JP2007271465A - Magnetic field distribution measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic field distribution measuring instrument that has high resolution and that simplifies the position control of a probe. <P>SOLUTION: The magnetic field distribution measuring instrument comprises the probe having a thin-film magnetometric sensor for detecting magnetic field distribution very close to a measured object as an output signal of voltage or current, an actuator for one-dimensionally translation-scanning the probe in the thickness direction of the thin-film magnetometric sensor, a rotating mechanism for making the measured object rotate in the horizontal plane, an angle sensor for detecting the rotation angle of the measured object, and a magnetic field distribution reconstructing means for reconstructing the magnetic field distribution, based on the output signal from the probe, the position signal of the probe output from the actuator, and a rotation angle signal output from the angle sensor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic field distribution measuring apparatus capable of measuring a magnetic field leaking into a space from a magnetic component such as a magnetic head or a magnetic disk with high resolution.

In recent years, the density of various magnetic recording devices such as hard disks (HDD) and nonvolatile magnetic memories (MRAM) has been rapidly increasing. In R & D sites such as HDDs, there are many requests to evaluate the minute magnetization distribution of recording media of various devices and the magnetic field distribution around the minute magnetic head (see Non-Patent Documents 1 and 2).
For the magnetic field measurement technology being studied, a transmission electron microscope is applied to reconstruct a magnetic field distribution from Lorentz deflection that occurs when an electron beam passes through a magnetic field (see Non-Patent Documents 1 and 3). ), Magnetic force microscopes using magnetized nanoprobes (see Non-Patent Documents 4 and 5), scanning Hall element microscopes and the like (see Non-Patent Document 6).
In the method using an electron beam, in order to avoid the collision of deflected electrons with the sample, it is difficult to measure near the sample (up to 50 nm) and the resolution is about 100 nm to 200 nm. There is.

  On the other hand, magnetic force microscopes and scanning Hall element microscopes are easier to handle and can be used at various development sites than using electron beams, but magnetic force microscopes can produce needle-like probes with fine tips. There are problems that it is difficult, Hall element microscopes have a resolution of 1 μm, and that both require precise control of the probe.

At present, magnetic sensors using thin film technology are widely used including HDD heads (see Non-Patent Documents 7 and 8). Thin film magnetic sensors include those using an induced electromotive force and those using a magnetoresistive effect (MR effect). The MR effect is a phenomenon in which the resistance of the element changes due to an external magnetic field. Anisotropic magnetoresistance in read head of the HDD using the MR effect (Anisotropic Magnetoresistive) head, and the like giant magnetoresistance (G iant M agneto r esistive) head. The GMR head, which is the mainstream of current HDD read heads, has a film thickness of 10 nm or less, and reads the magnetization distribution on the disks arranged at intervals of several tens of nm.
Co-authored by H. Suzuki, T. Shimakura, K. Itoh, K. Nakamura, “Magnetic Head Field Over the Air” -Bearing surface as a visualized by the projection of a patterned electron beam '', Eye Triple Transactions on Magnetics (IEEE TRANSACTIONS ON MAGNETICS), 2000 Part 1, Volume 36, Issue 5, p3614-3617 Co-authored by CH.Back, J.Heidmann, and J.McCord, “Time Resolved Car Microscopy: Magneticization Dynamics in Thin Film”・ Time resolved Kerr microscopy: Magnetization dynamics in thin filmwrite heads ”, IEEE TRANSACTIONS ON MAGNETICS, 1999 Part 1, Vol. 35, No. 2, p. 637 -642 Co-authored by K. Nakamura, T. Shimakura, and H. Suzuki, “Magnetic Field Measurement for Analysis of Gigahertz Response in Spirit”・ Head-using electron beam tomography (Magnetic field measurement for analysis of GHz response in SPT headusing electron beam tomography), J. MAGNETISM AND MAGNETIC MATERIALS, 2005 Year, Vol. 287, p333-338 H. Kuramochi, T. Uzumaki, M. Yasutake, A. Tanaka, H. Akinaga, H. Yokoyama (H Yokoyama), "A magnetic force microscope using CoFe-coated carbon nanotubeprobes", NANOTECHNOLOGY, 2005 , Volume 16, Issue 1, p24-27 Kuramochi H., Akinaga H., Semba Y., Kijima N., Uzumaki T., Yasutake M ), Tanaka A., and Yokoyama H., "CoFe-coated carbon nanotube probes (CoFe-coated carbon nanotube probes) for magnetic force microscope), Japanese Journal of Applied Physics, 2005, 44, 4A, p2079-2082 Fukumura Tomoaki, Hasegawa Tetsuya: Application of scanning probe microscopes to magnetic semiconductors and supergiant magnetoresistive materials, Surface Science, 2002, Vol. 23, No. 4, p233-238 Co-authored by B. Vasic and EMKurtas, “Coding and signal processing for magnetic recording systems”, CRC・ CRC Press LLC, 2005, Sec.1 / Sec.2 RLComstock, `` Introduction to Magnetism and Magnetic Recording '', John Wiley & Sons. Inc. ), 1999, p353-417

  In view of the problems of the prior art, the present invention provides a high resolution (10 nm or less) by using a thin film magnetic sensor as an alternative to a method using an electron beam or a magnetized nanoprobe. It is another object of the present invention to provide a magnetic field distribution measuring apparatus in which the position control of the probe is simplified.

  The present invention relates to a magnetic field distribution measuring apparatus that measures the distribution of a magnetic field that leaks into the space from an object to be measured. A probe composed of a thin film magnetic sensor for detecting the probe, an actuator for causing the probe to perform a one-dimensional translational scan in the film thickness direction of the thin film magnetic sensor, a rotating mechanism for rotating the measurement target in a horizontal plane, and the measurement target Reconstructing the magnetic field distribution based on an angle sensor that detects the rotation angle of an object, an output signal from the probe, a position signal of the probe output from the actuator, and a rotation angle signal output from the angle sensor This is achieved by a magnetic field distribution measuring apparatus comprising a magnetic field distribution reconstructing means.

  In addition, the object of the present invention is to provide a probe having a multilayer structure in which two or more thin film magnetic sensors for detecting a magnetic field distribution in the vicinity of the object to be measured as a voltage or current output signal are stacked, and the object to be measured. A rotation mechanism that rotates the measurement object in a horizontal plane, an angle sensor that detects a rotation angle of the measurement object, an output signal from each probe, a position signal of each probe, and an output from the angle sensor This is achieved by a magnetic field distribution measuring device comprising a magnetic field distribution reconstruction means for reconstructing the magnetic field distribution based on a rotation angle signal.

  Furthermore, the object of the present invention is to detect an actuator for one-dimensional translation of the object to be measured in a predetermined direction in a horizontal plane and a magnetic field distribution in the vicinity of the object to be measured as an output signal of voltage or current. A probe group in which a plurality of thin film magnetic sensors are arranged in the predetermined direction in the horizontal plane at predetermined intervals and at different angles, output signals from the probes of the probe group, position information of the probes, and probes And a magnetic field distribution reconstructing means for reconstructing the magnetic field distribution based on a tilt angle of the measured object and a position signal of the measurement object output from the actuator. The

According to the magnetic field distribution measuring apparatus using the thin film magnetic sensor according to the present invention, the thin film magnetic sensor is translationally scanned in a one-dimensional direction on the rotating sample to obtain measurement data at various rotation angles and translation positions. In addition, since the magnetic field distribution is reconstructed from the obtained measurement data using a CT algorithm generally used, a resolution equivalent to the film thickness (10 nm or less) of the thin film magnetic sensor can be obtained.
In addition, GMR heads used as thin-film magnetic sensors do not require precise position control in the longitudinal direction by making the longitudinal direction of the head sufficiently large with respect to the sample, and are needle-shaped used in conventional magnetic force microscopes. This eliminates the need for two-dimensional precise position control in the horizontal plane as in the case of this probe, and has an effect of simplifying the position control of the probe.
On the other hand, since the angle is a dimensionless number, its control is relatively easy. Therefore, when a thin film magnetic sensor is used, the number of dimensions that require precise nanoscale control can be reduced by one dimension. This is a great advantage in constructing an actual measurement system.

The magnetic field distribution measuring apparatus according to the present invention uses a thin film magnetic sensor used in an HDD or the like as a probe, rotates the sample in a horizontal plane, and the thickness of the thin film magnetic sensor near the sample rotates. Measurement data is obtained by performing a one-dimensional translation scan in the vertical direction. The magnetic field distribution is reconstructed from measurement data obtained by scanning at various sample rotation angles and translational positions.
FIG. 1 is a block diagram showing a configuration of a magnetic field distribution measuring apparatus according to the present invention.
A probe comprising a thin film magnetic sensor for detecting a magnetic field distribution in the vicinity of the object to be measured as a voltage signal (ΔV), and an actuator for performing a one-dimensional translational scan in the film thickness direction of the thin film magnetic sensor via a support member; A rotation mechanism comprising a turntable and a motor for rotating the object to be measured in a horizontal plane, an angle sensor for detecting the rotation angle of the object to be measured, a voltage signal (ΔV) from the probe, and output from the actuator Magnetic field distribution reconstruction means for reconstructing the magnetic field distribution based on the position signal (X) of the probe and the rotation angle signal (θ) output from the angle sensor.
In this embodiment, a constant current is supplied to the thin film magnetic sensor, and the resistance change due to the magnetic field is extracted as a voltage change signal (ΔV) and used for the calculation of the reconstruction of the magnetic field distribution. The change in resistance due to the magnetic field may be applied and taken out as a current change signal (ΔI) and used for the calculation of the reconstruction of the magnetic field distribution.
A GMR head is preferred as the thin film magnetic sensor. As the actuator, a piezoelectric element that is deformed by voltage application can be used.
As the magnetic field distribution reconstruction means, a personal computer installed with a program based on a predetermined reconstruction algorithm can be used. Moreover, the display of a personal computer can be used as a display means for reconstructed magnetic field distribution. As a reconstruction algorithm, an X-ray CT algorithm (Computed Tomography) that is generally widely known can be used. Conventionally, the resolution limited by the representative length of the sensor can be made equal to the film thickness of the thin film sensor by the method according to the present invention. Since the proposed method can use the measurement technology that has been remarkably advanced in the field of HDD as it is, it can expect high-resolution measurement easily and inexpensively.
This section describes the details of the method for obtaining the magnetic field distribution with the resolution equivalent to the film thickness of the thin film sensor using the thin film magnetic sensor currently used in the HDD. First, forward analysis for obtaining simulated measurement data obtained by scanning a thin film magnetic head on a sample is shown, and then a technique for reconstructing the magnetic field distribution from the simulated measurement data is shown. Finally, the result of numerical simulation of this method is shown.

[1. Principle of observation using thin film magnetic sensor)
Various thin film magnetic sensors can be used. In the present invention, the principle will be described below using the GMR head, which is the mainstream of HDD read heads, as an example.
(1.1 Explanation of GMR head)
A brief description of the HDD read head using the giant magnetoresistive effect (GMR) will be given. An enlarged schematic view of the HDD head is shown in FIG. FIG. 2 shows a state in which a perpendicular magnetic recording type writing head and a reading GMR head float in the vicinity of the disk and read and write magnetic data.
An enlarged schematic view of the GMR head of FIG. 2 is shown in FIG. The GMR head has a multilayer structure in which a nonmagnetic metal layer (Spacer) is sandwiched between two ferromagnetic materials. The GMR effect is a phenomenon in which the resistivity of a multilayer film changes when the magnetization directions of two ferromagnetic materials are parallel and antiparallel. When used as an HDD read head, the magnetization direction of one of the two ferromagnets (Pinned layer) is fixed, and the magnetization direction of the other (Free layer) changes due to the magnetic field from the disk. It has become. A constant current is passed through the multilayer film, and the resistance change due to the magnetic field is observed as a voltage change. The GMR head is currently several nanometers (nm) thick and several hundred nanometers wide, and there is a trend toward further miniaturization in order to further increase the density of HDDs.
In the HDD, as shown in FIG. 2, since the writing head and the reading head are elongated, the magnetization on the disk has a strip-like distribution. Although a high recording density is obtained in the thickness direction of the strip, the recording density in the longitudinal direction is lowered. On the other hand, when a GMR head is used as a probe, high resolution can be obtained in the thickness direction of the GMR head. There is a problem that the resolution in the longitudinal direction is limited by the width of the head.

(1.2 Observation method)
Details of the method of using the GMR head as a probe of the magnetic field distribution measuring apparatus are shown. A sample having a magnetization distribution is scanned with a GMR head as shown in FIG. 4 to obtain measurement data. The sample is rotated in the horizontal plane, and the GMR head is scanned one-dimensionally in the thickness direction. The current value flowing through the head is kept constant, and the resistance change due to the magnetic field from the sample is observed as a voltage change at both ends of the head. A simultaneous equation with the magnetic field distribution as an unknown is constructed from a plurality of observation amounts obtained at various rotational angles and translational positions.
Since the structure of the simultaneous equations is the same as that handled by the X-ray CT method, various reconstruction algorithms of the existing X-ray CT method can be used for solving the equations. The resolution of the magnetic field distribution obtained by solving the simultaneous equations depends on the film thickness of the GMR head. When the film thickness is thin, the resolution obtained is improved, and when it is thick, the resolution is lowered. As the film thickness increases, the simultaneous equations become ill-conditioned, resulting in a decrease in resolution.

電圧変化g(X,θ)が磁界分布ｈ(x,y)の積分値として近似できる理由は後述（段落００１８）する。 (1.3 Mathematical model)
The following is a mathematical model that uses a GMR head as a probe to scan translation and rotation and observe magnetic field changes from the sample as voltage changes. FIG. 5 is a view of FIG. 4 viewed from above. The head performs translational scanning in the X-axis direction in the XY coordinate system, and the sample rotates by θ around the origin of the XY coordinate system. The xy coordinate system is a coordinate system fixed to the sample. Both the z-axis and the Z-axis are taken vertically upward from the sample surface. Assume that the Z-axis component of the magnetic field distribution at a certain distance from the sample in the Z-axis direction is h (x, y), and the voltage change observed at both ends of the head is g (X, θ). The head scans the sample rotated by θ in the X-axis direction, and the voltage change g (X, θ) is observed. Since the film thickness of the head is thin, the voltage change g (X, θ) can be obtained as an integral value in the Y direction of the magnetic field distribution h (x, y) at the lower end surface of the head as shown in Expression (1).

The reason why the voltage change g (X, θ) can be approximated as an integral value of the magnetic field distribution h (x, y) will be described later (paragraph 0018).

を再構成する手法を示す。
g(X,θ)から

の再構成には、一般的に広く利用されているＸ線ＣＴ法を利用することができる。ＣＴ法の手法にはFBP法（Filtered Backprojection）、CBP法（Convolution Backprojection）、EL−ME法等様々な手法があるが、ここでは例としてFBP法の適用例について説明する。
磁界分布ｈ(x,y)の２次元フーリエ変換H(ξ，η)は式（4）のように表される。

ここで、ξ＝ωcosθ，η＝ωsinθとして極座標(ω，θ)で表すと次式となる。

さらに、式（5）を変形すると、以下のようになる。

式（10）は、磁界分布の２次元フーリエ変換H(ωcosθ，ωsinθ)と観測値の1次元フーリエ変換G(ω，θ)が等しいことを表している。H(ξ，η)の２次元フーリエ逆変換は極座標(ω，θ)で表すと式（11）となる。

式（11）は式（10）を用いて以下のように変形できる。

式（12）の|ω|は高周波数成分を拡大し解が不安定となるため、実際には様々なフィルタ関数のフーリエ変換が用いられている。本発明では、式（14）で表されるShepp-Loganフィルタをフィルタ関数として用いる。従って、式（12）より磁界分布の推定値

を式（13）のように求めることができる。

(1.4 Reconstruction method)
Estimated magnetic field distribution on sample from observed quantity g (X, θ)

The method of reconstructing is shown.
From g (X, θ)

In general, the X-ray CT method widely used can be used for the reconstruction. There are various methods such as an FBP method (Filtered Backprojection), a CBP method (Convolution Backprojection), and an EL-ME method. Here, an application example of the FBP method will be described as an example.
The two-dimensional Fourier transform H (ξ, η) of the magnetic field distribution h (x, y) is expressed as in equation (4).

Here, when expressed in polar coordinates (ω, θ) as ξ = ω cos θ and η = ω sin θ, the following equation is obtained.

Furthermore, when equation (5) is transformed, it becomes as follows.

Expression (10) indicates that the two-dimensional Fourier transform H (ωcosθ, ωsinθ) of the magnetic field distribution is equal to the one-dimensional Fourier transform G (ω, θ) of the observed value. The two-dimensional inverse Fourier transform of H (ξ, η) is expressed by Equation (11) in terms of polar coordinates (ω, θ).

Equation (11) can be modified as follows using Equation (10).

Since | ω | in equation (12) enlarges the high frequency component and the solution becomes unstable, the Fourier transform of various filter functions is actually used. In the present invention, the Shepp-Logan filter represented by Expression (14) is used as a filter function. Therefore, the estimated magnetic field distribution from equation (12)

Can be obtained as shown in Equation (13).

[2. Numerical simulation)
A numerical simulation is performed to confirm the effectiveness of the magnetic field distribution reconstruction method using a GMR head. First, forward analysis is performed in which the GMR head is scanned over the sample to obtain voltage changes due to magnetic field distribution. Next, the results obtained by forward analysis are reconstructed as simulated measurement data.

式（15）は磁界のY方向の積分値をそれぞれ膜厚dの範囲で平均した値を観測値として用いている。 (2.1 forward analysis)
The GMR head is scanned over the sample and forward analysis is performed to observe voltage changes from the magnetic field distribution. The magnetic field distribution is shown in FIG. At the center of the distribution, there are magnetic field distributions of N pole (white) and S pole (black) each having a size of about 90 nm × 20 nm. FIG. 7 shows simulated measurement data obtained by scanning the magnetic field distribution of FIG. 6 from 0 ° to 180 ° at 1 ° intervals. In FIG. 7, the vertical axis represents the scan angle θ, and the horizontal axis represents the scan position X. Further, FIG. 8 shows simulated measurement data obtained by adding a 10% error to the scanned image in FIG.
Here, in calculating the measurement data, equation (15) was used instead of equation (1) in consideration of the film thickness d of the GMR head.

Equation (15) uses the average value of the integral value in the Y direction of the magnetic field in the range of the film thickness d as the observed value.

(2.2 Reconstruction results)
Simulated Measurement Data FIG. 7 and FIG. 8 show the result of reconstructing the magnetic field distribution using equation (13).
FIG. 9 shows the magnetic field distribution reconstructed based on FIG. 7, and FIG. 10 shows the magnetic field distribution reconstructed based on FIG. 8 with 10% error added. It can be seen that the magnetic field distribution can be reconstructed regardless of the presence or absence of errors.
FIG. 11 shows the distribution of the center in the horizontal direction of the correct magnetic field distribution (◯ mark), the reconstructed magnetic field distribution without error (x mark), and the reconstructed magnetic field distribution with 10% error (□ mark). Even when there is an error, there is no significant difference compared to when there is no error.

[3. (Relationship between magnetic field distribution and voltage change)
We consider a mathematical model of equation (1) that shows the relationship between the magnetic field distributed on the bottom surface of the GMR head and the voltage change observed at both ends of the head. As shown in FIG. 12, the magnetic field from the sample forms a magnetization distribution in the head, and a distribution of change in resistivity proportional to the magnetization distribution appears. When a constant current is passed through the head, a voltage change occurs at both ends of the head due to the distribution of resistivity change. These processes are modeled as follows.

ただし、aはGMRヘッドの長手方向の長さで、ｄ、g、μはそれぞれ図１３に示すようにGMRヘッドの膜厚、ヘッドとシールドとのギャップ、ヘッドの透磁率である。
ヘッドの電位分布をφ(Y,Z)とすると、φは式（19）で表される偏微分方程式を満たす。

ただし、κは電気伝導率である。ヘッドの電気伝導率が既知であれば、図１４と以下に示すような境界条件のもとで式（19）を解き、ヘッドの電位分布を求めることができる。ヘッドの両端の電位一定の境界をΓ_１、Γ_２、それ以外の絶縁の境界をΓ_３とした。

ヘッドの抵抗率変化の分布は磁化分布m(Y,Z)に比例するため、抵抗率ρ(Y,Z)は式（23）で表される。

ただし、Δρは抵抗率変化の範囲を示す。従って、電気伝導率κ(Y,Z)は抵抗率の逆数となり、

となる。 Similarly to the above (paragraph 0013), the z component of the magnetic field distribution at the lower end surface of the head is assumed to be h (x, y). Assuming that the head thickness is sufficiently thin and the magnetization distribution in the thickness direction is uniform, and the Z component of the head magnetization distribution is m (Y, Z), the magnetization distribution m (Y, Z) It is proportional and can be expressed by series expansion as in the following equation (16).

Where a is the length of the GMR head in the longitudinal direction, and d, g, and μ are the thickness of the GMR head, the gap between the head and the shield, and the magnetic permeability of the head, as shown in FIG.
When the potential distribution of the head is φ (Y, Z), φ satisfies the partial differential equation expressed by the equation (19).

However, (kappa) is electrical conductivity. If the electrical conductivity of the head is known, Equation (19) can be solved under the boundary conditions as shown in FIG. 14 and the following to obtain the potential distribution of the head. The constant potential boundaries at both ends of the head were Γ ₁ and Γ ₂ , and the other insulating boundaries were Γ ₃ .

Since the distribution of the change in resistivity of the head is proportional to the magnetization distribution m (Y, Z), the resistivity ρ (Y, Z) is expressed by Expression (23).

However, (DELTA) (rho) shows the range of a resistivity change. Therefore, the electrical conductivity κ (Y, Z) is the reciprocal of the resistivity,

It becomes.

The magnetization distribution calculated assuming the A _n of formula (16), equation (19), equation (23), when the electrostatic field analysis using Equation (24), the potential distribution of the head relative to the assumed magnetic field A current density distribution is obtained. The resistance of the entire head is obtained from the potential distribution and the current density distribution, and the relationship between the resistance and the coefficient A ₀ is shown in FIG. However, with respect to A _n which formula (16) is sufficiently converged (n = 0 to 5), giving a uniform random number between -0.1～0.1 sample points was 200 points.
Resistance of the entire head, regardless of the various A _n which is generated by the random number (n = 1~5), that is proportional only to A ₀ is seen from FIG. 15. Here, A ₀ is an average value of the magnetic field distribution h (x, y) at the lower end of the GMR head from the equation (17). Therefore, the voltage change observed at both ends of the GMR head can be modeled as an integral value of the magnetic field distribution at the lower end of the head as shown in Equation (1).

  FIG. 16 is a diagram showing another configuration example of the magnetic field distribution measuring apparatus according to the present invention, and corresponds to the invention according to claim 2. That is, instead of one-dimensional translation scanning of the thin film magnetic sensor, the sensors are stacked in multiple layers. A rotation mechanism including a turntable and a motor for rotating the measurement target object in a horizontal plane, an angle sensor for detecting a rotation angle of the measurement target object, a voltage signal (ΔV) from the probe, and the position of the probe Since it has the same magnetic field distribution reconstructing means for reconstructing the magnetic field distribution based on the information (X) and the rotation angle signal (θ) output from the angle sensor, it is the same as FIG. Is omitted.

  FIG. 17 is a diagram showing still another configuration example of the magnetic field distribution measuring apparatus according to the present invention, and corresponds to the invention according to claim 3. In other words, instead of rotating the sample, a plurality of thin film magnetic sensors (probes) arranged at predetermined angles and intervals are arranged on a straight line, and the magnetic field distribution is measured while the sample is sequentially sent by an actuator or the like. It is. 1 is the same as FIG. 1 in that it comprises magnetic field distribution reconstruction means for reconstructing the magnetic field distribution from the position information of each probe, the angle information, the position signal of the sample, and the output signal from each probe. Since it is, the illustration is omitted.

  Needless to say, the magnetic field distribution measuring apparatus according to the present invention can be used as a high-resolution magnetic reading apparatus for an information medium recorded magnetically.

It is a figure which shows the structural example of the magnetic field distribution measuring apparatus which concerns on this invention. It is the schematic which expanded the HDD head. It is a figure which shows the structure of a GMR head. It is a figure for demonstrating the method of scanning the sample which has a magnetization distribution using a GMR head, and measuring a magnetic field distribution. It is a figure which shows a mode that FIG. 4 was seen from the top. It is a figure which shows the magnetic field distribution of a sample. FIG. 7 is a diagram showing simulated measurement data when the magnetic field distribution of FIG. 6 is scanned from 0 to 180 degrees at intervals of 1 degree. The vertical axis represents the scan angle θ, and the horizontal axis represents the scan position X. It is a figure which shows the simulation measurement data at the time of adding 10% of error to the scan image of FIG. It is a figure which shows the magnetic field distribution reconfigure | reconstructed based on the data of FIG. It is a figure which shows the magnetic field distribution reconfigure | reconstructed based on the data of FIG. Correct magnetic field distribution (Fig. 6, circle), reconstructed magnetic field distribution without error (Fig. 9, x), reconstructed magnetic field distribution with 10% error (Fig. 10, □) It is a figure which shows distribution. It is a figure which shows the relationship between the magnetic field distributed on the lower end surface of a GMR head, and the voltage change observed at the both ends of a head. It is a figure which shows the cross section of a GMR head and a shield. It is a figure which shows the model for electric field calculation. Is a diagram showing the relationship between the resistance change and the coefficient A _0. It is a figure which shows the other structural example of the magnetic field distribution measuring apparatus which concerns on this invention. It is a figure which shows the further another structural example of the magnetic field distribution measuring apparatus which concerns on this invention.

Claims (7)

A magnetic field distribution measuring device that measures the distribution of a magnetic field leaking into a space from an object to be measured, the device comprising:
A probe comprising a thin film magnetic sensor for detecting a magnetic field distribution in the vicinity of the object to be measured as a voltage or current output signal;
An actuator that causes the probe to scan one-dimensionally in the film thickness direction of the thin film magnetic sensor;
A rotation mechanism for rotating the object to be measured in a horizontal plane;
An angle sensor for detecting a rotation angle of the measurement object;
Magnetic field distribution reconstruction means for reconstructing the magnetic field distribution based on an output signal from the probe, a position signal of the probe output from the actuator, and a rotation angle signal output from the angle sensor. Magnetic field distribution measuring device characterized by. A magnetic field distribution measuring device that measures the distribution of a magnetic field leaking into a space from an object to be measured, the device comprising:
Two or more thin film magnetic sensors for detecting a magnetic field distribution in the vicinity of the object to be measured as an output signal of voltage or current, and a multilayered probe,
A rotation mechanism for rotating the object to be measured in a horizontal plane;
An angle sensor for detecting a rotation angle of the measurement object;
Magnetic field distribution reconstructing means for reconstructing the magnetic field distribution based on an output signal from each probe, a position signal of each probe, and a rotation angle signal output from the angle sensor; Magnetic field distribution measuring device. A magnetic field distribution measuring device that measures the distribution of a magnetic field leaking into a space from an object to be measured, the device comprising:
An actuator that translates the object to be measured one-dimensionally in a predetermined direction in a horizontal plane;
A group of probes in which a plurality of thin film magnetic sensors for detecting magnetic field distribution in the vicinity of the object to be measured as voltage or current output signals are arranged in the predetermined direction in the horizontal plane at predetermined intervals and at mutually different angles. When,
Magnetic field distribution for reconstructing the magnetic field distribution based on the output signal from each probe of the probe group, the position information of each probe, the tilt angle of each probe, and the position signal of the measurement object output from the actuator A magnetic field distribution measuring apparatus comprising a reconfiguring means.   The magnetic field distribution measuring apparatus according to claim 1, wherein the actuator is configured by a piezo element.   The magnetic field distribution measuring apparatus according to claim 1, wherein the algorithm for reconstructing the magnetic field distribution is a CT algorithm.   6. The magnetic field distribution measuring apparatus according to claim 1, wherein the thin film magnetic sensor is a GMR head.   The magnetic field distribution measuring apparatus according to claim 1, further comprising a display unit that displays the reconstructed magnetic field distribution.

Images