CN103443632B - Magnetic force microscope and high spatial resolution magnetic field measuring method - Google Patents
Magnetic force microscope and high spatial resolution magnetic field measuring method Download PDFInfo
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- CN103443632B CN103443632B CN201280012040.7A CN201280012040A CN103443632B CN 103443632 B CN103443632 B CN 103443632B CN 201280012040 A CN201280012040 A CN 201280012040A CN 103443632 B CN103443632 B CN 103443632B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
- G01Q60/00—Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
- G01Q60/50—MFM [Magnetic Force Microscopy] or apparatus therefor, e.g. MFM probes
- G01Q60/52—Resonance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/038—Measuring direction or magnitude of magnetic fields or magnetic flux using permanent magnets, e.g. balances, torsion devices
- G01R33/0385—Measuring direction or magnitude of magnetic fields or magnetic flux using permanent magnets, e.g. balances, torsion devices in relation with magnetic force measurements
Abstract
In conventional magnetic force microscopes, it has been difficult to obtain a magnetic field distribution with phase information since the primary resonant frequency of a cantilever fluctuates during probe scanning and the phase of a modulation frequency signal fluctuates. The measurement time has been long since the excitation frequency is as low as approximately 100 Hz. Also it has been difficult to increase the S/N ratio in order to measure an indirect signal called an FM modulation signal. This magnetic force microscope is provided with a cantilever (2) with a probe (1) having a magnetic substance, a first oscillator (4) which is excited at a first resonant frequency, a displacement detection circuit (7), a fine adjustment element (16), a z-axis driving unit (12) which drives the fine adjustment element (16), a second oscillator (13) which is excited at a second resonant frequency, and a lock-in amplifier (21) which inputs a displacement signal and a reference signal. The z-axis driving unit (12) moves the probe (1) toward or away from a magnetic recording head (8) on the basis of the displacement signal and the first resonant frequency, and the lock-in amplifier (21) generates magnetic field data on the basis of the displacement signal and the reference signal.
Description
Technical field
The present invention relates to the Distribution of Magnetic Field on working sample surface and the magnetic force microscopy of concaveconvex shape and measure the high spatial resolution magnetic field measuring method of Distribution of Magnetic Field with high spatial resolution.
The application is by the Japanese patent application No. Patent 2011-049670 applied on March 7th, 2011 in Japan and based on the Japanese patent application No. 2011-270138 applied on Dec 9th, 2011, require right of priority in Japan, by referring to these applications, thus they are referred in the application.
Background technology
Towards the densification of magnetic recording system taking hard disk as representative, the magnetic characteristic of magnetic recording head and thin magnetic film is developed the method that Distribution of Magnetic Field carries out image conversion with high spatial resolution.In order to realize the method, propose some technology.
In non-patent literature 1 ~ 5, record the structure of the magnetic force microscopy employing frequency modulating technology in order to directly observe AC magnetic field and use this magnetic force microscopy to be determined at the result of the AC magnetic field picture produced from magnetic recording head when being applied with alternating current to the magnetic recording head of hard disk.
In addition, in patent documentation 1, record and the magnetic recording head as determined sample is applied and the technology of external magnetic field of resonance frequency different frequency of cantilever (cantilever) of magnetic force microscopy to shorten the minute that undertaken by magnetic force microscopy.
Prior art document
Patent documentation
Patent documentation 1: JP 2010-175534 publication.
Non-patent literature
Non-patent literature 1:H. Saito, H. Ikeya, G. Egawa, S. Ishio and S. Yoshimura, " Magnetic force microscopy of alternating magnetic field gradient by frequency modulation of tip oscillation ", JOURNAL OF APPLIED PHYSICS, 105,07D524 (2009);
Non-patent literature 2:W. Lu, Z. Li, K. Hatakeyama, G. Egawa, S. Yoshimura and H. Saito, " High resolution magnetic imaging of perpendicular magnetic recording head using frequency-modulated magnetic force microscopy with a hard magnetic tip ", APPLIED PHYSICS LETTERS 96,143104 (2010);
Non-patent literature 3: Tanaka, in willow, true island, the 71st applied physics association symposium, 17-P12-12,62 (2010);
Non-patent literature 4:H. Saito, W. Lu, K. Hatakeyama, G.. Egawa and S. Yoshimura " High frequency magnetic field imaging by frequency modulated magnetic force microscopy ", JOURNAL OF APPLIED PHYSICS 107,09D309 (2010);
Non-patent literature 5:W. Lu, K. Hatakeyama, G. Egawa, S. Yoshimura and H. Saito, " Characterization of Magnetic Field Distribution in a Trailing-Edge Shielded Head by Frequency-Modulated Magnetic Force Microscopy ", IEEE TRANSACTIONS ON MAGNETICS, VOL. 46, NO. 6, JUNE 2010.
Summary of the invention
The problem that invention will solve
In magnetic force microscopy disclosed in non-patent literature 1 ~ 5, first, the concaveconvex shape of determined sample surfaces is measured.In this existing magnetic force microscopy, in order to measure the concaveconvex shape of determined sample surfaces, and cantilever is vibrated with a resonance frequency, in the mode making the vibration amplitude of the front end of cantilever fixing, the surface of distance to determined sample controlling the probe and determined sample room being assemblied in cantilever front end is scanned.Then, be used in primary scanning the data of the concaveconvex shape of the determined sample surfaces stored, under the distance of probe and determined sample room is remained fixing state, measure the size in magnetic field and the state of phase place change along primary sweep trace.At this, because determined sample is excited with fixing excitation frequency, so detected signal becomes and this excitation frequency cantilever resonance frequency is carried out frequency modulation (PFM) (hereinafter also referred to as FM.) signal.FM demodulation is carried out to this signal, excitation frequency being input to lock-in amplifier (lock in amplifier) as with reference to frequency, by carrying out phase-locked detection, thus obtaining the data of the Distribution of Magnetic Field of determined sample surfaces.
But in above-mentioned existing magnetic force microscopy, result from resonance frequency change when probe scanning of cantilever, the also change of FM signal, consequently, as the phase place change of the FM signal of detection signal.Therefore, existing magnetic force microscopy has the shortcoming being difficult to the Rcos θ picture obtaining showing magnetic field size and phase place.In existing magnetic force microscopy, although by embedding phaselocked loop in Analytical system, thus can improve the variation of phase place, device becomes complicated and expensive.In addition, because be low to moderate about 100Hz ~ 1kHz to the excitation frequency of determined sample, so the throughput (throughput) that also there is the mensuration of time per unit is poor, the shortcoming that minute is elongated.In addition, although by only improving the excitation frequency to determined sample, thus there is the leeway be enhanced in this problem, in order to improve the excitation frequency to determined sample, a resonance frequency as modulating frequency just must be improved.Like this, just significantly must promoting the frequency response of the optical lever of the displacement detecting for carrying out cantilever, as also pointing out in non-patent literature 4, will the problem of Analytical system be produced.And then also there are the following problems, that is, in principle, by measure FM signal this indirectly signal makes S/N than uprising is very difficult.
In addition, in magnetic force microscopy disclosed in patent documentation 1, cantilever is vibrated with a resonance frequency, with different from the resonance frequency of cantilever and be that the frequency of integral multiple (or integral multiple/2) of resonance frequency of cantilever carries out excitation to determined sample.Thus, improve step response when locating mobile, shorten minute.But, in this existing magnetic force microscopy, because carry out excitation with the frequency of the resonance frequency not being cantilever to the excitation frequency of determined sample, therefore the Q of Analytical system is low, gain does not improve, and consequently, there is the shortcoming that can not improve the S/N ratio of detection signal.
So the object of the invention is to, providing a kind of does not need phaselocked loop while can obtain the magnetic force microscopy of the Distribution of Magnetic Field data of high S/N ratio with shorter minute.
For solving the scheme of problem
In order to solve above-mentioned problem, magnetic force microscopy of the present invention possesses: have the cantilever that the probe be made up of magnetic or the coating probe of magnetic or film form the probe of the body that is magnetic in front end; With the first oscillator of the first resonance frequency excitation cantilever arm of cantilever; Detect the displacement detector of the displacement of cantilever front end; Sample is fixed on upper surface, makes probe close relative to sample, separately or the fine motion element of the movement that makes to locate; Drive the drive division of fine motion element; With the second resonance frequency of above-mentioned cantilever, sample is carried out to the second oscillator of excitation; And the tiny signal amplifier inputted from the displacement signal of displacement detector output and the reference signal as the second resonance frequency.And drive division, based on the displacement of the cantilever front end detected by displacement detector and the first resonance frequency, makes probe close or separate relative to sample by driving fine motion element, thus the concaveconvex shape of working sample.Tiny signal amplifier, based on the concaveconvex shape of sample, displacement signal and above-mentioned reference signal, carries out work in the mode generating the output corresponding to the magnetic field of sample surfaces.
In addition, magnetic force microscopy of the present invention possesses: have the probe be made up of magnetic in front end or be coated with the cantilever that the probe of magnetic or film form the probe of the body that is magnetic; With the first oscillator of the first resonance frequency excitation cantilever arm of cantilever; Detect the displacement detector of the displacement of cantilever front end; Sample is fixed on upper surface, makes probe close relative to sample, separately or the fine motion element of the movement that makes to locate; Drive the drive division of fine motion element; Frequency with 1/2 of the second resonance frequency of above-mentioned cantilever carries out the second oscillator of excitation to sample; And the tiny signal amplifier inputted from the displacement signal of displacement detector output and the reference signal as the second resonance frequency.And drive division, based on the displacement of the cantilever front end detected by displacement detector and the first resonance frequency, makes probe close or separate relative to sample by driving fine motion element, thus the concaveconvex shape of working sample.Second a pair of oscillators sample carries out excitation, make it the external magnetic field of more than the coercive force of the magnetic producing probe, tiny signal amplifier, based on the concaveconvex shape of sample, displacement signal and reference signal, carries out work in the mode generating the output corresponding to the magnetic field of sample surfaces.
High spatial resolution magnetic field measuring method of the present invention has: have with the first resonance frequency excitation front end of cantilever the cantilever that the probe be made up of magnetic or the probe being coated with magnetic or film form the probe of the body that is magnetic by the first oscillator, based on displacement and first resonance frequency of cantilever front end, by making probe close or separate the step of concaveconvex shape of working sample relative to sample; And with the second resonance frequency of cantilever, excitation is carried out to sample by the second oscillator, based on displacement and second resonance frequency of the concaveconvex shape measured, cantilever front end, generate the step of the output corresponding to the magnetic field of sample surfaces.
In addition, high spatial resolution magnetic field measuring method of the present invention has: have with the first resonance frequency excitation front end of cantilever the cantilever that the probe be made up of magnetic or the probe being coated with magnetic or film form the probe of the body that is magnetic by the first oscillator, based on displacement and first resonance frequency of cantilever front end, by making probe close or separate the step of concaveconvex shape of working sample relative to sample; And by the second oscillator with 1/2 of the second resonance frequency of cantilever frequency excitation is carried out to sample, based on the concaveconvex shape measured, the displacement of cantilever front end and the second resonance frequency, generate the step of the output corresponding to the magnetic field of sample surfaces.Second a pair of oscillators sample carries out excitation, makes it the external magnetic field of more than the coercive force of the magnetic producing probe.
Invention effect
Because obtain Distribution of Magnetic Field data based on the second resonance frequency of cantilever, so not by the impact of the phase of the first resonance frequency, even if do not embed phaselocked loop, the Distribution of Magnetic Field data that resolution is high also can be obtained.Because the second resonance frequency for the cantilever determined sample being carried out to excitation can be set as the frequency higher than the first resonance frequency, the throughput of mensuration can be improved, and shorten minute.The signal showing detected Distribution of Magnetic Field is not FM signal, but based on the first resonance frequency independently frequency, i.e. the second resonance frequency, therefore, it is possible to obtain signal with high S/N ratio.
Being made it the external communication magnetic field of more than the coercive force of the magnetic producing probe by the second oscillator, when making the frequency of the twice of AC magnetic field equal with the secondary resonance frequency of cantilever, the spatial resolution of measurable Distribution of Magnetic Field can be improved.
Accompanying drawing explanation
Fig. 1 is the block diagram of the structure example that magnetic force microscopy of the present invention is shown.
Fig. 2 is the figure of the relation illustrated between the electric current of the field coil flowing through magnetic force microscopy of the present invention and the output voltage of displacement detecting circuit.
Fig. 3 is the figure (configuration picture (topography picture)) of the concaveconvex shape that the magnetic recording head measured by magnetic force microscopy of the present invention is shown.
Fig. 4 is the figure of the magnetic field size on the magnetic recording head surface measuring Fig. 3.
Fig. 5 be band phase information (magnetic field towards) measure Fig. 3,4 the figure in magnetic field on magnetic recording head surface.
Fig. 6 is the figure carrying out three-dimensional data process to the data in the magnetic field of Fig. 5 and obtain.
Fig. 7 is the figure of the determination data of the magnetic field size that the magnetic recording head surface measured by magnetic force microscopy of the present invention to compare with prior art is shown.
Fig. 8 is the figure of the determination data of the magnetic field size illustrated when carrying out excitation with the just in time frequency pair magnetic recording head identical with the magnetic recording head measured in the figure 7 of 6 times of cantilever resonance frequency.
Fig. 9 illustrates, in magnetic force microscopy of the present invention, exciting current is set to 1mA
rmscarry out the figure of the magnetic field measuring result of the magnetic recording head measured, Fig. 9 A illustrates the measurement result of Rcos θ component, and Fig. 9 B illustrates the measurement result of Rsin θ component.
Figure 10 illustrates in the magnetic force microscopy as variation of the present invention, and the exciting current determined sample being carried out to excitation is set to 5mA
rmsand the figure of measurement result when being applied above the coercitive external magnetic field of kicker magnet probe.Figure 10 A illustrates the measurement result of Rcos θ component, and Figure 10 B illustrates the measurement result of Rsin θ component.
Figure 11 illustrates in the magnetic force microscopy as variation of the present invention, and the exciting current determined sample being carried out to excitation is set to 10mA
rmsand the figure of measurement result when being applied above the coercitive external magnetic field of kicker magnet probe.Figure 11 A illustrates the measurement result of Rcos θ component, and Figure 11 B illustrates the measurement result of Rsin θ component.
Figure 12 illustrates in the magnetic force microscopy as variation of the present invention, and the exciting current determined sample being carried out to excitation is set to 20mA
rmsand the figure of measurement result when being applied above the coercitive external magnetic field of kicker magnet probe.Figure 12 A illustrates the measurement result of Rcos θ component, and Figure 12 B illustrates the measurement result of Rsin θ component.
Figure 13 is the block diagram of the structure of other variation that magnetic force microscopy of the present invention is shown.
Figure 14 is the configuration picture and Distribution of Magnetic Field picture that are measured by the magnetic force microscopy of the structure of Figure 13.Figure 14 A is magnetic field in order to generate below coercive force and exciting current is set to 1mA
rmstime configuration picture.Figure 14 B is the Distribution of Magnetic Field picture under the condition of Figure 14 A.Figure 14 C exceedes coercitive magnetic field to generate and exciting current is set to 20mA
rmstime configuration picture.Figure 14 D is the Distribution of Magnetic Field picture under the condition of Figure 14 C.
The measurement result of magnetic force microscopy when Figure 15 is to compare resolution and carrying out excitation to determined sample with exceeding coercive force with the AC magnetic field that frequency is equal with the secondary resonance frequency of cantilever.Figure 15 A illustrates Distribution of Magnetic Field.Figure 15 B illustrates Rcos θ picture.Figure 15 C illustrates Rsin θ picture.
Figure 16 A is the figure intensity distributions in the magnetic field in the cross section of the dotted line of Figure 13 D illustrated as voltage scaled value (cross section profile).Figure 16 B is to be illustrated and the figure carrying out Fourier transform to the data of the cross section profile of Figure 16 A and obtain by the function of Distribution of Magnetic Field as spatial frequency.
Figure 17 has been shown as to compare with variation and other variation and the figure of data that carries out Fourier transform to the cross section profile data of the dotted line of Figure 15 A ~ C and obtain.
Embodiment
[structure of magnetic force microscopy]
Fig. 1 is the block diagram of the structure example that magnetic force microscopy of the present invention is shown.
The leaf spring of the probe 1 with ferromagnetic is connected with (hereinafter also referred to as cantilever in front end.) 2 be fixed on piezoelectric element 3 in single armed beam-like.Probe 1 is the probe being formed with CoCrPt alloy firm on silicon materials surface.But magnetic is not limited to CoCrPt, can be other Co class alloy such as CoCr alloy, CoPt alloy, also can be other magnetic, such as ferrite (ferrite), Fe, Ni, FePt, their alloy or permalloy (permalloy) etc.The shape of probe 1 is circular cone or pyramid-shaped.Cantilever 2 is silicon systems.But being not limited to silicon system, also can be other materials such as silicon nitride (silicon nitride).In addition, in general, probe 1 and cantilever 2 are formed by one-body molded.But, in order to improve the resolution of mensuration, can be add at silicon cantilever the probe 1 be made up of carbon nano-tube, in addition, also needle-like magnetic can be made to carry out crystal growth in the front end of integrated probe 1.
First oscillator 4 is connected with piezoelectric element 3 in the fixing side of cantilever 2.First oscillator 4 makes it vibrate with the frequency drives piezoelectric element 3 of regulation, with a resonance frequency, cantilever 2 is vibrated.Although the first oscillator 4 is made up of the function generator of more vairable and produces sine wave, also can be made up of other sine wave generation circuit.
By semiconductor laser 5, by the photodetectors 6 of four segmentations and the optical lever that forms of displacement detecting circuit 7, in order to detect the vibrational state of cantilever 2, detecting with photodetector 6 laser that reflects at cantilever 2 and carrying out light-to-current inversion.Then, the amplitude of laser detected with displacement detecting circuit 7 and the change of phase place.In addition, carry out the displacement detecting of cantilever 2, be not limited to optical lever, the mode utilizing other interference light can be used, such as, the mode etc. of being undertaken by the focus error detection employing Optical fibre interferometric or prism, and then, the mode beyond interference light can also be used, such as, use the mode of magnetoresistive element or use the mode etc. of piezoelectric element.
The output of displacement detecting circuit 7 is connected with the bandpass filter 9 be connected in series, RMS-DC transducer 10, and the reversion input via error amplifier 11 is connected with z-axis drive division 12.Reference voltage 11a is connected with in the non-inverting input of error amplifier 11.And the output of error amplifier 11 is connected with z-axis drive division 12, the output of z-axis drive division 12 is connected with fine motion element 16 and drives the z scanner portion of fine motion element 16.Z scanner portion is driven in the vertical direction by the mensuration face of z-axis drive division 12 relative to the magnetic recording head 8 as determined sample.
Signal transacting control part 17 is connected with the xy scanner portion of fine motion element 16 and coarse motion mechanism 20 respectively via xy scanning driving part 18 and coarse motion mechanism drive part 19.The output of z-axis drive division 12 and xy scanning driving part 18 is also connected with signal transacting control part 17, and the concaveconvex shape data of signal transacting control part 17 to determined sample carry out signal transacting, output to monitor 22 as view data.
Magnetic recording head 8 as determined sample is fixed on the upper surface of the fine motion element 16 carrying out the location of determined sample in all directions of xyz axle with nm magnitude.Fine motion element 16 is fixed on the upper surface carrying out the location of determined sample and the coarse motion mechanism 20 of scanning in a wide range in all directions of xyz axle.Fine motion element 16 and coarse motion mechanism 20 control distance and the position on the front end of probe 1 and the surface of determined sample via z-axis drive division 12, xy scanning driving part 18, coarse motion mechanism drive part 19.In addition, fine motion element 16 is such as formed by piezoelectric element, according to the voltage applied by z-axis drive division 12 grade, controls the direction and the displacement that carry out displacement.On the other hand, coarse motion mechanism is by the driving means of machinery, and such as Motor Control carries out the position control to measuring platform.
The output of the second oscillator 13 is connected with the field coil 14 of the magnetic core of the magnetic recording head 8 be wound on as determined sample.Another terminal of field coil 14 is grounded via current-limiting resistance 15.In addition, the output of the second oscillator 13 is connected with the reference input of lock-in amplifier 21.The output of the displacement detecting circuit 7 of optical lever is connected with lock-in amplifier 21.Lock-in amplifier 21, based on the reference-input signal of the output as the second oscillator 13, carries out phase-locked detection to the output signal of displacement detecting circuit 7, exports the size in magnetic field and the phase data in magnetic field.The output of lock-in amplifier 21 is connected with signal transacting control part 17, and signal transacting control part 17, based on the size in magnetic field inputted and the phase data in magnetic field, carries out the process specified, and outputs to monitor 22 as view data.
In addition, obviously, concaveconvex shape data, the Distribution of Magnetic Field data of in signal transacting control part 17, carrying out signal transacting can not only be output to monitor 22, and can be exported by other the output unit such as printer.
[principle of work of magnetic force microscopy of the present invention]
The single armed beam of cantilever 2 to be one end be free end, has multiple mode of resonance.In order to obtain the relation of a resonance frequency f1 and secondary resonance frequency f2, the vibration amplitude η in the flexure direction of cantilever 2 is considered to the equation of motion of mechanics.
[numerical expression 1]
（1）
At this, the sectional area of cantilever 2 is A, bending moment is I, density is ρ, vertical elasticity coefficient is E.
At vibration amplitude η (x, t)=Y(x) cos(ω+α) in, when carrying out separating variables, for Y(x) formula (1) can be rewritten, become as follows.
[numerical expression 2]
（2）
Thus, Y(x) general solution become as shown in following formula (3).
[numerical expression 3]
（3）
At this, when considering the condition of stiff end, free end, the boundary condition of cantilever becomes as shown in following formula (4), (5).
[numerical expression 4]
（4）
[numerical expression 5]
（5）
Calculate by these boundary conditions are substituted into formula (2), thus obtain following formula (6)
[numerical expression 6]
（6）
At this, represent that the vibration equation formula of the constraint condition of vibrational system is as shown in following formula (7).
[numerical expression 7]
（7）
According to formula (7), when obtaining m, be m1=1.875104, m2=4.694091, corresponding with resonance frequency f1, a secondary resonance frequency f2 respectively.
In addition, according to formula (2), for angular frequency, the relation with m can be represented as following.
[numerical expression 8]
（8）
Thus, known ω's and resonance frequency f and m is square proportional.Therefore, a resonance frequency f1 becomes f2/f1=(m2/m1 with the ratio of secondary resonance frequency f2)
2=6.266893.In addition, when obtaining m and ω of high order further according to same calculating, one time resonance frequency is approximately 17.5 times with the ratio of three resonance frequencies, and one time resonance frequency is approximately 33.4 times with the ratio of four resonance frequencies.
Cantilever 2 has multiple intrinsic resonance frequency according to its shape, material, and these modes of resonance exist without interfering with each other mutually in same cantilever 2 simultaneously.Therefore, by the wave filter etc. of Additional provisions, thus the signal of these frequencies separately can be taken out.Accordingly, in magnetic force microscopy of the present invention, such as be set to secondary resonance frequency f2 by means of only by excitation frequency, the magnetic force microscopy of prior art added to the structures such as the wave filter of the signal taking out secondary resonance frequency f2, just can directly export the magnetic field data obtained by excitation signal.In this case, obviously, without the need to adding the frequency modulation (PFM) demodulation function based on characteristic frequency to Analytical system.
[work of magnetic force microscopy]
Refer again to Fig. 1, the work of magnetic force microscopy of the present invention is described in detail.
First, about the concavo-convex state estimating of the determined sample surfaces of magnetic force microscopy of the present invention, carry out as following.
The cantilever 2 being connected with the probe 1 of ferromagnetic in front end is fixed on piezoelectric element 3 in single armed beam-like.As above-mentioned, probe 1 is the probe being formed with CoCrPt alloy firm on silicon materials surface, and cantilever 2 is silicon systems.And cantilever 2 and probe 1 are integrated.By the first oscillator 4, piezoelectric element 3 is vibrated, cantilever 2 is vibrated with a resonance frequency f1.At this, a resonance frequency f1 of cantilever 2 is 58.306kHz.As above-mentioned, secondary resonance frequency f2 is 6.266893 × f1, therefore, in theory, becomes 365.397kHz, but, be 371.548kHz in actual measurement.Become f2/f1=6.37, deviation theory value is due to caused by different with coefficient of viscosity under secondary resonance frequency a resonance frequency a little.First oscillator 4 is made up of the function generator of more vairable (function generator).In addition, obviously, a resonance frequency f1 of cantilever at random can set according to the shape of cantilever, material etc.
By semiconductor laser 5, the vibrational state being detected cantilever 2 by the optical lever that the photodetector 6 of four segmentations and displacement detecting circuit are formed.The signal detected by displacement detecting circuit 7 is input to z-axis drive division 12 via bandpass filter 9, RMS-DC transducer 10 by error amplifier 11.Because also comprise the frequency component beyond a resonance frequency f1 in the signal exported from the displacement detecting circuit 7 of optical lever, so bandpass filter 9 and RMS-DC transducer 10 are for removing these frequency components.The signal and the reference voltage 11a that are input to error amplifier 11 compare, and are input to z-axis drive division 12 as being carried out negative feedback amplifying signal by error amplifier 11.When detecting according to the negative-feedback signal from error amplifier 11 that at z-axis drive division 12 amplitude of the front end of cantilever 2 diminishes, this z-axis drive division 12 drives the z scanner section of fine motion element 16, makes magnetic recording head 8 away from probe 1.On the contrary, when the amplitude of front end cantilever 2 being detected becomes large, drive the z scanner section of fine motion element 16, make magnetic recording head 8 close to probe 1.The xy scanner section of fine motion element 16 drives xy scanning driving part 18 by signal transacting control part 17, and the mensuration face of magnetic recording head 8 is moved in two-dimensional surface.Like this, keep with the surface configuration of the magnetic recording head 8 as the irregular determined sample of tool the distance that specifies, while scan the place of regulation, and measure the concaveconvex shape on magnetic recording head 8 surface.About measure concaveconvex shape, carry out signal transacting by the drive singal of z-axis drive division 12 and xy scanning driving part is input to signal transacting control part 17, thus using concaveconvex shape as visual information (hereinafter also referred to as configuration picture.) output to monitor 22.
In addition, although be illustrated the vibration amplitude of cantilever 2 front end is set to fixing control in above-mentioned, obviously, detect the phase place of vibration, the displacement of frequency by picture, they are set to fixing such control, also can measure the concaveconvex shape of determined sample.
Then, probe 1 and the distance of magnetic recording head 8, using the mode scan-probe 1 of the surface configuration along the magnetic recording head 8 as determined sample at said determination, remain fixing by magnetic force microscopy of the present invention, while measure magnetic field size and phase place.
Second oscillator 13 vibrates with the secondary resonance frequency f2 of cantilever 2, flows through alternating current at field coil 14, carries out excitation thus using secondary resonance frequency f2 to the magnetic recording head 8 as determined sample.The signal that displacement detecting circuit 7 by optical lever detects is input to lock-in amplifier 21.The output signal of the second oscillator 13 as with reference to signal, is carried out phase-locked detection to the output signal of displacement detecting circuit 7 by lock-in amplifier 21.The signal carrying out phase-locked detection is input to signal transacting control part 17.Signal transacting control part 17 carries out image procossing to the signal carrying out phase-locked detection, the Distribution of Magnetic Field on magnetic recording head 8 surface and phase data is outputted to monitor 22 and carries out visual.Like this, in phase-locked detection, because the frequency of Reference Signal is set to secondary resonance frequency f2, even if so the phase place change of the signal of a resonance frequency f1, also can not impact the phase place of the signal exported from lock-in amplifier 21.
In addition, in above-mentioned, by flowing through exciting current at the field coil 14 of the magnetic core being wound in the magnetic recording head 8 as determined sample, thus excitation being carried out to magnetic recording head 8, measuring Distribution of Magnetic Field and the phase place on surface.But, such as, when measuring the Distribution of Magnetic Field on magnetic recording media surface and the phase place of hard disk, be not attachedly on magnetic recording media have field coil.Therefore, need to import for the structure to determined sample applying external magnetic field at Analytical system.So, beyond the magnetic recording media as determined sample, the another small coil prepared for generation of external magnetic field.Such as, make toroid winding, this toroid winding uses well-known etching technique carry out composition to the substrate posting Cu paper tinsel on the substrate of regulation and form the toroid winding in the diameter of regulation and the ring current path of shape.Replace the field coil 14 of Fig. 1, the second oscillator 13, current-limiting resistance 15 are connected to this toroid winding.Then, make this toroid winding close in the mode covering the magnetic recording media becoming determined sample and be configured, making the magnetic flux produced from toroid winding pass through magnetic recording media.By like this, thus can utilize and flow through toroidal exciting current external magnetic field is applied to magnetic recording media, the Surface field measure of spread of magnetic recording media can be carried out by method similar to the above.
[measurement result of magnetic force microscopy]
As determined sample, employ the main pole part of magnetic recording head 8.Flow through the electric current of field coil 14 with the mode adjustment of the external magnetic field below the coercive force becoming the magnetic material of probe 1, and measure.Why adjust exciting current in the mode below the coercive force becoming probe 1, because as shown in Figure 2, flow through as the field coil 14 of input exciting current and can to maintain input and output as the output voltage of the displacement detecting circuit 7 of the optical lever exported linear.Be 5mA at the electric current flowing through field coil 14
rmswhen following, the magnetic confirming probe 1 can not magnetic saturation, can maintain input and output linear.
When measuring, in the main pole part of magnetic recording head 8, the vibration amplitude of cantilever 2 being remained fixing while scan determined sample surfaces, a line being carried out to the mensuration of configuration picture with the speed of 1Hz.Then, measuring the enterprising line scanning of identical sweep trace with configuration picture, the mensuration of Distribution of Magnetic Field is carried out.When measuring Distribution of Magnetic Field, making the vibration amplitude of a resonance frequency f1 decay to less than 20%, the height jog on magnetic recording head 8 surface being followed the trail of to (trace) is measured close to sample surfaces to-24nm from the height of reference field.
When the second oscillator 13 is with the secondary resonance frequency f2(371.548kHz of cantilever 2) when vibrating, the alternating current of secondary resonance frequency f2 flows through field coil 14.Like this, produce the AC magnetic field corresponding to exciting current from the main pole of magnetic recording head 8, the magnetic force caused by the interaction of the magnetic with probe 1 is applied to probe 1, and cantilever 2 vibrates with secondary resonance frequency f2.The output of displacement detecting circuit 7 is input to lock-in amplifier 21, the reference input of lock-in amplifier 21 is connected with the second oscillator 13.Like this, secondary resonance frequency f2=371.548kHz as with reference to frequency, is carried out phase-locked detection to the output signal of displacement detecting circuit 7 by lock-in amplifier 21, exports the Rcos θ component as the field signal of band phase information and Rsin θ component.Maximal value in order to the measurement range with detection signal that make lock-in amplifier 21 is mated thus is improved S/N ratio, and time constant (time constant) is set to 1ms.
By setting as described above, thus the mensuration of the configuration picture of the picture size of 256 pixel × 256 pixels and the Distribution of Magnetic Field of band phase information can be completed in about 9 minutes.In addition, when using the magnetic force microscopy of prior art of non-patent literature 1 ~ 5 to compare, minute is approximately 40 minutes.
Fig. 3 ~ Fig. 6 be using secondary resonance frequency f2=371.548kHz as the excitation frequency of magnetic recording head 8, in field coil 14, flow through 5mA as exciting current
rmsand carry out the result that measures.
Fig. 3 is the configuration picture measured with the magnetic force microscopy of said structure.Main pole 30 is written into shielding (shield) portion 31 and surrounds tripartite.The right side of write shielding part 31 is side shielding parts (side shield) 32.
Fig. 4 is the figure of the distribution of the magnetic field size only illustrated in the Distribution of Magnetic Field corresponding with the configuration picture of Fig. 3.Known, the magnetic field near main pole is strong, and in write shielding part 31, magnetic field dies down.
Fig. 5 is the figure that the magnetic force including the phase information corresponding with the configuration picture of Fig. 3 is shown, show side shielding part 32 partial magnetic field towards becoming the situation contrary with main pole.
Fig. 6 is figure Fig. 5 being carried out to 3-D view process, except the size of magnetic field, also by sense of vision explicitly show magnetic field towards being which direction relative to each several part.
As above-mentioned, in magnetic force microscopy of the present invention, together observing AC magnetic field with the concaveconvex shape of determined sample surfaces similarly is easily.Because with the secondary resonance frequency directly excitation cantilever arm 2 of more than hundreds of kHz, thus with to carry out about from 100Hz to 1kHz compared with the existing magnetic force microscopy that measures, can measuring at short notice.In addition, as above-mentioned explaining, because non-frequency of utilization modulation in the mensuration of Distribution of Magnetic Field, so, do not need to insert phaselocked loop in Analytical system, and, also can obtain Distribution of Magnetic Field data with high S/N ratio even without phaselocked loop.
Fig. 7 ~ Fig. 8 show magnetic force microscopy of the present invention with described in patent documentation 1, with unequal with the resonance frequency of cantilever and be the frequency of the integral multiple of the resonance frequency of cantilever to carry out the measurement result of the magnetic force microscopy of the excitation figure compared to sample.
Fig. 7 is the measurement result of the Distribution of Magnetic Field of the band phase information obtained by magnetic force microscopy of the present invention.The ratio of a resonance frequency f1 and secondary resonance frequency f2 is approximately 6.3 times as described above.In addition, in this mensuration, a resonance frequency f1 of cantilever is 67.904kHz, and secondary resonance frequency f2 is 428.366kHz.On the other hand, Fig. 8 is the measurement result in order to obtain the magnetic force microscopy employed described in patent documentation 1, and measurement result when using identical cantilever (f1=67.904kHz) to carry out excitation with the just in time electric current of 407.424kHz of frequency of 6 times of a resonance frequency to field coil to the determined sample identical with the determined sample of Fig. 7.Why excitation frequency being set to 6 times of a resonance frequency, is because this is the ratio 6.3 times of immediate integers with the frequency in magnetic force microscopy of the present invention.
As can be clear and definite according to Fig. 7 ~ Fig. 8, the sharpness of the view data obtained has larger difference.As the signal that can detect, be 10mV when magnetic force microscopy of the present invention, on the other hand, be 300 μ V in the magnetic force microscopy of the prior art of patent documentation 1 record.Therefore, magnetic force microscopy of the present invention can obtain the signal of large 33.3 times of the magnetic force microscopy of the prior art recorded than patent documentation 1.According to above content, not with the simple high frequency of the frequency of cantilever resonance frequency integral multiple to drive determined sample, but pass through the resonance frequency of the high order using cantilever intrinsic, thus the Q of Analytical system can be improved, by obtaining high gain, thus high S/N ratio can be realized.
In addition, in above-mentioned, although the resonance frequency used in magnetometry is set to secondary resonance frequency, be not limited to secondary resonance frequency, also the resonance frequency of three times or more high order can be used as the excitation frequency of determined sample.But, about the ratio of frequency, be approximately 17.5 times when three resonance frequencies, be 34.4 times when four times, become the frequency of more than 1MHz, therefore, should be noted that the response speed measuring sensitivity, Analytical system.
[variation 1]
In magnetic force microscopy of the present invention, the AC magnetic field produced from determined sample is detected with by the interaction of the ferromagnetic of probe 1 vibration as cantilever 2.In the above-described embodiment, the external magnetic field of the coercitive size of the ferromagnetic being no more than probe 1 is applied with.In external magnetic field below the coercive force of the magnetic of such probe 1, Distribution of Magnetic Field only detects the signal of Rcos θ component, and Rsin θ is zero substantially.At this, when use exceed the coercive force of the magnetic of probe 1 such external magnetic field time, the magnetization curve of magnetic has hysteresis (Hysteresis), consequently, is not only Rcos θ, and Rsin θ component can be detected.By measuring Rsin θ component, thus the stronger this point in magnetic field that only can not detect with Rcos θ component, which part can be measured clearly.
Fig. 9 is external magnetic field in order to be set to below coercive force and the exciting current of field coil 14 is set to 1mA
rmswhen (A) Rcos θ component and the measurement result of (B) Rsin θ component, the Rsin θ component of (B) does not almost observe change, represents that Rsin θ component exists (being zero) hardly.In addition, in order to improve the detection sensitivity of Distribution of Magnetic Field, probe 1 is measured up to the position of-34nm of the height of reference field close to the surface of determined sample.
The exciting current of field coil 14 is set to 5mA to be applied above the coercitive external magnetic field of probe 1 to determined sample by Figure 10 ~ Figure 12 in Fig. 10
rms, be set to 10mA in fig. 11
rms, be set to 20mA in fig. 12
rmswhen (A) Rcos θ component and the measurement result of (B) Rsin θ component.
As respectively schemed shown in (A) in Fig. 9 ~ 12, about Rcos θ component, although intensity is different, almost there is no difference.On the other hand, shown in Ru Getu (B), known about Rsin θ component, signal detected along with in main pole 30 with the slotted section of write shielding part 31, exciting current increases, and external magnetic field becomes large, and the intensity of its signal also becomes large.Specifically, known, at 5mA
rmstime, become negative near main pole central part, at 10mA
rmsand 20mA
rmstime, become negative in main pole entirety.And then, at 10mA
rmsand 20mA
rmstime, the magnetic distribution image of the cleat shape reflecting main pole can be observed in Rsin θ picture.
Like this, when the dynamic range deficiency only measured by the situation of the Distribution of Magnetic Field information of Rcos θ component, by being applied above the coercitive external magnetic field of probe 1, thus more detailed Distribution of Magnetic Field information can be obtained by adding the change of Rsin θ component.
In addition, about the probe 1 used in this variation, in order to make spatial resolution become good, preferably using by controlling the face that covered by magnetic and physical dimension is made little probe.Such as, preferably the fore-end of the probe 1 be made up of carbon nano-tube be coated with magnetic probe, make needle-like magnetic carry out the probe etc. of crystal growth in the front end of probe 1.
[variation 2]
When being applied above the coercitive AC magnetic field of the probe be connected with cantilever front end, when magnetic field exceedes the coercive force of the ferromagnetic forming probe, just to cantilever action gravitation.This situation illustrates: under the frequency of the twice of the frequency of applied AC magnetic field, between cantilever and determined sample, produce gravitation.Therefore, by carrying out excitation with the determined sample of 1/2 couple of secondary resonance frequency, thus the magnetometry in the frequency gravity model equal with secondary resonance frequency can be carried out.
Figure 13 is the block diagram of the structure example of the magnetic force microscopy that other variation of the present invention is shown.Relative to the structure of above-mentioned variation 1, difference is, is the frequency of 1/2 of the secondary resonance frequency f2 of cantilever 2 to the frequency of the AC magnetic field that determined sample applies.
In the same manner as the above-mentioned situation shown in Fig. 1, the cantilever 2 being connected with the probe 1 with ferromagnetic in front end is fixed on piezoelectric element 3 in single armed beam-like.Probe 1 is the probe being formed with CoCrPt alloy firm on silicon materials surface.Magnetic is not limited to CoCrPt, and can be other Co class alloy such as CoCr alloy, CoPt alloy, also can be other magnetic, such as ferrite, Fe, Ni, FePt, their alloy or permalloy etc., and this is also identical with the situation of Fig. 1.Such as, can be the PPP-MFMR etc. that NANOWORLD society manufactures, coercive force be in this case about 300Oe.
First oscillator 4 is connected with piezoelectric element 3 in the fixing side of cantilever 2.First oscillator 4 drives piezoelectric element 3, and cantilever 2 is vibrated with a resonance frequency.
By semiconductor laser 5, by the photodetectors 6 of four segmentations and the optical lever that forms of displacement detecting circuit 7, in order to detect the vibrational state of cantilever 2, detecting with photodetector 6 laser reflected at cantilever 2 and carrying out light-to-current inversion.Then, the amplitude of detected laser and the change of phase place is detected with displacement detecting circuit 7.In addition, in the same manner as the situation of Fig. 1, carry out the displacement detecting of cantilever 2, be not limited to optical lever, also can use the mode utilizing other interference light, the mode etc. of such as being undertaken by the focus error detection employing Optical fibre interferometric or prism, can also use the mode beyond interference light, such as, employ the mode of magnetoresistive element or employ the mode etc. of piezoelectric element.
The output of displacement detecting circuit 7 is connected with the bandpass filter 9 be connected in series, RMS-DC transducer 10, and the reversion input via error amplifier 11 is connected with z-axis drive division 12.Reference voltage 11a is connected with in the non-inverting input of error amplifier 11.And the output of error amplifier 11 is connected with z-axis drive division 12, the output of z-axis drive division 12 is connected the z scanner portion driving fine motion element 16 with fine motion element 16.Z scanner portion is driven in the vertical direction by the mensuration face of z-axis drive division 12 relative to the magnetic recording head 8 as determined sample.
Signal transacting control part 17 is connected with the xy scanner portion of fine motion element 16 and coarse motion mechanism 20 respectively via xy scanning driving part 18 and coarse motion mechanism drive part 19.The output of z-axis drive division 12 and xy scanning driving part 18 is also connected with signal transacting control part 17, and the concaveconvex shape data of signal transacting control part 17 to determined sample carry out signal transacting, output to monitor 22 as view data.
Magnetic recording head 8 as determined sample is fixed on and carries out on the upper surface of fine motion element 16 of the location of determined sample with nm magnitude in all directions of xyz axle.Fine motion element 16 be fixed in all directions of xyz axle, carry out the location of determined sample and the coarse motion mechanism 20 of scanning in a wide range upper surface on.Fine motion element 16 and coarse motion mechanism 20 control distance and the position on the front end of probe 1 and the surface of determined sample via z-axis drive division 12, xy scanning driving part 18, coarse motion mechanism drive part 19.In addition, fine motion element 16 is such as formed by piezoelectric element, according to the voltage applied by z-axis drive division 12 grade, controls the direction and the displacement that carry out displacement.On the other hand, coarse motion mechanism is by the driving means of machinery, and such as Motor Control carries out the position control measuring platform.
Second oscillator 13a exports the frequency of 1/2 of the secondary resonance frequency f2 of cantilever 2.The output of the second oscillator 13a is connected with the field coil 14 of the magnetic core of the magnetic recording head 8 be wound on as determined sample.Another terminal of field coil 14 is via current-limiting resistance 15 ground connection.
3rd oscillator 13b exports the frequency of the secondary resonance frequency f2 of cantilever 2.The output of the 3rd oscillator 13b is connected with the reference input of lock-in amplifier 21.The output of the displacement detecting circuit 7 of optical lever is connected with lock-in amplifier 21.Lock-in amplifier 21, based on the reference-input signal of the output as the second oscillator 13a, carries out phase-locked detection to the output signal of displacement detecting circuit 7, exports the size in magnetic field and the phase data in magnetic field.The output of lock-in amplifier 21 is connected with signal transacting control part 17, and the magnetic field size of signal transacting control part 17 based on input and the phase data in magnetic field, carry out the process specified, and output to monitor 22 as view data.
In addition, also can via the frequency multiplier output of the second oscillator 13a being set to the frequency of twice, the reference frequency as lock-in amplifier 21 inputs the signal of the frequency equal with the secondary resonance frequency of cantilever 2.Or, also can use in the excitation of determined sample and will become the signal of the frequency of (1/2) f2 as the signal being input to the secondary resonance frequency f2 of lock-in amplifier 21 with reference to frequency by frequency divider.
The result of the structure determination with Figure 13 is shown at Figure 14 ~ Figure 17.As concrete condition determination, with the scope excitation cantilever arm 2 of a resonance frequency f1 ~ 67.481kHz, measure configuration picture in the same manner as the situation of Fig. 1.At this, such as, the vibration amplitude of cantilever 2 is set to 0.5Vpp.
Then, in order to obtain Distribution of Magnetic Field, in the main pole part of the magnetic recording head 8 as determined sample, the distance of probe 1 and magnetic recording head 8 is controlled while scan the vibration amplitude of cantilever 2 to be remained fixing mode.At this, such as, make the vibration amplitude of cantilever 2 drop to 0.1Vpp, make the position in the centre of oscillation be close to the distance of 8nm from sample surfaces.Because the secondary resonance frequency f2 of the cantilever 2 in this situation is 424.324kHz, so as the frequency of magnetic recording head 8 being carried out to excitation, be set to the 212.162kHz of the frequency of its 1/2.
Like this, by optical lever using the frequency of the secondary resonance frequency f2 of cantilever 2 as reference input signal, lock-in amplifier 21 is used to measure Distribution of Magnetic Field picture.
Such as, control the distance between probe 1 and determined sample, scan with each line 1Hz, measure surface configuration and store.Then, keep the fixed range with surface along the surface configuration stored, measure Distribution of Magnetic Field picture.Like this, in the same manner as the situations such as above-mentioned Fig. 1, it is about 9 minutes as the configuration picture of 256 pixel × 256 pixels and the minute of Distribution of Magnetic Field picture.
As shown in Figure 14 A, Figure 14 C, the 1mA below the coercive force no matter exciting current being set to the ferromagnetic of probe 1
rms, be still set to and exceed coercitive 20mA
rms, identical configuration picture can be obtained.On the other hand, as shown in Figure 14B, as 1mA exciting current being set to below coercive force
rmstime, almost can't detect whatever as Distribution of Magnetic Field picture.As shown in fig. 14d, when exciting current is set to 20mA
rmstime, the shape of the front end of the head in Wedge-shaped can be confirmed as Distribution of Magnetic Field picture.
In order to confirm spatial resolution, the state of variation 1 is shown at Figure 15 A ~ C, namely, coercitive AC magnetic field is applied above to determined sample, the frequency of AC magnetic field is set to the frequency equal with secondary resonance frequency f2 again measure, obtains the state of the above-mentioned Distribution of Magnetic Field picture again measured.As illustrating in variation 1, as Rsin θ picture, generation direction, magnetic field can be comprised and measure.
Figure 16 A is the figure of the cross section profile at the dotted line position that Figure 14 D is shown, is using the benchmark (x=0nm) of the downside of Figure 14 D as distance, describes the figure of the voltage proportional with the intensity in magnetic field.By means of magnetic pole, near approximate centre, the intensity in (x=530nm) magnetic field becomes large.By carrying out Fourier transform to the cross section profile of Figure 16 A, obtain data as shown in fig 16b.By these Fourier transform data, known in spatial frequency kx=95 μm
-1above, signal intensity is-37dB, is roughly fixed value.At this, signal intensity-37dB is the thermonoise not relying on spatial frequency.On the other hand, spatial frequency kx=μm
-1time following, because there is the signal intensity larger than thermonoise, so spatial frequency kx=95 μm
-1with can not to bury by thermonoise and the maximum spatial frequency that can detect is corresponding.Therefore, by getting the inverse of this maximum spatial frequency, thus can estimate minimum spatial resolution, the minimum value of spatial resolution when Figure 16 B can be set to 10.52nm.
It is more than spatial resolution when excitation being carried out to determined sample with the frequency of 1/2 of the secondary resonance frequency f2 of cantilever 2, but, about spatial resolution when carrying out excitation with the secondary resonance frequency f2 of cantilever 2, also similarly can estimate according to the cross section profile of the dotted line of Figure 15 A ~ C.Figure 17 A ~ C is figure cross section profile corresponding with Figure 15 A ~ C respectively being carried out to Fourier transform.According to Figure 17 B, for Rcos θ, the minimum value of the spatial resolution that the maximal value of the spatial frequency buried according to the thermonoise of not determined system is obtained is 20.41nm.In addition, according to Figure 17 C, be 17.85nm for Rsin θ.
When the coercive force exceeding ferromagnetism probe carries out excitation to determined sample, by carrying out excitation with the frequency of 1/2 of the secondary resonance frequency f2 of cantilever, thus with carry out the situation of excitation with secondary resonance frequency f2 compared with, Distribution of Magnetic Field picture can be measured with the spatial resolution about twice.
In above-mentioned, although the excitation frequency of cantilever 2 to be set to a resonance frequency of cantilever 2, the excitation frequency of determined sample is set to the frequency of 1/2 of the secondary resonance frequency of cantilever 2, but, by guaranteeing the broad in band, precision etc. of Analytical system, thus also can use respectively than the resonance frequency of their high orders.Such as, the excitation frequency of cantilever 2 can be set to secondary resonance frequency, the excitation frequency of determined sample be set to three resonance frequencies.Or, make the excitation frequency of cantilever 2 remain a resonance frequency, the excitation frequency of determined sample is set to three times or its above high order resonance frequency 1/2 frequency.
In addition, in the same manner as the situation of the structure example of Fig. 1, also can replace being wound on the field coil 14 as on the magnetic core of the magnetic recording head 8 of determined sample, and use toroid winding.Toroid winding such as by being formed with under type, that is, uses well-known etching technique to carry out composition to the substrate posting Cu paper tinsel on the substrate of regulation, forms the diameter of regulation and the ring current path of shape.Toroid winding connecting the second oscillator 13a, current-limiting resistance 15, making this toroid winding close to being configured in the mode covering the magnetic recording media becoming determined sample, make the magnetic flux produced from toroid winding pass through magnetic recording media.By like this, thus can utilize and flow through toroidal exciting current external magnetic field is applied to magnetic recording media, method similar to the above can be adopted to carry out the Surface field measure of spread of magnetic recording media.
Magnetic force microscopy described above is for illustration of object lesson, and obviously, the present invention is not only defined in above-mentioned embodiment, is not departing from the scope of main idea of the present invention, can carry out various change.
The explanation of Reference numeral
1: probe; 2: cantilever; 3: piezoelectric element; 4: the first oscillators; 5: laser instrument;
6: light receiving element; 7: displacement detector; 8: magnetic recording head; 9: bandpass filter; 10:RMS-DC transducer; 11: error amplifier; 11a: reference voltage; 12:z axle drive division; 13, the 13a: the second oscillator; 13b: the three oscillator; 14: field coil; 15: current-limiting resistance; 16: fine motion element; 17: signal transacting control part; 18:xy scanning driving part; 19: coarse motion mechanism drive part; 20: coarse motion mechanism; 21: lock-in amplifier; 22: monitor 30: main pole; 31: write shielding; 32: side shields.
Claims (14)
1. a magnetic force microscopy, is characterized in that, possesses:
Cantilever, has the probe be made up of magnetic or is coated with the probe that the probe of magnetic or film form the body that is magnetic in front end;
First oscillator, encourages above-mentioned cantilever with the first resonance frequency of this cantilever;
Displacement detector, detects the displacement of above-mentioned cantilever front end;
Fine motion element, is fixed on upper surface by sample, makes above-mentioned probe close relative to this sample, separately or make the movement that locates;
Drive division, drives above-mentioned fine motion element;
Second oscillator, carries out excitation with the second resonance frequency of above-mentioned cantilever to above-mentioned sample; And
Tiny signal amplifier, inputs the displacement signal that exports from above-mentioned displacement detector and the reference signal as above-mentioned second resonance frequency,
Above-mentioned drive division, based on the displacement of the above-mentioned cantilever front end detected by above-mentioned displacement detector and above-mentioned first resonance frequency, by driving above-mentioned fine motion element to make above-mentioned probe close or separately relative to above-mentioned sample, thus measures the concaveconvex shape of this sample,
Above-mentioned tiny signal amplifier, based on the concaveconvex shape of above-mentioned sample, upper displacement signal and above-mentioned reference signal, generates the output corresponding to the magnetic field of above-mentioned sample surfaces.
2. magnetic force microscopy according to claim 1, wherein,
Above-mentioned first resonance frequency is a resonance frequency of above-mentioned cantilever,
Above-mentioned second resonance frequency is the higher order resonant frequencies of more than the secondary of above-mentioned cantilever.
3. magnetic force microscopy according to claim 2, wherein,
Above-mentioned higher order resonant frequencies is secondary resonance frequency.
4. magnetic force microscopy according to claim 1, wherein,
Above-mentioned displacement detector is optical lever, and above-mentioned optical lever comprises:
Laser output portion, Output of laser;
Light receiving element, inputs the reflected light being carried out at above-mentioned cantilever by the laser exported from above-mentioned Laser output portion reflecting; And
Signal processing part, is carried out the electric signal converted, thus measures the displacement of above-mentioned cantilever at above-mentioned light receiving element by process.
5. magnetic force microscopy according to claim 1, is characterized in that,
Above-mentioned second oscillator, via with the coil of the mode covering above-mentioned sample close to configuration, carries out excitation with above-mentioned second resonance frequency to above-mentioned sample.
6. magnetic force microscopy according to claim 1, wherein,
Above-mentioned tiny signal amplifier is lock-in amplifier.
7. magnetic force microscopy according to claim 1, is characterized in that,
The above-mentioned sample of above-mentioned second a pair of oscillators carries out excitation, makes it the external magnetic field of more than the coercive force of the magnetic producing above-mentioned probe.
8. a magnetic force microscopy, is characterized in that, possesses:
Cantilever, has the probe be made up of magnetic or is coated with the probe that the probe of magnetic or film form the body that is magnetic in front end;
First oscillator, encourages above-mentioned cantilever with the first resonance frequency of this cantilever;
Displacement detector, detects the displacement of above-mentioned cantilever front end;
Fine motion element, is fixed on upper surface by sample, makes above-mentioned probe close relative to this sample, separately or make the movement that locates;
Drive division, drives above-mentioned fine motion element;
Second oscillator, carries out excitation with the frequency of 1/2 of the second resonance frequency of above-mentioned cantilever to above-mentioned sample; And
Tiny signal amplifier, inputs the displacement signal that exports from above-mentioned displacement detector and the reference signal as above-mentioned second resonance frequency,
Above-mentioned drive division, based on the displacement of the above-mentioned cantilever front end detected by above-mentioned displacement detector and above-mentioned first resonance frequency, makes by driving above-mentioned fine motion element above-mentioned probe close or separately relative to above-mentioned sample, thus measures the concaveconvex shape of this sample,
The above-mentioned sample of above-mentioned second a pair of oscillators carries out excitation, makes it the external magnetic field of more than the coercive force of the magnetic producing above-mentioned probe,
Above-mentioned tiny signal amplifier, based on the concaveconvex shape of above-mentioned sample, upper displacement signal and above-mentioned reference signal, generates the output corresponding to the magnetic field of above-mentioned sample surfaces.
9. magnetic force microscopy according to claim 8, wherein,
Above-mentioned first resonance frequency is a resonance frequency of above-mentioned cantilever,
Above-mentioned second resonance frequency is the higher order resonant frequencies of more than the secondary of above-mentioned cantilever.
10. magnetic force microscopy according to claim 9, wherein,
Above-mentioned higher order resonant frequencies is secondary resonance frequency.
11. 1 kinds of high spatial resolution magnetic field measuring methods, is characterized in that having:
Be activated at front end by the first oscillator with the first resonance frequency of cantilever and there is this cantilever that the probe be made up of magnetic or the probe being coated with magnetic or film form the probe of the body that is magnetic, based on displacement and first resonance frequency of this cantilever front end, by making this probe close or separately thus measure the step of the concaveconvex shape of this sample relative to sample; And
With the second resonance frequency of above-mentioned cantilever, excitation is carried out to above-mentioned sample by the second oscillator, based on the concaveconvex shape of said determination, the displacement of this cantilever front end and this second resonance frequency, generate the step of the output corresponding to the magnetic field of above-mentioned sample surfaces.
12. high spatial resolution magnetic field measuring methods according to claim 11, wherein,
Above-mentioned first resonance frequency is a resonance frequency of above-mentioned cantilever,
Above-mentioned second resonance frequency is the higher order resonant frequencies of more than the secondary of above-mentioned cantilever.
13. high spatial resolution magnetic field measuring methods according to claim 12, wherein,
Above-mentioned higher order resonant frequencies is the secondary resonance frequency of above-mentioned cantilever.
14. 1 kinds of high spatial resolution magnetic field measuring methods, is characterized in that having:
Be activated at front end by the first oscillator with the first resonance frequency of cantilever and there is this cantilever that the probe be made up of magnetic or the probe being coated with magnetic or film form the probe of the body that is magnetic, based on displacement and first resonance frequency of this cantilever front end, by making this probe close or separately thus measure the step of the concaveconvex shape of this sample relative to sample; And
By the second oscillator with 1/2 of the second resonance frequency of above-mentioned cantilever frequency excitation is carried out to above-mentioned sample, based on the concaveconvex shape of said determination, the displacement of this cantilever front end and this second resonance frequency, generate the step of the output corresponding to the magnetic field of above-mentioned sample surfaces
The above-mentioned sample of above-mentioned second a pair of oscillators carries out excitation, makes it the external magnetic field of more than the coercive force of the magnetic producing above-mentioned probe.
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| CN1672011A (en) * | 2002-07-04 | 2005-09-21 | 布里斯托尔大学 | Scanning probe microscope |
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| Publication number | Publication date |
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| CN103443632A (en) | 2013-12-11 |
| JP2012198192A (en) | 2012-10-18 |
| WO2012121308A1 (en) | 2012-09-13 |
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