so as not to affect the measurement result of ∂H _z ^dc / ∂z:

である必要がある。
（Ｈ_z ^dc）^exの大きさは、観察試料の磁気力顕微鏡による走査範囲の中での、観察試料から発生する直流磁場Ｈ_z ^dcの最大値以上である必要がある。

It needs to be.
The size of (H _z ^dc ) ^ex needs to be equal to or greater than the maximum value of the direct current magnetic field H _z ^dc generated from the observation sample within the scanning range of the observation sample by the magnetic force microscope.

The measurement procedure in the magnetic force microscope of the present invention and the measurement procedure using the control method for adjusting a magnetic field of the magnetic force microscope of the present invention include the following (1) to (4).
(1) Without an observation sample, an AC magnetic field is applied to the soft magnetic probe, and from the AC magnetic field amplitude dependency of the frequency modulation spectrum by Δk (2ω _m t), the AC magnetic field amplitude at which the soft magnetic probe is saturated (maximum Estimate the measurement sensitivity).
(2) An AC magnetic field is applied to the soft magnetic probe to detect the DC magnetic field gradient of the observation sample, and the observation sample position where the absolute value of the DC magnetic field gradient is maximum is found. The observation sample position where the absolute value of the direct current magnetic field gradient is maximum includes a place where the direct current magnetic field is upward with respect to the sample surface and a place where the direct current magnetic field is downward with respect to the sample surface.
(3) The probe is moved to two points which are observation sample positions where the absolute value of these DC magnetic field gradients becomes maximum, and a DC magnetic field is applied from the outside, and Δk (ω _m t) or Δk From the external DC magnetic field dependence of the frequency modulation spectrum caused by (2ω _m t), a DC magnetic field value at which saturation of the probe magnetization does not occur is determined in advance.
(4) In the observation sample, the external direct current magnetic field of the direct current magnetic field value determined in (3) is reverse to the direct current magnetic field from the observation sample for the place where the direct current magnetic field from the sample is upward and downward with respect to the sample surface. Apply in the direction to measure.
The external DC magnetic field values at which the probe is not saturated may be individually determined at all observation points of the observation image.

In the present invention, the spectrum of the frequency modulation of the soft magnetic probe vibration is observed in order to detect the change in the magnitude of the frequency modulation of the vibration of the soft magnetic probe (the change of the apparent spring constant of the probe). .
By applying an alternating magnetic field H _z ^ac = H _z0 ^ac cos (ω _m t) to the soft magnetic probe, the soft magnetic probe is examined for the dependence of the frequency modulation of the induced ω _m on the alternating magnetic field amplitude H _z0 ^ac . It can be known whether the magnetization of the probe has reached saturation.
Specifically, the intensity of the control DC magnetic field H_DC is initially set to zero, and in this state, the magnitude of the AC magnetic field H_AC is changed stepwise.
For the control DC magnetic field H_DC, when the soft magnetic probe is given a magnetic field gradient, the effective spring constant of the soft magnetic probe is changed. Therefore, the gradient in the Z direction of the control DC magnetic field H_DC needs to be zero or small (close to zero as much as possible).

<2.2 Magnetic force microscope>
FIG. 22 is an explanatory view showing an embodiment of a magnetic force microscope of the present invention.
In FIG. 22, the magnetic force microscope 4 includes a soft magnetic probe (probe in the present invention) 40, a probe excitation unit 41, a combined magnetic field generation unit 42, a magnetic field control unit 43, a probe vibration detection unit 44, and a scanning unit 45. And a DC magnetic field characteristic measurement unit 46, a spectrum measurement unit 47, and a magnetization saturation detection unit 48.

The soft magnetic probe 40 is a cantilever made of silicon. At the tip of the arm 401, a conical probe tip 402 having a soft magnetic thin film 403 formed on the surface is provided. As a soft magnetic material constituting the soft magnetic thin film 403, for example, permalloy (Ni-Fe), Co-Zr-Nb, Fe-Co-B, and Fe-Co are adopted.
The probe excitation unit 41 can excite the soft magnetic probe 40. The probe excitation unit 41 includes an AC power supply 411 and a piezoelectric element 412 that vibrates the soft magnetic probe 40.

The composite magnetic field generation unit 42 can generate a composite magnetic field H_AC / DC of the AC magnetic field H_AC and the control DC magnetic field H_DC.
In FIG. 22, the synthetic magnetic field generation unit 42 includes an AC coil 421 driven by an alternating current AC and a DC coil 422 with a core 4221 driven by a DC current DC.
The magnetic field control unit 43 performs control to change the intensity of the alternating magnetic field H_AC generated from the alternating current coil 421 by the current AC that drives the alternating current coil 421.
Further, the magnetic field control unit 43 performs control to change the intensity of the control DC magnetic field H_DC generated from the DC coil 422 by the current DC for driving the DC coil 422. The control of changing the strength of the control DC magnetic field by the magnetic field control unit 43 and the control of changing the strength of the alternating magnetic field can be performed independently. That is, the AC magnetic field H_AC can be changed discontinuously (stepwise) while fixing the control DC magnetic field H_DC to a certain value.

FIG. 23A shows the relationship between an alternating magnetic field H_AC, a control DC magnetic field H_DC, and a direct current magnetic field H_DC _SMPL generated by the sample SMPL set on the stage STG.
The z-direction component (direction perpendicular to the sample surface) of the alternating magnetic field H_AC is sufficiently spatially uniform to the z-direction component of the direct current magnetic field H_DC _SMPL generated by the sample SMPL. Specifically, the intensity H z ₀ ^ac of the z-direction component of the alternating magnetic field H_AC and the intensity H _z ^dc of the z-direction component of the direct current magnetic field H_DC _SMPL generated by the sample SMPL set to the stage STG are It is preferable to satisfy the relationship of 36).

また、制御用直流磁場Ｈ＿ＤＣのｚ方向成分も、ステージＳＴＧにセットされた試料ＳＭＰＬが発生する直流磁場Ｈ＿ＤＣ_SMPLのｚ方向成分に対して、十分に空間的に一様である。具体的には、制御用直流磁場Ｈ＿ＤＣのｚ方向成分（Ｈ_z ^dc）^exと、ステージＳＴＧにセットされた試料ＳＭＰＬが発生する直流磁場Ｈ＿ＤＣ_SMPLのｚ方向成分Ｈ_z ^dcとは、次の式（４３）の関係を満たすことが好ましい。

The z-direction component of the control DC magnetic field H_DC is also sufficiently spatially uniform to the z-direction component of the DC magnetic field H_DC _SMPL generated by the sample SMPL set on the stage STG. Specifically, z-direction components of the control DC field H_DC and (H _z ^{dc) ex,} the z-direction component H _z ^dc DC magnetic field H_DC _SMPL the sample SMPL, which is set on the stage STG occurs, the following formula It is preferable to satisfy the relationship of (43).

図２３（Ｂ）に示すように、合成磁場発生部４２は、交流電流ＡＣと直流電流ＤＣとの合成電流ＳＣにより駆動される一つのコイル４２０から構成することもできる。合成磁場発生部４２を一つのコイル４２０から構成した場合には、磁場制御部４３からは交流電流ＡＣと直流電流ＤＣとの合成電流ＳＣが出力される。

As shown in FIG. 23B, the combined magnetic field generation unit 42 can also be configured of one coil 420 driven by combined current SC of alternating current AC and direct current DC. When the combined magnetic field generation unit 42 is configured of one coil 420, the combined current SC of the alternating current AC and the direct current DC is output from the magnetic field control unit 43.

The probe vibration detection unit 44 detects the vibration of the soft magnetic probe 40 and generates a vibration detection signal VIB. The probe vibration detection unit 44 includes a laser (LSR) 441 and a photo detector (PD) 442. A reflection mirror is formed on the top end of the soft magnetic probe 40. The laser beam LB emitted from the LSR 441 is reflected by the top surface of the soft magnetic probe 40 and is incident on the PD 442.
The scanning unit 45 can space drive (XY drive) the soft magnetic probe 40 so that the soft magnetic probe 40 can scan the surface of the sample SMPL. FIG. 23 shows an example in which the surface of the sample SMPL is scanned by the soft magnetic probe 40 by moving the stage STG in which the sample SMPL is set. However, the soft magnetic probe 40 is moved. It is also possible to scan the top surface of the sample SMPL by the magnetic probe 40.

The DC magnetic field characteristic measurement unit 46 acquires the vibration detection signal VIB detected by the probe vibration detection unit 44, and analyzes the vibration modulation generated on the soft magnetic probe 40 to obtain the DC magnetic field characteristic of the surface of the sample SMPL. It can be measured.
The spectrum measurement unit 47 acquires the vibration detection signal VIB detected by the probe vibration detection unit 44, and measures the spectrum of the vibration detection signal VIB.
The spectrum measurement unit 47 fixes the control DC magnetic field H_DC to a certain value by the synthetic magnetic field generation unit 42 and changes the alternating current magnetic field H_AC discontinuously (stepwise) by the intensity H of the alternating current magnetic field H_AC. _Measure every _ACi .

The magnetization saturation detection unit 48 makes the alternating current magnetic field H_AC discontinuous (step) whether the magnetization of the soft magnetic material thin film 403 formed on the probe tip 402 is saturated or not when measuring the direct current magnetic field H_DC _SMPL of the sample SMPL. Can be detected (based on second-order sideband changes) based on the transition of the spectrum when changed.

Changes in the secondary sidebands can be detected visually based on the spectrum diagram.
Also, as shown in FIG. 24, the apparatus can be detected (instruments detecting) by configuring the magnetization saturation detection unit 48 from the SBI extraction unit 481, the SBI change measurement unit 482, and the magnetic field strength suitability determination unit 483.

In FIG. 24, the SBI extraction unit 481 extracts the intensity SBI_2nd of the secondary side band of the spectrum measured by the spectrum measurement unit 47.
The SBI change measurement unit 482 changes the strength H _ACi of the AC magnetic field H_AC from a certain value to a predetermined value under the control DC magnetic field H_DC whose strength is set to a certain value within a predetermined range including zero, and extracts the SBI. The presence or absence of a change in the dependence of the intensity (SBI 2 nd) of the secondary sideband extracted by the unit 481 on the alternating current magnetic field intensity H _ACi is detected. Then, when a change in dependence on the alternating magnetic field intensity H _ACi of the intensity of the second-order sideband occurs, change in dependence occurs against the alternating magnetic field intensity H _ACi of the intensity of the second-order sideband (SBI_2nd) Measure the intensity H _ACi of the alternating magnetic field H_AC at the time of

In FIG. 25 (A), when the strength of the control DC magnetic field is changed, the double-logarithmic plot of the strength characteristics of the secondary side band SBI_2nd with respect to the change in strength of the AC magnetic field H_AC created by the SBI extraction unit 481. Shows how the graph changes. FIG. 25B is a graph showing a change in AC magnetic field intensity (probe saturation magnetic field) at a change point (transition point) T_PNT of the slope of the strength characteristic with respect to a control DC magnetic field strength. At the transition point T_PNT, the order of the dependence of the intensity of the second sideband on the alternating current magnetic field changes from second to first. FIG. 25C is a graph in which the sum of the AC magnetic field strength at the transition point T_PNT and the control DC magnetic field strength is plotted against the control DC magnetic field strength. From FIGS. 25A and 25B, when the control DC magnetic field is applied from the outside with the AC magnetic field strength kept constant, the transition point at which the probe reaches saturation changes by the amount of application of the control DC magnetic field. I understand that. From FIG. 25 (C), it can be confirmed that the maximum value of the magnetic field applied to the probe is the sum of the amplitude value of the alternating magnetic field and the direct current magnetic field value from the outside.
In the magnetic force microscope 4 having the configuration shown in FIG. 2, FIGS. 25 (A) to 25 (C) show that (Fe ₇₀ Co ₃₀ ) ₈₅ B on the surface of the probe tip of Si probe as the soft magnetic probe PRB. ₁₅ based on the result of measurement without an observation sample using a probe having a magnetic thin film (film thickness 30 nm) formed and an electromagnet as a magnetic field source.

The magnetic field strength aptitude determining unit 483 is a measurement result by the SBI change measuring unit 482 (whether or not there is a change in the AC magnetic field intensity H _ACi dependency of the second _sideband intensity _{SBI_2nd} , and (the second sideband intensity AC magnetic field Based on the intensity H _ACi of the alternating magnetic field H_AC when there is a change in the alternating magnetic field intensity dependence of the intensity SBI_2nd of the second-order sideband) (when there is a change in the intensity dependence), The suitability of the strength and / or the strength of the alternating magnetic field H_AC can be determined.

For example, it is assumed that the intensity of the control DC magnetic field H_DC is fixed to a certain value, the intensity of the AC magnetic field H_AC is changed, and the spectrum is measured by the spectrum measuring unit 47.
When the magnetic field strength suitability determination unit 483 detects the change point T_PNT of the slope of the strength characteristic, the strength of the AC magnetic field H_AC at that time is from the strength of the AC magnetic field applied to the measurement of the DC magnetic field characteristic of the surface of the sample SMPL. If too large, it is possible to judge that both the intensity of the control DC magnetic field H_DC and the intensity of the alternating magnetic field H_AC are appropriate.

On the other hand, when the magnetic field strength suitability determination unit 483 detects the change point T_PNT of the slope of the strength characteristic, the strength of the alternating magnetic field H_AC at that time is the magnitude of the alternating magnetic field applied to the measurement of the DC magnetic field characteristic of the surface of the sample SMPL. If it is less than the intensity, it can be determined that the intensity of the control DC magnetic field H_DC or the intensity of the alternating magnetic field H_AC is inappropriate.
In this case, it is necessary to reduce the strength of the control DC magnetic field H_DC or to reduce the strength of the AC magnetic field H_AC. Therefore, the strength of the control DC magnetic field H_DC or the strength of the AC magnetic field H_AC is changed again. , Measure the spectrum again to determine the suitability of the magnetic field strength.

As described above, in the magnetic force microscope 4 of FIG. 22, the AC magnetic field H_AC and the DC magnetic field for control H_DC are applied to the soft magnetic probe 40 being excited, and the soft magnetic probe 40 causes the DC magnetic field H_DC _SMPL to be applied. Scan the surface of the sample SMPL.
In this scanning, by detecting the vibration of the soft magnetic probe 40, the DC magnetic field characteristic (DC magnetic field H_DC _SMPL ) of the surface of the sample SMPL can be measured.

<2.3 Magnetic Field Adjustment Method for Control of Magnetic Force Microscope>
FIG. 26 is a flow chart showing processing in the case of carrying out the control magnetic field adjustment method of the present invention using the evaluation apparatus shown in FIG.
Sample setting step S400: The sample SMPL to be measured is set on the sample table.
Demagnetization Step S410: The magnetization of the soft magnetic probe 40 is AC demagnetized. For example, an alternating current magnetic field with a frequency of 100 Hz is applied to the probe tip 402 so that the intensity decreases gradually from 5 kOe to 0 kOe.

Probe Excitation Step S420: The soft magnetic probe 40 is excited at a predetermined angular frequency ω ₀ .
Magnetic field generation step S430: A combined magnetic field H_AC / DC of the alternating current magnetic field H_AC and the control DC magnetic field H_DC is generated, and the combined magnetic field H_AC / DC is applied to the probe 410. As described above, it is preferable that the AC magnetic field H_AC, the control DC magnetic field H_DC, and the DC magnetic field H_DC _SMPL generated by the sample SMPL set on the stage STG satisfy the relationships of equations (42) and (43) .
At this time, the intensity of the control DC magnetic field H_DC is set to the initial value H _DCi (r ₁ ) (S4301). Here, H _DCi (r ₁ ) = 0.
Further, the intensity of the alternating magnetic field H_AC is set to the initial value H _ACi (s ₁ ) (S4302).

The magnetic field control step S440 includes a DC magnetic field control step S4401 and an AC magnetic field control step S4402.
DC magnetic field control step S4401: In the zeroth loop (m = 1), the intensity of the control DC magnetic field H_DC is set to H _DCi (r ₁ ), and in the (j−1) th loop (m = j), The intensity of the control DC magnetic field H_DC is set to H _DCi (r _j ). Here, H _DCi (r ₁ ) <H _DCi (r ₂ ) <... <H _DCi (r _M ).
AC magnetic field control step S4402: In the zeroth loop (n = 1), the strength of the AC magnetic field H_AC is set to H _ACi (s ₁ ).
In the k-th loop (n = k + 1), the intensity of the alternating magnetic field H_AC is set to H _ACi (s _m ). Here, H _ACi (s ₁ ) <H _ACi (s ₂ ) <... <H _ACi (s _N ).
Probe vibration detection step S450: The vibration of the soft magnetic probe 10 is detected to generate a vibration detection signal VIB.

Spectrum measurement step S460: The vibration detection signal VIB detected in the probe vibration detection step S450 is acquired, and the spectrum of the vibration detection signal VIB corresponding to the intensity H _ACi (s _n ) of the AC magnetic field H_AC is measured.
The processing of the magnetic field control step S440, the probe vibration detection step S450, and the spectrum measurement step S460 is repeated until n = N by sequentially increasing n.
Magnetization saturation detection step S470: When the magnetization of the magnetic thin film formed at the tip of the soft magnetic probe 40 is saturated at the time of measurement of the direct current magnetic field H_DC _SMPL of the sample SMPL (the intensity SBI _2nd of the second side band SB_2nd is The intensity H _ACi (s _n ) of the alternating magnetic field H_AC when the dependence on the alternating magnetic field intensity H _ACi is detected is detected based on changes over a plurality of spectra (n = 1, 2,... N).
Then, it is detected whether the intensity H _ACi (s _n ) of the AC magnetic field H_AC when the magnetization of the soft magnetic material thin film formed on the probe tip 402 is saturated is equal to or less than a predetermined value.
When the intensity H _DCi (r _m ) of the control DC magnetic field is inappropriate (when the intensity of the alternating magnetic field H_AC when the magnetization of the soft magnetic material thin film formed on the probe tip 402 is saturated exceeds a predetermined value) ) _Increases the strength H _DCi (r _m ) of the control DC magnetic field (increases the value of m by 1), and repeats steps S430 to S470.
When the intensity H _DCi (r _m ) of the control DC magnetic field is appropriate, the process is ended.

The magnetization saturation detection step S470 can include an SBI extraction step S4701, an SBI change measurement step S4702, and a control magnetic field suitability determination step S4703, as shown in FIG.
In SBI extraction step S4701, the intensity SBI _2nd of second-order sideband SB_2nd of the plurality of spectra measured in spectrum measurement step S460 is extracted.

In the SBI change measurement step S4702, the strength of the alternating magnetic field H_AC when the dependence of the secondary sideband strength SBI _2nd (r _m ) on the AC magnetic field strength H _ACi changes is measured.
That is, under the control DC magnetic field H_DC whose strength is H _DCi (r _m ), the strength H _ACi of the AC magnetic field H_AC is _changed from a certain value H _ACi (s ₁ ) to a predetermined value H _ACi (s _N ) SBI extraction step the intensity of the second-order sideband extracted in _{S4701 SBI 2nd (r m, s} n) of the alternating magnetic field intensity H _ACi of the alternating magnetic field H_AC when a change occurs in the dependent intensity H _ACi (s _n) Measure
In the control magnetic field suitability determination step S4703, the measurement result in the SBI change measurement step S4701 (the strength of the AC magnetic field H_AC when the AC magnetic field strength H _ACi dependent characteristic of the strength SBI _2nd of the _{second sideband SB_2nd} changes) Based on the above, the suitability of the control DC magnetic field strength H _DCi (r _m ) is determined.

In the control field adequacy evaluation step S4703, when the control DC magnetic field strength H _DCi (r _m) is improper is raised intensity H _DCi (r _m) a stage of control DC magnetic field (the value of m By one) and repeat steps S430 to S470. When the intensity H _DCi (r _m ) of the control DC magnetic field is appropriate, the process is ended.

11 evaluation apparatus 111 probe excitation unit 112 AC magnetic field generation unit 113 AC magnetic field control unit 114 probe vibration detection unit 115 spectrum measurement unit 116 SBI extraction unit 117 SBI change measurement unit 118 change transition point detection unit 119 evaluation result output unit 1111 AC Power supply 1112 Piezoelectric element 1141 Laser (LSR)
1142 Photo Detector (PD)
21 Evaluation apparatus 211 Probe excitation unit 212 AC magnetic field generation unit 213 AC magnetic field control unit 214 Probe vibration detection unit 215 Spectrum measurement unit 216 SBI extraction unit 217 SBI change measurement unit 218 Change transition point detection unit 219 Probe saturation magnetization characteristic detection Section 2111 AC power supply 2112 Piezoelectric element 2141 Laser (LSR)
2142 Photo Detector (PD)
31 Evaluation Device 311 Probe Excitation Unit 312 DC Magnetic Field / AC Magnetic Field Generation Unit 313 DC Magnetic Field / AC Magnetic Field Control Unit 314 Probe Vibration Detection Unit 315 Spectrum Measurement Unit 316 SBI Extraction Unit 317 SBI Change Measurement Unit 318 Probe Quality Detection Unit 3111 AC power supply 3112 Piezoelectric element 3141 laser (LSR)
3142 Photodetector (PD)
DESCRIPTION OF SYMBOLS 4 Magnetic force microscope 40 Soft magnetic probe 41 Probe excitation part 42 Synthetic magnetic field generation part 43 Magnetic field control part 44 Probe vibration detection part 45 Scanning part 46 DC magnetic field characteristic measurement part 47 Spectrum measurement part 48 Magnetization saturation detection part 401 Cantilever Arm 402 probe tip 403 soft magnetic material thin film 411 AC power supply 412 piezoelectric element 421 AC coil 422 DC coil 420 coil 441 laser (LSR)
442 Photodetector (PD)
481 SBI extraction unit 482 SBI change measurement unit 483 Magnetic field strength suitability determination unit

Claims (18)

An apparatus used for characterizing a probe for a magnetic force microscope for measuring a direct current magnetic field or an alternating current magnetic field generated from a sample, comprising:
A probe excitation unit for exciting the probe;
An alternating magnetic field generating unit that generates an alternating magnetic field and applies the alternating magnetic field to the probe;
An AC magnetic field control unit that controls the AC magnetic field generation unit so that the intensity of the AC magnetic field changes.
A probe vibration detection unit that detects a vibration of the probe and generates a vibration detection signal;
A spectrum measurement unit which acquires a vibration detection signal generated by the probe vibration detection unit and measures a spectrum of the vibration detection signal corresponding to the intensity of the alternating magnetic field;
Extracting the intensity of the second-order sideband appearing in the spectrum measured by the spectrum measurement unit, or extracting the intensity of the first-order and second-order sideband appearing in the spectrum measured by the spectrum measurement unit, SBI extractor,
An SBI change measurement unit that measures a change in the intensity of the side band extracted by the SBI extraction unit with respect to the intensity of the alternating magnetic field;
An evaluation device for a probe for a magnetic force microscope, comprising: an evaluation result output unit that evaluates the characteristic of the probe based on the change measured by the SBI change measurement unit. The evaluation apparatus according to claim 1, wherein
An evaluation device for a probe for a magnetic force microscope, wherein the probe tip of the probe comprises a ferromagnetic body, a paramagnetic body, a material exhibiting superparamagnetism, or a diamagnetic body. The evaluation device according to claim 1, wherein the probe tip of the probe comprises a hard magnetic material of a ferromagnetic material,
The SBI extraction unit extracts the intensity of the primary and secondary sidebands,
The evaluation result output unit
When the intensity of the alternating magnetic field is increased, the higher the intensity of the first-order sideband, the higher the evaluation result is output, and
The higher the intensity of the secondary sideband when the intensity of the alternating magnetic field is increased, the lower the evaluation result is output.
Evaluation device for probe for magnetic force microscope. The evaluation device according to claim 1, wherein the probe tip of the probe comprises a soft magnetic material of a ferromagnetic material,
The evaluation result output unit
An SBI change transition that detects, as a transition point, an alternating current magnetic field intensity at which a change of the intensity of the secondary sideband measured by the SBI change measurement unit with respect to the intensity of the alternating magnetic field changes from a quadratic function change to a linear function change. Point detection unit,
Probe saturation magnetization characteristic detection that acquires the intensity of the secondary sideband at the transition point, detects the saturation magnetization of the probe, and the intensity of the AC magnetic field when the magnetization of the probe is saturated And an evaluation unit for a probe for a magnetic force microscope. The evaluation device according to claim 1, wherein the probe tip of the probe comprises a paramagnetic or diamagnetic substance, or a material exhibiting superparamagnetic properties.
The evaluation result output unit outputs a higher evaluation result as the intensity of the second side band increases when the intensity of the AC magnetic field is increased.
Evaluation device for probe for magnetic force microscope. A method applied to the characterization of a magnetic force microscope probe for measuring a direct current magnetic field or an alternating current magnetic field generated from a sample,
A probe excitation step of exciting the probe;
An alternating magnetic field generating step of generating an alternating magnetic field and applying the alternating magnetic field to the probe;
An AC magnetic field control step of controlling the AC magnetic field such that the intensity of the AC magnetic field generated in the AC magnetic field generating step is changed;
A probe vibration detection step of detecting the vibration of the probe and generating a vibration detection signal;
A spectrum measurement step of acquiring a vibration detection signal generated in the probe vibration detection step and measuring a spectrum of the vibration detection signal corresponding to the intensity of the alternating magnetic field;
Extracting the intensity of the second-order sideband appearing in the spectrum measured in the spectrum measurement step, or extracting the intensity of the first-order and second-order sideband appearing in the spectrum measured in the spectrum measurement step, SBI extraction step,
An SBI change measurement step of measuring a change of the intensity of the sideband extracted in the SBI extraction step with respect to the intensity of the alternating magnetic field;
Evaluating the characteristics of the probe based on the change measured in the SBI change measurement step, an evaluation result output step. The evaluation method according to claim 6, wherein
A method for evaluating a probe for a magnetic force microscope, wherein the probe tip of the probe comprises a ferromagnetic material, a paramagnetic material, a material exhibiting superparamagnetism, or a diamagnetic material. The evaluation method according to claim 6, wherein the probe tip of the probe comprises a hard magnetic material of a ferromagnetic material,
Extracting the intensities of the first and second sidebands in the SBI extraction step;
In the evaluation result output step,
When the intensity of the alternating magnetic field is increased, the higher the intensity of the first-order sideband, the higher the evaluation result is output, and
The evaluation method for a probe for a magnetic force microscope, which outputs a lower evaluation result as the intensity of the secondary side band increases when the intensity of the alternating magnetic field is increased. The evaluation method according to claim 6, wherein the probe tip of the probe comprises a soft magnetic material of a ferromagnetic material,
The evaluation result output step is
An SBI change transition that detects, as a transition point, an alternating current magnetic field intensity at which a change of the intensity of the secondary sideband measured in the SBI change measurement step with respect to the intensity of the alternating magnetic field changes from a quadratic function change to a linear function change. Point detection step,
The transition point detected in the SBI change transition point detection step and the intensity of the secondary side band at the transition point are acquired, and the saturation magnetization of the probe and the magnetization of the probe are saturated. And a probe saturation magnetization characteristic detecting step of detecting the strength of the AC magnetic field. The evaluation method according to claim 6, wherein the probe tip of the probe comprises a paramagnetic or diamagnetic substance, or a material exhibiting superparamagnetism,
In the evaluation result output step, when the intensity of the AC magnetic field is increased, the higher the intensity of the second side band, the higher the evaluation result is output.
Evaluation method of probe for magnetic force microscope. An AC magnetic field and a control DC magnetic field are applied to the probe being excited, the surface of the sample is scanned by the probe, and the vibration of the probe is detected to measure the DC magnetic field of the surface of the sample Magnetic force microscope,
The probe having a probe tip having a magnetic thin film formed on the tip;
A probe excitation unit for exciting the probe;
A composite magnetic field generation unit that generates a composite magnetic field of the AC magnetic field and the control DC magnetic field;
A magnetic field control unit that performs control to change the strength of the control DC magnetic field, and performs control to fix the strength of the control DC magnetic field and to sequentially change the strength of the AC magnetic field;
A probe vibration detection unit that detects a vibration of the probe and generates a vibration detection signal;
A scanning unit that spatially drives the probe;
A direct current magnetic field characteristic measurement unit that measures a direct current magnetic field of the surface of the sample by acquiring a vibration detection signal detected by the probe vibration detection unit and analyzing modulation generated in the vibration of the probe;
A spectrum measurement unit which acquires a vibration detection signal detected by the probe vibration detection unit and measures a spectrum of the vibration detection signal corresponding to the intensity of the alternating magnetic field;
A magnetization saturation detection unit for detecting the intensity of the AC magnetic field when the magnetization of the magnetic thin film formed on the probe tip is saturated based on a change in sideband intensity of the spectrum measured by the spectrum measurement unit; ,
A magnetic force microscope characterized by comprising. The magnetic force microscope according to claim 11, wherein
The magnetization saturation detection unit
An SBI extraction unit for extracting the intensity of the secondary side band of the spectrum measured by the spectrum measurement unit;
Under the control DC magnetic field set to a certain value within a predetermined range including zero, the strength of the alternating current magnetic field is changed from a certain value to a predetermined value, and the second-order extracted by the SBI extraction unit Detecting the presence or absence of a transition from a quadratic function change to a linear function change of the change of the sideband intensity with respect to the intensity of the alternating current magnetic field and detecting the transition, the alternating current when the transition occurs An SBI change measurement unit that measures the strength of the magnetic field;
A magnetic field strength aptitude determining unit that determines the aptitude of the intensity of the control DC magnetic field and / or the aptitude of the ac magnetic field based on the measurement result by the SBI change measurement portion;
A magnetic force microscope characterized by comprising. The magnetic force microscope according to claim 11, wherein
The magnetic force microscope, wherein the magnetic thin film formed on the probe tip is made of a soft magnetic material. The magnetic force microscope according to claim 11, wherein
The magnetic force microscope, wherein the combined magnetic field generation unit includes a coil driven by combined current of alternating current and direct current. The magnetic force microscope according to claim 11, wherein
The magnetic force microscope, wherein the combined magnetic field generation unit comprises a first coil driven by an alternating current and a second coil driven by a direct current. An AC magnetic field and a control DC magnetic field are applied to the probe being excited, the surface of the sample is scanned by the probe, and the vibration of the probe is detected to measure the DC magnetic field of the surface of the sample Method of controlling a control magnetic field of a magnetic force microscope,
A probe excitation step of exciting the probe;
A control magnetic field generation step of generating a composite magnetic field of the AC magnetic field and the control DC magnetic field, and applying the composite magnetic field to the probe;
A magnetic field control step of performing control of changing the strength of the control DC magnetic field, and performing control of fixing the strength of the control DC magnetic field and changing the strength of the AC magnetic field;
A probe vibration detection step of detecting the vibration of the probe and generating a vibration detection signal;
A spectrum measurement step of acquiring a vibration detection signal detected in the probe vibration detection step and measuring a spectrum of the vibration detection signal corresponding to the intensity of the alternating magnetic field;
When measuring the direct current magnetic field of the sample, whether or not the magnetization of the magnetic thin film formed on the probe tip provided at the tip of the probe is saturated is a side band of the spectrum measured in the spectrum measurement step. A magnetization saturation detection step of detecting based on a change in intensity;
A method of adjusting a control magnetic field of a magnetic force microscope, comprising: The control magnetic field adjustment method according to claim 16.
The magnetization saturation detection step
An SBI extraction step of extracting the intensity of the second-order sideband of the spectrum measured in the spectrum measurement step;
The intensity of the control DC magnetic field is set to a value in a range including zero, the intensity of the AC magnetic field is changed from a value to a predetermined value, and the intensity of the secondary sideband extracted in the SBI extraction step Detecting the presence or absence of a transition from a quadratic function change to a linear function change of the change of the alternating magnetic field with the strength of the alternating magnetic field, and measuring the strength of the alternating magnetic field when the transition occurs when the transition is detected SBI change measurement step
A control magnetic field aptitude determination step of determining the aptitude of the control DC magnetic field strength and / or the ac magnetic field aptitude based on the measurement result in the SBI change measurement step;
A method of adjusting a magnetic field for control of a magnetic force microscope, comprising: 17. The magnetic force microscope according to claim 16, wherein
A method of adjusting a control magnetic field of a magnetic force microscope, wherein the magnetic thin film formed on the probe tip is made of a soft magnetic material.

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