JPH08273231A - Magnetic field detecting medium and magnetic head position adjusting method using the medium - Google Patents

Abstract

PURPOSE: To easily and surely adjust the position of a magnetic head to a light spot by possessing a magnetic layer having vertical magnetic anisotropy for detecting the change of an outer magnetic field in size by the change in its magneto-optical effect. CONSTITUTION: A head element 22 is moved in the radial direction of the medium disk by a head moving means 17 in looking at the RF output of an RF level meter 15 of find the position of the head element 22, where the amplitude of the RF output becomes the max. Subsequently, the head element 22 is moved on a straight line in the tangential direction of the disk passing through a position where the amplitude in the disk radial direction becomes the max., so as to find the position of the head element 22, where the amplitude of the RF output becomes the max. in a similar manner. At this time, when the first output amplitude in the disk radial direction is below the max. value, the position where the output amplitude in the disk radial direction becomes the max. should be found over again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field detecting medium used for determining an optimum position of a magnetic head with respect to a light spot in a magneto-optical disk device, and a magnetic head position adjusting method using the medium. .

[0002]

2. Description of the Related Art In a conventional magneto-optical disk which is a magneto-optical recording medium, when new data is recorded, it is necessary to go through three processes of erasing old data, recording and verifying. Therefore, the magneto-optical disk must be rotated at least three times when recording data, and it is difficult to increase the transfer rate during recording.

As one of the methods for improving this problem,
A system using so-called magnetic field modulation overwrite technology is currently in the stage of practical application. This technique does not require an erasing process at the time of recording and is a technique capable of increasing the transfer rate by about 1.5 times as compared with the conventional magneto-optical disk. In this case, it is indispensable to modulate the recording magnetic field at a high speed, but in a fixed magnetic head in which the distance between the recording medium and the magnetic head is large, it is necessary to simultaneously satisfy the sufficient recording magnetic field and the high speed modulation. It is also very difficult from the perspective of.

Therefore, it becomes necessary to use a so-called floating magnetic head that is generally used in hard disks. In order to avoid wear and damage due to contact with the surface of the recording medium, this flying type magnetic head causes a head element to be spaced a minute distance from the surface of the recording medium (so-called flying height) by an air flow generated on the surface of the recording medium when the recording medium rotates at high speed. Is a magnetic head configured to generate a magnetic field while levitating and traveling, and has a structure in which a coil is wound by providing an extremely small head element on a part of a wing-shaped member called a slider. ing.

By the way, in magneto-optical recording, recording is performed by applying a recording magnetic field from a magnetic head to a portion heated to a high temperature by irradiating the magneto-optical disk with laser light. The position and the magnetic field generation area must match. However, since the flying height of the floating magnetic head is on the order of microns, the magnetic field generation area is very narrow, and it is difficult to perform alignment with only mechanical accuracy.

For this reason, mainly in the present situation, the floating magnetic head is moved little by little with respect to the magneto-optical disk for recording, and the signal is read to obtain the signal amplitude and signal quality (for example, C / N, etc.). The position of the head element of the floating magnetic head with respect to the light spot is adjusted by sequentially performing the confirmation of (1).

[0007]

However, the above-mentioned position adjusting method is very complicated and takes a lot of time and labor, which is a big problem in production. Of course, a method of visually adjusting the position of the head element is often used, but this method has a problem in that it is extremely inferior in terms of accuracy.

The present invention has been proposed in view of the above-mentioned problems, and the position adjustment of the magnetic head with respect to the light spot is performed even for a magnetic head having a very narrow magnetic field generation region such as a head element of a floating magnetic head. An object of the present invention is to provide a novel magnetic field detection medium that can be very easily and reliably performed, and further to provide a magnetic head position adjusting method capable of significantly improving the yield and reliability of products. The purpose is to provide.

[0009]

The object of the present invention is a magnetic field detecting medium and its method used when adjusting the position of a magnetic head with respect to a light spot in a magneto-optical recording / reproducing apparatus.

The magnetic field detecting medium of the present invention comprises at least one magnetic layer having perpendicular magnetic anisotropy, and the magnetic layer has an external magnetic field at a magnetic field detection temperature of room temperature or higher and lower than the Curie temperature. It is characterized by the fact that the magnetization direction can be changed according to the above, and a detectable magneto-optical effect is exhibited, and a change in the magnitude of the external magnetic field applied to the magnetic layer is detected by this change in the magneto-optical effect.

The characteristics required for the magnetic field detecting medium of the present invention are such that (a) the direction of magnetization changes (inverts) according to an external magnetic field (recording magnetic field), and (b) signal detection is possible. Regarding the material that has the magneto-optical effect, for example, the material satisfying the characteristic (b), some materials have been proposed in the process of research and development of the magneto-optical recording medium.

However, these studies have been conducted mainly for use as a recording medium, and it is important to ensure the stability of recorded magnetic domains, and it is required that the coercive force near room temperature be as large as possible. It Therefore, no attention has been paid to a medium in which the coercive force near room temperature is almost zero, or the magnetization is in the in-plane direction.

On the other hand, as a transfer medium for a reading method called magnetic transfer reading, a material having a large magneto-optical effect and a small coercive force has been studied. It is required that a magnetic domain having a magnetic domain diameter of about 1 μm can be accurately transferred by a leakage magnetic field, and that there is no magnetic domain that does not correspond to the recording magnetic domain in the field of read light. It must be good and have a small domain wall coercive force.

On the other hand, in the magnetic field detecting medium of the present invention, the squareness ratio is smaller than 1 and the saturation magnetic field is small,
Further, a material having a relatively high Curie temperature can be used, and it is essential to use materials and compositions which have not been noticed so far.

Therefore, the magnetic field detecting medium of the present invention is
Even if the elements constituting the magnetic layer are the same as those of the conventional magneto-optical recording medium or transfer medium, their magnetic characteristics and composition are determined from a completely different viewpoint. It's completely different.

As described above, according to the present invention, by using the magnetic thin film of the material and the composition which have not been noticed so far, the squareness ratio is smaller than 1, the saturation magnetic field is small, and the Curie temperature is relatively high, The present invention provides a magnetic field detection medium that satisfies the two conditions.

In the magnetic field detecting medium of the present invention, the magnetization direction in the magnetic layer is 200 at the magnetic field detecting temperature.
It is desirable that the magnetic field can change according to an external magnetic field of Oersted or lower.

Further, as described above, the value of the saturation magnetization is larger than the value of the residual magnetization (the squareness ratio is smaller than 1), and the value of the saturation magnetic field of the magnetic layer near the magnetic field detection temperature. Is preferably greater than or equal to the maximum value of the external magnetic field (recording magnetic field).

As the magnetic field detecting medium, a disk-shaped medium mainly composed of a transparent disk-shaped substrate on which a magnetic layer having the above-mentioned properties is formed is assumed. It has one or more magnetic films having a directionality, and has a characteristic that the recording magnetic field becomes larger than the coercive force at the above-mentioned detection temperature. In a normal magneto-optical disk, where the recording magnetic field does not exceed the coercive force unless the temperature rises to near the Curie temperature, the Kerr rotation angle is almost zero at such high temperatures, and the amplitude of the reproduced signal cannot be detected. In addition, it cannot be used in the present invention.

The position adjustment is mainly performed in a state where the magneto-optical recording / reproducing apparatus is provided with an optical pickup and a magnetic head,
That is, it is assumed that the mechanical deck is assembled, and the maximum magnetic field generation position of the magnetic head with respect to the light spot is found by detecting the reproduction signal which changes on the magnetic field detection medium.

Here, it is necessary that the value of the saturation magnetization of the magnetic layer in the magnetic field detecting medium is larger than the value of the residual magnetization, that is, the so-called squareness ratio (residual magnetization / saturation magnetization) is smaller than 1. Is. This is because when the value of the saturation magnetization is substantially equal to the value of the residual magnetization, it may happen that the magnetization direction does not change at the maximum magnetic field generation position of the magnetic head. Because it will be difficult to find.

A specific method of detecting the maximum magnetic field generation position is, for example, a method of detecting the maximum magnetic field generation position by examining the change in the amplitude of the reproduction signal. That is, first, for example, the magnetic head is moved back and forth to detect the position where the amplitude of the reproduction signal is maximum. Then, the magnetic head is moved to the left and right, and the position where the amplitude of the reproduction signal is maximum is similarly detected. At this time, if the amplitude of the reproduced signal in the front-rear direction is less than or equal to a threshold value, the maximum amplitude error in the front-rear direction may be large. Search for the position. By performing the above work, the position of the magnetic head is set to a position where the maximum magnetic field is generated with respect to the light spot.

As a method of detecting the maximum magnetic field generation position of the magnetic head, the maximum magnetic field generation is performed by detecting the error number or C / N of the reproduction signal instead of measuring the amplitude of the reproduction signal as described above. You may find out a position.

Further, the present invention is suitable for position adjustment of a magnetic head such as a head element of a flying type magnetic head, in which a magnetic field generating region is extremely narrow.

Further, as a magnetic layer which can realize a changeable magnetization direction according to an external magnetic field and a detectable Kerr rotation angle at a detection temperature higher than room temperature and sufficiently lower than the Curie temperature. , At least one layer of a rare earth-transition metal amorphous thin film is conceivable.

In this case, the magnetic layer has a composition (so-called TM rich) or a composition in which the compensation temperature is lower than room temperature and the sublattice magnetization of the transition metal is larger than the sublattice magnetization of the rare earth element near the magnetic field detection temperature. It is desirable to configure the magnetic field detection temperature region as having a composition (so-called RE rich) in which the sublattice magnetization of the rare earth element is larger than the sublattice magnetization of the transition metal (so-called RE-rich), and which has no compensation temperature according to the purpose. The above conditions can be satisfied by changing the composition of the material and the preparation conditions.

Specifically, it is conceivable to use a magnetic layer containing at least Gd as a rare earth element, and it is possible to use a magnetic layer containing at least Fe and Co as transition metal elements.

Here, in order to improve the corrosion resistance and the reliability against repeated recording, additional elements such as Cr, Ti and B may be added.

[0029]

The magnetic field detecting medium according to the present invention has at least one magnetic layer having perpendicular magnetic anisotropy, and the magnetic layer is exposed to an external magnetic field at a magnetic field detecting temperature of room temperature or higher and lower than the Curie temperature. The magnetization direction can be changed accordingly, and a detectable magneto-optical effect is shown.

Therefore, at the magnetic field detection temperature,
For example, when a magnetic head that generates a recording magnetic field is brought close to this magnetic field detection medium, the magnitude of the magneto-optical effect changes depending on the magnitude of the magnetic field applied to the magnetic layer.

Therefore, if the change in the magneto-optical effect is taken out as a reproduction signal, the change in the magnitude of the external magnetic field applied to the magnetic layer is detected.

The magnetic head position adjusting method according to the present invention utilizes such a phenomenon, and the maximum magnetic field generation position of the magnetic head with respect to the light spot is determined by the magnetic head on the adjusting magnetic field detecting medium. Since it is equivalent to the maximum amplitude position of the reproduced signal when it is moved back and forth and left and right, accurate maximum magnetic field is generated by adjusting the position while observing the change of amplitude waveform while moving the magnetic head in each direction. The position can be easily found.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of specific embodiments in which the magnetic field detecting medium of the present invention and the magnetic head position adjusting method using the same are applied to a magneto-optical disk device having a so-called floating magnetic head, with reference to the drawings. While explaining in detail.

Structure of flying type magnetic head and medium for magnetic field detection
In order to avoid abrasion damage due to contact with the surface of the magneto-optical disk, the flying-type magnetic head moves the head element from the magneto-optical disk surface at a minute distance (so-called) from the magneto-optical disk surface by the air flow generated on the surface of the magneto-optical disk when the recording medium rotates at high speed. This is a magnetic head having a flying height (here, of the order of microns) and configured to generate a magnetic field while flying, and an extremely small head element is provided in a part of a wing-shaped member called a slider to form a coil. It has a wound structure.

The magnetic head whose position is to be detected in the present invention is not limited to the floating magnetic head described above, but a type in which the head slides on the medium or a floating magnetic head used in a magnetic disk is used. Head, its shape and contact,
It may be of any type as long as it is necessary to make the magnetic field generation region of the magnetic head coincide with the spot position of the laser beam regardless of non-contact.

In the target magneto-optical recording / reproducing apparatus, the magnetic field obtained on the medium is restricted by the size of the magnetic head, the power consumption, the distance between the medium and the magnetic head, the width of the magnetic field generation region, and the like. The size is generally smaller than 1 kOe, and in most cases is about 100 to 600 Oe.

On the other hand, as shown in FIG. 1, a disk-shaped medium as a magnetic field detecting medium used for adjusting the position of the magnetic head is formed on a transparent disc-shaped substrate 1 made of polycarbonate, glass or the like, as shown in FIG. A dielectric layer 2 made of Si ₃ N ₄ or the like is formed, and a magnetic layer 3 is formed on the dielectric layer 2.
However, a metal reflective layer 5 made of Al or the like is further formed on the magnetic layer 3 with the dielectric layer 4 interposed therebetween, and a protective film 6 made of an ultraviolet curable resin or the like is formed on the uppermost layer (the lowermost layer when used). It is composed of a film.

Here, since the rise of the medium temperature deteriorates or changes the magnetic field detection characteristics, in order to avoid this, the metal reflection layer 5 made of Al or the like is used more than that used in a usual magneto-optical recording medium. Thicker (eg 200n
m) so that the heat of the medium is effectively released. The thickness of the metal reflection layer 5 should be determined depending on the linear velocity (relative velocity between the laser irradiation position and the medium) to be used and the film of other layers (the magnetic layer 3 and the dielectric layers 2 and 4). Since the thickness depends on the thickness and the like, the optimum range may be set according to these factors. However, when the magnetic layer 3 is thin, the metal reflection layer 5 must also function as a reflection film. The above is preferable. If this film thickness is too thin, the laser beam will be transmitted and a sufficient amount of return light cannot be obtained.

By making the structure of the magnetic field detecting medium the same as that of the magnetic recording medium actually used as described above and adjusting the measuring conditions to the operating conditions (rotational speed of the disk, etc.), a very practical recording magnetic field can be obtained. It becomes possible to perform detection.

However, if the position of the magnetic head is merely adjusted, the shape of the magnetic field detecting medium does not necessarily have to be a disk shape, and in principle, the size is large enough to cover the laser irradiation area. It only needs to exist, and its shape is also arbitrary.

Further, as in the present example, the structure in which the laser is irradiated through the transparent substrate is less likely to be unable to detect a signal due to the influence of dust adhering to the surface of the medium, but with such a structure. It is not absolutely necessary that the substrate be made of, for example, a non-magnetic material such as Al (in the case of a system in which a magnetic head and an optical head are opposed to each other, the thickness of this substrate is A magnetic layer is formed on the obtained magnetic head and the medium (determined from the distance between the medium) (may be sandwiched by a dielectric film to prevent corrosion). You may make it irradiate.

Further, the material of the transparent substrate is not limited to polycarbonate, but a resin such as acrylic resin or polyolefin,
Any known material such as glass can be used.

Information for tracking servo or the like may be recorded in advance on the substrate by the unevenness of the substrate, or of course, a flat substrate may be used.

In forming each of the above layers, for example, first, the substrate 1 is formed by a reactive RF sputtering method using a mixed gas of Ar / N ₂ and a Si target.
The dielectric layer 2 is made of Si ₃ N ₄ and has a film thickness of about ₃₀ n.
The film is formed on m. Next, after forming the magnetic layer 3 with a film thickness of about 100 nm by the DC magnetron sputtering method, the dielectric layer 3 is formed with a film thickness of about 30 nm like the dielectric layer 2. Then, after forming the metal reflective layer 5 made of Al, the protective film 6 is formed by spin coating.

The target-substrate distance at the time of sputtering was 150 mm, the substrate temperature was not particularly controlled, and the maximum temperature was about 60 ° C. when examined by a thermolabel. The input power is 2 kW when the dielectric film is formed, and the rare earth target is 3 kW when the magnetic film is formed.
The target of the transition metal was 00 W, and was about 1 kW.

As is well known, various magnetic characteristics such as coercive force Hc and perpendicular magnetic anisotropy are determined by the sputtering gas pressure, the power applied to the target, the target-substrate distance, the substrate material and surface properties, and the substrate temperature. It is affected by many factors such as, and does not correspond one-to-one with the stoichiometric composition.

The magnetic layer 3 is, for example, Gd-Fe-Co.
It is a thin film made of a Cr-based rare earth-transition metal amorphous material, and the magnetic layer 3 has perpendicular magnetic anisotropy. This disc-shaped medium exhibits a detectable Kerr rotation angle in addition to a changeable magnetization direction in accordance with an external magnetic field of 200 Oersted or less at a detection temperature of a predetermined temperature or higher sufficiently higher than room temperature and sufficiently lower than the Curie temperature, and The value of the saturation magnetization Ms of the magnetic layer 3 is larger than the value of the residual magnetization Mr, that is, the value of the so-called squareness ratio (Mr / Ms) is smaller than 1, and near the magnetic field detection temperature,
It has a characteristic that the value of the saturation magnetic field Hs of the magnetic layer 3 is equal to or _larger than the maximum value of the recording magnetic field H _REC that can be generated.

Here, as an example, Gd _x (Fe _0.89 C
o _0.07 Cr _0.04) in the magnetic layer 3 having a composition of _1-x, the coercive force when changing the values of x Hc and saturation magnetization M
The results of examining the change of s are shown in FIG. As described above, in the Gd-Fe-Co (-Cr) -based rare earth-transition metal amorphous material, the magnetic characteristics such as the coercive force Hc and the saturation magnetization Ms can be significantly changed by changing the composition.

As can be seen from FIG. 2, this material has a very narrow composition range in which the squareness ratio (the ratio of the residual magnetization and the saturation magnetization) is 1, and even when the squareness ratio is 1, the coercive force is large. Is about several kOe, and the Curie temperature is high. Therefore, it is not very excellent as a recording medium from the viewpoint of recording characteristics and recording magnetic domain stability. For this reason, many researchers have studied increasing the coercive force, and methods such as adding Tb and forming a double-layer exchange-coupling film with TbFeCo, DyFeCo, or the like having a large coercive force have been investigated. There is.

Although the study of using a material having a high Curie temperature and a small coercive force alone as described above was conducted in the early days when the magneto-optical recording was devised, after that, the Curie temperature was not high and the coercive force was high. Most of the studies have been conducted to obtain a large one and a large magneto-optical effect.

However, in GdFeCo, which has many drawbacks as a magneto-optical recording medium and cannot be used alone, the characteristics which are disadvantageous as a recording medium are all excellent characteristics when used in the present invention, and the magnetic field of the present invention is used. It is one of the most suitable detection media.

In this embodiment, the specific composition of the magnetic layer is Gd _0.18 (Fe _0.95 Co _0.05 ) _0.82 and the Curie temperature is about 250 ° C. Moreover, the material of the magnetic layer shown here is an example, and a generally known rare earth transition metal-based material, PtCo-based material, or the like can be used. Further, Ti, B or the like may be used as an additive element for these materials.

In a normal magneto-optical disk, as shown by the curve A in FIG. 3, the coercive force Hc of this magneto-optical disk is much larger than the recording magnetic field H _REC near the room temperature Tr, and this coercive force Hc is large. Is below the recording magnetic field H _REC only in the vicinity of the Curie temperature Tc. On the other hand, as shown in FIG. 4, the Kerr rotation angle near the Curie temperature Tc is almost zero, and it is impossible to detect the change in the magnetization direction of the magneto-optical disk.

Therefore, the magnetic field detecting medium for position adjustment used in this embodiment has a room temperature Tr or a predetermined temperature higher than the room temperature Tr and sufficiently lower than the Curie temperature Tc as shown by a curve C or a curve B in FIG. At T _th , the coercive force has a value smaller than that of the recording magnetic field H _REC , and a sufficient Kerr rotation angle can be obtained in this temperature region, so that the recording magnetic field can be detected.

Position Adjustment of Flying Magnetic Head The position of the floating magnetic head is adjusted using the above-described magneto-optical disk for position adjustment. In this embodiment, as shown in FIG. 5, a magneto-optical disk is used. The position of the flying magnetic head is adjusted in a state where the mechanical deck 11 of the apparatus is assembled. A board 13 (main board and mechanical control board), a magnet head drive board 14 (hereinafter simply referred to as a magdra board 14) are provided on the mechanical deck 11 to which the flying magnetic head 12 is fixed at one end of its head arm 21. And the flying magnetic head 12 is provided with head moving means 17 for moving the flying magnetic head 12 back and forth and left and right (that is, the disk radial direction and the disk tangential direction of the magneto-optical disk).

Further, a high frequency (RF) level meter 15 is connected to the substrate 13 and an EF is attached to the magdra substrate 14.
The M generation means 16 is connected. Instead of the EFM generating means 16, a direct current generating means, a single frequency generating means or the like may be used.

Then, in order to adjust the position of the light spot of the floating magnetic head 12 (which is due to the optical pickup provided on the lower portion of the substrate 13 and is not shown), first, the above-mentioned adjustment is performed. Insert the disc cartridge 18 provided with the magneto-optical disc of FIG.
An EFM random pattern or a fixed pattern is input from the FM generating means 16 to the magdora substrate 14. Then, an AC magnetic field is generated from the head element 22 provided at the tip of the head arm 21 of the floating magnetic head 12.

In this state, the RF level meter 15
While observing the RF output, the head moving means 17 moves the head element 22 in the disk radial direction to find the position of the head element 22 where the amplitude of the RF output is maximum. Subsequently, the head element 22 is moved along a straight line in the tangential direction of the disk passing through the position where the amplitude in the disk radial direction is maximum, and the position of the head element 22 where the amplitude of the RF output is maximum is similarly found. At this time, if the maximum value of the initial output amplitude in the disk radial direction is less than a certain value, there is a possibility that the position error of the head element 22 at which the output amplitude in the disk radial direction becomes maximum is large. , Again, find a position where the output amplitude in the radial direction of the disk becomes maximum. By the above work, the position adjustment of the head element 22 of the floating magnetic head 12 with respect to the light spot is completed.

The above working steps are shown in FIG. As shown in this flowchart, the position can be adjusted by performing scanning at most three times in the disk radial direction or the disk tangential direction.

By the way, in the above position adjustment, there may be a case where the RF output amplitude becomes broad in the vicinity of the position where the RF output amplitude is maximum and the change in the amplitude is poor and the position adjustment becomes difficult. R
When the position where the F output amplitude is maximized was examined for the amplitude change in each of the disk radial direction and the disk tangential direction, the result shown in FIG. 7 was obtained. As shown in this characteristic diagram, the changes are shown almost completely symmetrically with respect to the maximum amplitude position in both the disk radial direction and the disk tangential direction. Therefore, it is understood that there is almost no problem even if an appropriate amplitude value is selected and the center positions of the two points having the value are regarded as the maximum amplitude position.

As described above, in the magnetic head position adjusting method of the present embodiment, the maximum magnetic field generation position of the magnetic head with respect to the light spot is determined by moving the floating magnetic head 12 forward and backward and left and right on the adjusting magneto-optical disk. Since it is equivalent to the maximum amplitude position of the RF output which is the reproduction signal when moved in the (disc radial direction and disc tangential direction),
By adjusting the position while observing changes in the amplitude waveform while moving the levitation type magnetic head 12 in each direction, it is possible to easily find an accurate maximum magnetic field generation position visually.

Therefore, the position of the magnetic head can be adjusted easily and with high accuracy, and the yield and reliability of the products can be greatly improved. Also, for example,
By making the magnetic field sensitivity characteristic of the RF output amplitude of the adjusting magneto-optical disk equal to that of the ordinary magneto-optical disk for recording / reproducing, the positional deviation between the optical spot and the magnetic head due to the change in the disk thickness or the tracking trace. It is possible to grasp the decrease state of the RF output amplitude due to.
This makes it possible to perform various evaluations such as the minimum magnetic field current and the core shape.

As a method of detecting the maximum magnetization generation position of the magnetic head, the recording magnetic field H shown in this embodiment is used.
_In addition to the method of evaluating the signal amplitude of the reproduced signal obtained with the change in the magnetization due to _REC, the method of inputting the reproduced signal into the spectrum analyzer to evaluate the C / N, or any modulation method is used. There is a method of evaluating an error based on a reproduction signal obtained with the magnetization by the recording magnetic field H _REC .

For example, a method of evaluating an error based on the reproduced signal will be described. First, the relationship between the recording magnetic field H _REC and the number of errors is examined. As the measurement conditions, the relationship between the signal and the error number obtained with the change in the magnetization due to the recording magnetic field H _REC was measured with a linear velocity of the magneto-optical disk of 1.4 m / s and a laser power of 4.8 mW. The results are as shown. As shown in this characteristic diagram, the number of errors decreases almost monotonously as the recording magnetic field H _REC increases, and the relationship is almost linear. Therefore, it is sufficiently possible to monitor the recording magnetic field H _REC based on this relationship, and the position of the magnetic head can be adjusted using this magneto-optical disk.

[0065] As the positioning method of the magnetic head, while generating arbitrary recording magnetic field H _REC moving the magnetic head over the optical disk, most of the value of the number of errors shown in FIG. 8 for the recording magnetic field H _REC The position of the magnetic head may be adjusted so that the values are close to each other.

Squareness Ratio of Magnetic Layer and Magnetic Field Detection Characteristics By the way, in the magneto-optical disk which is the medium for magnetic field detection, as a material of the magnetic layer 3, Gd-Fe-Co is used.
When a Cr-based rare earth-transition metal amorphous material is used, the amorphous material has a compensation temperature of room temperature or lower, and is Fe or Co which is a transition metal as compared with the sublattice magnetization of the rare earth element near the magnetic field detection temperature. There is a composition having a large sublattice magnetization (so-called TM rich) and a composition having a smaller sublattice magnetization of a transition metal (so-called RE-rich) than the sublattice magnetization of Gd which is a rare earth element.

In order to detect the magnetic field generated by the magnetic head, it is essential that the magnetization in the magnetic layer of the magnetic field detection medium be reversed, so the coercive force Hc in the magnetic layer is smaller than the magnetic field generated by the magnetic head. There must be. The rare earth-transition metal amorphous material that satisfies this condition can be roughly classified into two types according to its squareness ratio. That is, as shown in FIG.
In the case of the M-rich type and the squareness ratio is less than 1, FIG.
As shown in FIG. 11, when the TM-rich type has a squareness ratio of 1, as shown in FIG. 11, the RE-rich type has a squareness ratio of 1
12 is a case of RE-rich and a squareness ratio smaller than 1 as shown in FIG. Hereinafter, a comparison between the squareness ratio of 1 and a squareness ratio smaller than 1 and a comparison of the TM rich and the RE rich will be described.

(1) Comparison of squareness ratio 1) When the squareness ratio is 1 The above magnetic field detection temperature (in consideration of temperature rise due to laser irradiation)
When the squareness ratio is 1, the Kerr rotation angle θ corresponds to whether the external magnetic field H _ext exceeds or does not exceed the coercive force Hc of the magneto-optical disk as in H _ext2 and H _ext1 as shown in FIG.
The pp value of k can take only a maximum value or a binary value of zero, such as θkp-p1 or θkp-p2. Therefore, for example, when the position of a magnetic head having a magnetic field distribution as shown in FIG. 14 is adjusted, a signal output as shown in FIG. 15 is obtained as the magnetic head moves. When such a magnetic field detection medium is used, it can be confirmed that a magnetic field above a certain specified value is output, but if the magnetic head is within the range where H _ext > Hc, the same signal strength is obtained. Therefore, it is not suitable for determining the optimum position.

Furthermore, the Gd-Fe-C shown in FIG.
In the rare earth-transition metal amorphous material of o (-Cr) system, the coercive force changes abruptly with respect to the composition of Gd, so that the same coercive force can be obtained in a wide area, and a large number of magnetic field detection devices can be used. It is also difficult to reduce variations when the medium is manufactured, and there are many practical problems.

2) When the squareness ratio is less than 1, the magnetic field detection temperature (considering the temperature rise due to laser irradiation)
When the squareness ratio is less than 1 in the external magnetic field H _ext and almost the Kerr rotation angle θk equal to or less than the saturation magnetic field Hs of the external magnetic field H _ext maximum magnetic field detection medium as shown in FIG. 16 Since it can be considered that there is a proportional relationship, it is expected that a signal output proportional to the external magnetic field H _ext will be obtained in this range.

When the relationship between the drive current of the magnetic head and the RF output amplitude (signal strength) was actually examined using the magnetic field detecting medium having the magnetic characteristics shown in FIG. 9, the results shown in FIG. 17 were obtained. Was obtained. Thus, extremely good linearity is shown between the drive current of the magnetic head and the RF output amplitude, and the result of magnetic field detection at this time is equivalent to the case shown in FIG. It can be seen that various magnetic fields can be detected.

On the other hand, as shown in FIG. 18, even when the magnetic field detecting medium exhibiting good magnetic characteristics as described above is used,
Within the range of H _ext > Hs, even if the magnetic field increases, the signal output remains saturated and does not change.
It becomes impossible to accurately obtain the position where _REC becomes maximum. The result of magnetic field detection at this time is shown in FIG.
As shown in FIG. 9, the signal output is saturated in the vicinity of the position where the external magnetic field H _ext is maximum, so that the accurate position adjustment cannot be performed.

Further, as shown in FIG. 16, even if the saturation magnetic field changes from Hs to Hs 'due to the change in composition, the pp value of the Kerr rotation angle θk changes from θkp-p to θkp-p'. Since the linearity and the like with respect to the external magnetic field H _ext are still maintained by itself, there is no great influence such as the case where the squareness ratio is 1 that no RF output is obtained at all.

(2) TM Rich and RE Rich As described above, compositions having a squareness ratio of less than 1 exist in both TM rich and RE rich composition ranges. Less than,
The influence of such a difference in composition on the magnetic field detection characteristics will be described.

In the present embodiment, when the position of the magnetic head is adjusted, the read signal intensity depends on the magnitude of the Kerr rotation angle θk. The value of θk depends on the sublattice magnetization of the transition metal, and the transition. The larger the value of the sublattice magnetization of the metal, the larger the Kerr rotation angle θk. Further, the value of θk is larger when the Curie temperature Tc is higher than the magnetic field detection temperature. Thus, from the viewpoint of the Kerr rotation angle θk, it can be said that it is more advantageous to use the TM rich composition.

On the other hand, not only the position adjustment of the magnetic head,
When considering also the evaluation of the absolute value of the recording magnetic field H _REC , the environmental temperature at the time of measurement, the power of the laser to be irradiated,
Furthermore, it is not preferable that the signal strength changes due to the temperature change of the magnetic field detection medium due to the difference in relative speed between the magnetic field detection medium and the magnetic head or the optical head. In addition to the high Curie temperature Tc, it is necessary that the temperature dependence of the saturation magnetic field Hs be as small as possible.

20 and 21 show the temperature dependence of the TM rich and RE rich Kerr hysteresis loops, respectively. Thus, although depending on the temperature range, the value of the saturation magnetic field Hs tends to increase as the temperature rises in the case of TM rich, but tends to decrease in the case of RE rich. 22 and 23 show the influence of the magnetic field detection characteristics due to such a difference in characteristics. TM rich,
In either case of RE rich, the saturation value of the Kerr rotation angle θk decreases due to the temperature rise of the magnetic field detection medium.

However, the change of the saturation magnetic field Hs is opposite between the TM rich and the RE rich, and due to this difference, the change amount of θk with respect to the change of the external magnetic field H _ext is large in RE rich and small in TM rich. That is, as the temperature rises, the sensitivity to the external magnetic field H _ext increases with RE rich and deteriorates with TM rich. Further, due to this difference, in the range where the external magnetic field H _ext is smaller than the saturation magnetic field Hs, the signal strength decreases in TM rich but increases in RE rich in some cases.

In this embodiment, it is relatively easy to raise the temperature of the magnetic field detecting medium by increasing the laser power at the time of detection, but it is difficult to lower the temperature. Therefore, when manufacturing the magnetic field detection medium, the saturation magnetic field Hs is increased by the TM rich and the RE rich.
It is necessary to take into account that the temperature dependence of the is different.

That is, in the case of TM rich, the composition is prepared in advance so that the value of the saturation magnetic field Hs becomes small, and the saturation magnetic field Hs is increased by increasing the temperature of the magnetic field detection medium by adjusting the laser power and the like. By adjusting the laser power and the like to raise the temperature of the magnetic field detection medium to increase the saturation magnetic field Hs. It is necessary to reduce Hs to a predetermined value. In other words, it is necessary to determine the composition in consideration of the temperature rise of the magnetic field detection medium.

However, when the RE rich one is used, it is important to use a composition having no compensation temperature in the magnetic field detection temperature region. This is because the coercive force becomes infinite at the compensation temperature, and the coercive force becomes considerably large even at a temperature in the vicinity thereof, so that the magnetization of the magnetic field detection medium does not reverse in a recording magnetic field of several hundred Oe, and the magnetic field detection is performed. This is because it will not function as a medium for use.

From the above, both TM-rich and RE-rich have advantages and disadvantages, and it cannot be said that which one is generally good and which one should be selected according to the purpose.

[0083]

According to the present invention, even for a magnetic head such as a head element of a levitation type magnetic head in which a magnetic field generation region is extremely narrow, the position adjustment of the magnetic head with respect to a light spot can be performed very easily and reliably. This makes it possible to significantly improve the yield and reliability of products.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing the structure of a magneto-optical disk used in this example.

FIG. 2 is a characteristic diagram showing the relationship between the composition, the coercive force, and the saturation magnetization in the magnetic layer.

FIG. 3 is a characteristic diagram showing temperature dependence of coercive force of the magneto-optical disk used in this example.

FIG. 4 is a characteristic diagram showing temperature dependence of a Kerr rotation angle of a magneto-optical disk.

FIG. 5 is a perspective view schematically showing how the position of the flying magnetic head is adjusted in this embodiment.

FIG. 6 is a flowchart showing a work process for adjusting the position of the flying magnetic head.

FIG. 7 is a characteristic diagram showing the relationship between the position of the head element and the RF output amplitude.

FIG. 8 is a characteristic diagram showing a relationship between a recording magnetic field and the number of errors.

FIG. 9 is a characteristic diagram showing the relationship between the external magnetic field and the Kerr rotation angle when the squareness ratio is smaller than 1 in the TM rich composition.

FIG. 10 is a characteristic diagram showing a relationship between an external magnetic field and a Kerr rotation angle in the case of a TM-rich composition and a squareness ratio of 1.

FIG. 11 is a characteristic diagram showing a relationship between an external magnetic field and a Kerr rotation angle in the case of a RE-rich composition and a squareness ratio of 1.

FIG. 12 is a characteristic diagram showing the relationship between the external magnetic field and the Kerr rotation angle when the squareness ratio is less than 1 in the RE-rich composition.

FIG. 13 is a pp of the Kerr rotation angle when the squareness ratio is 1.
It is a characteristic view which shows a value.

FIG. 14 is a characteristic diagram showing a magnetic field distribution of a magnetic head with respect to an external magnetic field.

FIG. 15 is a characteristic diagram showing the relationship between the position of the head element and the RF output amplitude.

FIG. 16 is a characteristic diagram showing the pp value of the Kerr rotation angle when the squareness ratio is less than 1.

FIG. 17 is a characteristic diagram showing the relationship between the drive current of the magnetic head and the RF output amplitude.

FIG. 18 is a characteristic diagram showing the relationship between the external magnetic field and the Kerr rotation angle when the external magnetic field <saturation magnetization.

FIG. 19 is a characteristic diagram showing the relationship between the position of the head element and the RF output amplitude.

FIG. 20 is a characteristic diagram showing temperature dependence of a Kerr hysteresis loop in TM rich.

FIG. 21 is a characteristic diagram showing the temperature dependence of the Kerr hysteresis loop in RE rich.

FIG. 22 is a characteristic diagram showing the relationship between the external magnetic field in TM rich and the pp value of RF output amplitude.

FIG. 23 is a characteristic diagram showing a relationship between an external magnetic field in RE rich and a pp value of RF output amplitude.

[Brief description of reference numerals]

 11 mechanical deck 12 floating magnetic head 13 substrate 14 magnet head drive substrate 15 high frequency level meter 16 EFM generating means 17 head moving means 18 disk cartridge 21 head arm 22 head element

Claims (15)

[Claims] 1. A magnetic layer having one or more magnetic layers having perpendicular magnetic anisotropy, wherein the magnetic layer can change its magnetization direction according to an external magnetic field at a magnetic field detection temperature of room temperature or higher and lower than Curie temperature. A magnetic field detecting medium, which exhibits a detectable magneto-optical effect together with a change in the magnitude of an external magnetic field applied to the magnetic layer due to the change in the magneto-optical effect. 2. The magnetic field detecting medium according to claim 1, wherein the magnetization direction in the magnetic layer can be changed by an external magnetic field of 200 Oersted or less. 3. The magnetic field detecting medium according to claim 1, wherein the value of saturation magnetization in the magnetic layer is larger than the value of residual magnetization. 4. The magnetic field according to claim 3, wherein the magnitude of the magnetic field necessary for saturating the magnetization of the magnetic layer is equal to or higher than the maximum value of the applied external magnetic field in the vicinity of the magnetic field detection temperature. Medium for magnetic field detection. 5. The magnetic field detecting medium according to claim 1, which is a disk-shaped medium having a magnetic layer formed on a transparent disk-shaped substrate. 6. The medium for magnetic field detection according to claim 1, wherein the magnetic layer has at least one rare earth-transition metal amorphous thin film. 7. The magnetic layer has a composition in which a compensation temperature is equal to or lower than room temperature and a sublattice magnetization of a transition metal element is larger than a sublattice magnetization of a rare earth element in a magnetic field detection temperature region. 6. The magnetic field detection medium according to 6. 8. The magnetic layer has a composition in which there is no compensation temperature in the magnetic field detection temperature region and the sublattice magnetization of the rare earth element is larger than the sublattice magnetization of the transition metal. Magnetic field detection medium. 9. The magnetic layer contains at least G as a rare earth element.
7. The magnetic field detecting medium according to claim 6, wherein the medium contains d. 10. The magnetic field detecting medium according to claim 6, wherein the magnetic layer contains at least Fe and Co as transition metal elements. 11. At least one magnetic layer having perpendicular magnetic anisotropy is provided, and the magnetic layer can change its magnetization direction depending on an external magnetic field at a magnetic field detection temperature of room temperature or higher and lower than Curie temperature. By using a magnetic field detection medium that exhibits a possible magneto-optical effect, moving a magnetic head that generates a predetermined recording magnetic field on the magnetic field detection medium, and detecting the magneto-optical effect that changes at that time as a reproduction signal. A method of adjusting the position of a magnetic head, which comprises finding a maximum magnetic field generation position of the magnetic head with respect to a light spot. 12. The value of saturation magnetization of the magnetic layer of the magnetic field detection medium is set larger than the value of residual magnetization, and the magnitude of the recording magnetic field of the magnetic head is the magnitude of the magnetic field required to saturate the magnetization of the magnetic layer. 12. The method of adjusting the position of a magnetic head according to claim 11, wherein the following is set. 13. Amplitude of reproduced signal, number of errors, or C /
2. The maximum magnetic field generation position of the magnetic head with respect to the light spot is found by detecting N.
1. The magnetic head position adjusting method described in 1. 14. The method of adjusting the position of a magnetic head according to claim 11, wherein the position of the magnetic head is adjusted in a state where the optical pickup and the magnetic head are provided in the magneto-optical recording / reproducing apparatus. 15. The magnetic head position adjusting method according to claim 11, wherein the magnetic head is a floating magnetic head.