JP2012155796A - Initialization method of perpendicular magnetic recording medium, initialization device, and perpendicular magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an initialization method of a perpendicular magnetic recording medium optimizing servo characteristics thereof in a short time.SOLUTION: An initialization method of a perpendicular magnetic recording medium for initializing the perpendicular magnetic recording medium having coercive force of Hc and a nuclear generating magnetic field of Hn comprises: an arranging step for arranging the perpendicular magnetic recording medium at a predetermined position; and a magnetic field applying step, in which magnetic field applying means having an electromagnet or a permanent magnet applies a DC magnetic field Ha to the perpendicular magnetic recording medium. In the magnetic field applying step, the initialization method of the perpendicular magnetic recording medium applies the DC magnetic field Ha to the perpendicular magnetic recording medium such that Hah and Haz satisfy the following expressions: Haz/Hn≤1.17 and Hah/Hc≥1.3, where Hah represents a horizontal direction magnetic field component being a component parallel to a surface of the perpendicular magnetic recording medium and Haz represents a perpendicular direction magnetic field component being a component perpendicular thereto, both of which are out of components of the DC magnetic field Ha.

Description

  The present invention relates to an initialization method, an initialization device, and a perpendicular magnetic recording medium for a perpendicular magnetic recording medium, and in particular, perpendicular magnetic recording of a magnetic information pattern such as format information on a perpendicular magnetic recording disk used in a hard disk device or the like. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for initializing a perpendicular magnetic recording medium, an initialization apparatus, and a perpendicular magnetic recording medium initialized by this initialization method.

  In recent years, magnetic disks (hard disks) used in hard disk drives (hereinafter referred to as HDDs), which are rapidly spreading, have been format information and address information after being delivered to drive manufacturers from magnetic disk manufacturers and before being incorporated into drives. Is generally written.

  Magnetic recording media such as magnetic disks are classified into in-plane magnetic recording media having an easy axis in the plane of the magnetic layer and perpendicular magnetic recording media having an easy axis in the direction perpendicular to the surface of the magnetic layer. The

  Conventionally, in-plane magnetic recording media have been used, but recently, perpendicular magnetic recording media advantageous for improving recording density (increasing storage capacity) and perpendicular magnetic recording methods for perpendicular magnetic recording media have been developed. And is being introduced to the market.

  As a technique indispensable as a stage before the introduction of such a perpendicular magnetic recording method, there is a method for initializing a perpendicular magnetic recording medium (hereinafter sometimes simply referred to as a magnetic recording medium or a medium). Generally, there are a DC demagnetization method and an AC demagnetization method as methods for initializing a magnetic recording medium.

  The DC demagnetization method is a demagnetization method in which a magnetic field is demagnetized by applying a DC magnetic field in a direction perpendicular to the surface thereof. When this DC demagnetization is performed, the magnetic moment contained in the magnetic layer in the magnetic recording medium becomes perpendicular to the medium surface, and the directions of the S and N poles are aligned in one direction. Here, the demagnetization in which the directions of the S and N poles are aligned in one direction is hereinafter referred to as “one-way demagnetization”.

  The AC demagnetization method is a demagnetization method in which a magnetic recording medium is demagnetized by applying an AC magnetic field in a direction perpendicular to the surface thereof. Normally, AC demagnetization is performed by applying an AC magnetic field at a frequency twice or more of the minimum signal recorded in the HDD and recording the magnetization. When the AC demagnetized portion is reproduced by a reproducing head, the magnetic properties in the magnetic recording medium In order to read the S and N poles of the magnetic moment of the layer almost simultaneously, the total amount of magnetic moment is effectively measured close to zero.

  Further, Non-Patent Document 1 discloses a demagnetizing method in which a magnetic field is applied in parallel to the surface of a perpendicular magnetic recording medium, not perpendicularly. Non-Patent Document 1 describes an AC demagnetization method for the entire surface by applying an external magnetic field and its characteristic results.

IEEE Transactions on magnetics, vol. 41 (2005) 3127. “Bulk AC-Er assure Technique for Perpendicular Recording Media: Effect of Exchange Coupling” EN Abarra, Paramjit Gill, BR Acharya, J. Zhou, M. Zheng, G. Choe , and B. Demczyk.

  In the case of the degaussing method by applying a parallel magnetic field as shown in Non-Patent Document 1, the magnetic moment contained in the magnetic layer in the magnetic recording medium is applied to the surface of the medium following the parallel magnetic field during the application of the parallel magnetic field. When the parallel magnetic field is turned off and the application of the parallel magnetic field is stopped, rearrangement of the magnetic moment occurs, the directions of the south and north poles are random, and the amount of magnetization remaining in the magnetic layer in the magnetic recording medium becomes zero. . Here, the demagnetization in which the directions of the S pole and the N pole are random is hereinafter referred to as “random demagnetization”.

  However, Non-Patent Document 1 discloses only a brief description of the demagnetization method and the characteristic results thereof, and the demagnetization of the perpendicular magnetic recording medium that can be actually applied to the product only by the disclosed contents. It was impossible to perform (initialization).

  In order to perform degaussing by applying a magnetic field parallel to the surface of a perpendicular magnetic recording medium as described in Non-Patent Document 1 through intensive research by the present inventors, it is not described in Non-Patent Document 1. I found that I needed to solve some problems.

  The issues are as follows. That is, it is extremely difficult to apply only a magnetic field parallel to the surface of the magnetic recording medium (referred to as a horizontal magnetic field) to the magnetic recording medium in practice. It is applied including the component. When a magnetic field including a perpendicular magnetic field component is applied to the magnetic recording medium, demagnetization is impossible depending on the magnitude of the perpendicular magnetic field component.

  Also, the magnitude of the horizontal magnetic field component has a great influence on demagnetization.

  Furthermore, the inventors have intensively researched and found that the initialized magnetization state of the perpendicular magnetic recording medium affects the servo characteristics. An initial magnetization method for optimizing the servo characteristics has not been known in the past, but the present inventors have invented an initialization method for optimizing the servo characteristics.

  In view of such circumstances, the present invention is intended to provide an initialization method, an initialization device, and a perpendicular magnetic recording medium for a perpendicular magnetic recording medium that can be initialized in a short time and have good servo characteristics.

  The problems of the present invention can be solved by the following inventions.

  That is, the perpendicular magnetic recording medium initialization method of the present invention is an initialization method for a perpendicular magnetic recording medium for initializing a perpendicular magnetic recording medium having a coercive force of Hc and a nucleation magnetic field of Hn. An arrangement step of arranging the perpendicular magnetic recording medium at a predetermined position; and a magnetic field applying step in which a magnetic field applying means having an electromagnet or a permanent magnet applies a DC magnetic field Ha to the perpendicular magnetic recording medium, In the applying step, among the components of the DC magnetic field Ha, the horizontal magnetic field component that is parallel to the surface of the perpendicular magnetic recording medium is Hah, and the vertical magnetic field component that is vertical is Haz. The main feature is that the DC magnetic field Ha is applied to the perpendicular magnetic recording medium so that Hn ≦ 1.17 and Hah / Hc ≧ 1.3.

  Thereby, the perpendicular magnetic recording medium can be randomly demagnetized in a short time, and the servo characteristics of the perpendicular magnetic recording medium can be improved.

  In the initialization method of the perpendicular magnetic recording medium of the present invention, in the arranging step, the perpendicular magnetic recording medium is configured such that one of the two surfaces faces the magnetic field applying means and the other surface is the other surface. And arranged so as to face a second magnetic field applying means for applying a DC magnetic field Ha2 to the perpendicular magnetic recording medium, which has an electromagnet or a permanent magnet. In the magnetic field applying step, the second magnetic field applying means When the horizontal magnetic field component that is parallel to the surface of the perpendicular magnetic recording medium is Hah2 and the vertical magnetic field component that is a vertical component is Haz2, among the components of the DC magnetic field Ha2, Haz2 / Hn2 ≦ 1.17 And applying the Ha2 to the perpendicular magnetic recording medium so that Hah2 / Hc2 ≧ 1.3 and the Hah2 is in the same direction as the Hah in the perpendicular magnetic recording medium. It has a feature.

  As a result, random demagnetization with better demagnetization characteristics can be performed on the perpendicular magnetic recording medium, and the servo characteristics of the perpendicular magnetic recording medium can be further improved.

  Further, the initialization method of the perpendicular magnetic recording medium of the present invention is an initialization method of a perpendicular magnetic recording medium for initializing a perpendicular magnetic recording medium having a coercive force of Hc and a nucleation magnetic field of Hn. An arrangement step of arranging the perpendicular magnetic recording medium at a predetermined position; and a magnetic field applying step in which a magnetic field applying means having an electromagnet or a permanent magnet applies a DC magnetic field Ha to the perpendicular magnetic recording medium, In the applying step, among the components of the DC magnetic field Ha, the horizontal magnetic field component that is parallel to the surface of the perpendicular magnetic recording medium is Hah, and the vertical magnetic field component that is vertical is Haz. The main feature is that the DC magnetic field Ha is applied to the perpendicular magnetic recording medium so that Hn ≦ 1.2 and Hah / Hc ≧ 1.5.

  Thereby, the perpendicular magnetic recording medium can be randomly demagnetized in a short time, and the servo characteristics of the perpendicular magnetic recording medium can be improved.

  Furthermore, according to the initialization method of the perpendicular magnetic recording medium of the present invention, in the arranging step, one of the two surfaces of the perpendicular magnetic recording medium faces the magnetic field applying means, and the other surface. Is arranged so as to face a second magnetic field applying means for applying a DC magnetic field Ha2 to the perpendicular magnetic recording medium, which has an electromagnet or a permanent magnet, and in the magnetic field applying step, the second magnetic field applying means However, among the components of the DC magnetic field Ha2, when the horizontal magnetic field component that is parallel to the surface of the perpendicular magnetic recording medium is Hah2, and the vertical magnetic field component that is the vertical component is Haz2, Haz2 / Hn ≦ Mainly applying Ha2 to the perpendicular magnetic recording medium such that 1.2 and Hah2 / Hc ≧ 1.5, and in the perpendicular magnetic recording medium, the Hah2 is in the same direction as the Hah. Features.

  As a result, random demagnetization with better demagnetization characteristics can be performed on the perpendicular magnetic recording medium, and the servo characteristics of the perpendicular magnetic recording medium can be further improved.

  The perpendicular magnetic recording medium initialization apparatus of the present invention is an initialization apparatus for a perpendicular magnetic recording medium for initializing a perpendicular magnetic recording medium having a coercive force of Hc and a nucleation magnetic field of Hn. A magnetic field applying means for applying a DC magnetic field Ha to the perpendicular magnetic recording medium, the magnetic field applying means being disposed opposite one surface of the perpendicular recording medium, When Hah is a horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium and Haz is a vertical magnetic field component that is a vertical component, Haz / Hn ≦ 1.17 and Hah / Hc ≧ 1.3 In addition, the main feature is that the magnitude of the DC magnetic field Ha and the relative position of the magnetic field applying means with respect to the perpendicular magnetic recording medium are adjusted.

  Thereby, the perpendicular magnetic recording medium can be randomly demagnetized in a short time, and the servo characteristics of the perpendicular magnetic recording medium can be improved.

  The perpendicular magnetic recording medium initialization apparatus of the present invention further comprises second magnetic field applying means for applying a DC magnetic field Ha2 to the perpendicular recording medium, wherein the second magnetic field applying means is the perpendicular magnetic recording means. A horizontal magnetic field that is disposed opposite to a surface of the recording medium on which the magnetic field applying unit is not disposed and is a component parallel to the surface of the perpendicular magnetic recording medium among the components of the DC magnetic field Ha2. When the component is Hah2 and the vertical magnetic field component that is a vertical component is Haz2, Haz2 / Hn ≦ 1.17 and Hah2 / Hc ≧ 1.3, and Ha2 and Ha are in the same direction in the perpendicular magnetic recording medium The main feature is that the magnitude of the DC magnetic field Ha2 and the relative position of the second magnetic field applying means with respect to the perpendicular magnetic recording medium are adjusted.

  Thereby, the perpendicular magnetic recording medium can be randomly demagnetized in a short time, and the servo characteristics of the perpendicular magnetic recording medium can be improved.

  The perpendicular magnetic recording medium initialization apparatus of the present invention is an initialization apparatus for a perpendicular magnetic recording medium for initializing a perpendicular magnetic recording medium having a coercive force of Hc and a nucleation magnetic field of Hn. A magnetic field applying means for applying a DC magnetic field Ha to the perpendicular magnetic recording medium, the magnetic field applying means being disposed opposite one surface of the perpendicular recording medium, When the horizontal magnetic field component parallel to the surface of the perpendicular magnetic recording medium is Hah and the vertical magnetic field component vertical is Haz, Haz / Hn ≦ 1.2 and Hah / Hc ≧ 1.5. In addition, the main feature is that the magnitude of the DC magnetic field Ha and the relative position of the magnetic field applying means with respect to the perpendicular magnetic recording medium are adjusted.

  Thereby, the perpendicular magnetic recording medium can be randomly demagnetized in a short time, and the servo characteristics of the perpendicular magnetic recording medium can be improved.

  Furthermore, the perpendicular magnetic recording medium initialization apparatus of the present invention further comprises second magnetic field applying means for applying a DC magnetic field Ha2 to the perpendicular recording medium, wherein the second magnetic field applying means is the perpendicular magnetic recording medium. A horizontal direction that is disposed opposite to a surface of the magnetic recording medium on which the magnetic field applying unit is not disposed and is a component parallel to the surface of the perpendicular magnetic recording medium among the components of the DC magnetic field Ha2. When the magnetic field component is Hah2 and the vertical magnetic field component, which is a vertical component, is Haz2, Haz2 / Hn ≦ 1.2 and Hah2 / Hc ≧ 1.5, and Ha2 and Ha are the same in the perpendicular magnetic recording medium. The main feature is that the magnitude of the DC magnetic field Ha2 and the relative position of the second magnetic field applying means with respect to the perpendicular magnetic recording medium are adjusted so as to be oriented.

  As a result, random demagnetization with better demagnetization characteristics can be performed on the perpendicular magnetic recording medium, and the servo characteristics of the perpendicular magnetic recording medium can be further improved.

  The perpendicular magnetic recording medium initialization apparatus according to the present invention is mainly characterized in that the distance between the south pole and the north pole of the magnetic field applying means is equal to or larger than the diameter of the perpendicular magnetic recording medium.

  Thereby, a horizontal magnetic field can be applied to the entire radial direction of the perpendicular magnetic recording medium, and the ratio of the perpendicular magnetic field can be reduced, so that random demagnetization of the perpendicular magnetic recording medium can be performed faster, and Random demagnetization characteristics can be improved.

  Further, the perpendicular magnetic recording medium initialization apparatus of the present invention is such that the distance between the south pole and the north pole of the magnetic field applying means is not less than the diameter of the perpendicular magnetic recording medium, and the second magnetic field applying means. The main feature is that the distance between the S pole and the N pole is equal to or larger than the diameter of the perpendicular magnetic recording medium.

  Thereby, a horizontal magnetic field can be applied to the entire radial direction of the perpendicular magnetic recording medium, and the ratio of the perpendicular magnetic field can be reduced, so that random demagnetization of the perpendicular magnetic recording medium can be performed faster, and Random demagnetization characteristics can be improved.

  Furthermore, the perpendicular magnetic recording medium of the present invention is a perpendicular magnetic recording medium that has been initialized by the above-described perpendicular magnetic recording medium initialization method and then written with a servo signal. The main feature of the present invention is to maintain a randomly demagnetized magnetization state.

  Thereby, a perpendicular magnetic recording medium with good servo characteristics can be provided.

It is the schematic of the initialization apparatus of the 1st Embodiment of this invention. It is the schematic of the initialization apparatus of the 2nd Embodiment of this invention. It is the schematic of the initialization apparatus of the 3rd Embodiment of this invention. It is the schematic of the initialization apparatus of the 4th Embodiment of this invention. 3 is a schematic diagram illustrating a vertical component and a horizontal component of a magnetic field applied to the inside of a medium 103. FIG. It is the figure which showed the MH curve of the perpendicular magnetization medium. FIG. 4 is a diagram showing an SN ratio after applying a horizontal magnetic field to the medium 1. FIG. 6 is a diagram showing the SN ratio after applying a horizontal magnetic field to the medium 2. FIG. 4 is a diagram showing an SN ratio after applying a horizontal magnetic field to the medium 3. FIG. 4 is a diagram showing an SN ratio after applying a vertical magnetic field to the medium 1. FIG. 6 is a diagram showing an SN ratio after applying a vertical magnetic field to the medium 2. FIG. 6 is a diagram showing the SN ratio after applying a vertical magnetic field to the medium 3. It is explanatory drawing explaining the conventional burst A and B part which recorded the high frequency signal in the part between tracks. It is explanatory drawing explaining the burst pattern recorded on a medium, Comprising: The part between tracks is a random demagnetization state. It is a figure which shows a servo following performance evaluation result. It is a figure showing the spectrum which carried out the Fourier-transform. It is explanatory drawing for demonstrating a major loop. It is explanatory drawing for demonstrating a major loop. It is explanatory drawing for demonstrating a major loop. It is a figure which shows the determination method of a random demagnetization state. It is a figure which shows the determination method of one-way demagnetization. It is the schematic of the apparatus which performed unidirectional demagnetization.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Here, in the drawing, portions indicated by the same symbols are similar elements having similar functions. In addition, in the present specification, when a numerical range is expressed using “˜”, upper and lower numerical values indicated by “˜” are also included in the numerical range.

<Configuration of initialization apparatus for perpendicular magnetic recording medium>
An embodiment of an initialization apparatus for a perpendicular magnetic recording medium according to the present invention (hereinafter sometimes simply referred to as an initialization apparatus) will be described with reference to the drawings. FIG. 1 is a schematic diagram of an initialization apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic diagram of an initialization apparatus according to the second embodiment of the present invention. FIG. 3 is a schematic diagram of an initialization apparatus according to the third embodiment of the present invention. FIG. 4 is a schematic diagram of an initialization apparatus according to the fourth embodiment of the present invention.

  An initialization apparatus according to a first embodiment of the present invention will be described. As shown in FIG. 1, the initialization apparatus 100 according to the first embodiment of the present invention rotates two electromagnets 110 and 120 and a disk-shaped medium (perpendicular magnetic recording medium) 130 to be initialized. The two electromagnets 110 and 120 are arranged to face each other across the surface of the medium 130 to be initialized.

  The electromagnet 110 mainly includes a substantially C-shaped core 112, a coil 114 wound around the core 112, and current supply means 118 for supplying a current to the coil 114. Both ends of the core 112, that is, the distance between the N pole and the S pole of the electromagnet 110 is configured to be larger than the diameter of the medium 130. As a result, most of the magnetic field components applied to the medium 130 can be changed to the magnetic field 116 parallel to the surface of the medium 130. Therefore, it is possible to reduce the magnetic field perpendicular to the surface of the medium 130 as much as possible.

  Similarly, the electromagnet 120 mainly includes a substantially C-shaped core 122, a coil 124 wound around the core 122, and current supply means 128 for supplying a current to the coil 124. The interval between the two end portions of the core 122 is configured to be larger than the diameter of the medium 130. Thereby, most of the components of the magnetic field applied to the medium 130 can be changed to the magnetic field 126 parallel to the surface of the medium 130. Therefore, it is possible to reduce the magnetic field perpendicular to the surface of the medium 130 as much as possible.

  In addition, the electromagnet 110 and the electromagnet 120 are installed so that the same polarities at the respective leading ends are opposed to each other with the surface of the medium 130 interposed therebetween, and the magnetic field generated by the electromagnet 110 and the electromagnet 120 is the same in the medium 130 Configured to be in the direction. As a result, the effect of repelling the lines of magnetic force generated from the opposing magnets is generated, and the vertical components of the magnetic fields generated from the opposing magnets cancel each other. Can be prevented from being applied to the medium 130, and a magnetic field parallel to the surface of the medium 130 (hereinafter, sometimes simply referred to as a parallel magnetic field) is applied to the medium 130. It becomes possible to do.

  In the present embodiment, two electromagnets are used, but the problem of the present invention can be solved even if only one electromagnet is used. However, this embodiment in which two electromagnets are used so as to face each other is preferable because the vertical magnetic field can be further reduced.

  When only one electromagnet is used, the medium 130 may be installed between the N pole and the S pole of the electromagnet, or from the position between the N pole and the S pole of the electromagnet. A 130 medium may be installed at a position away from the electromagnet in a direction perpendicular to a straight line connecting the N pole and the S pole.

  Next, an initialization apparatus according to the second embodiment of the present invention will be described. The content different from the first embodiment will be described, and the description of the same content will be omitted.

  As shown in FIG. 2, an initialization apparatus 200 according to the second embodiment of the present invention uses two permanent magnets 210 and 220 instead of electromagnets in the first embodiment. That is, the initialization apparatus 200 includes two permanent magnets 210 and 220 and a rotating means (not shown) for rotating a disk-shaped medium (perpendicular magnetic recording medium) 130 to be initialized. The two permanent magnets 210 and 220 are arranged to face each other across the surface of the medium 130 to be initialized.

  The distance between the south pole and the north pole at both ends of the permanent magnet 210 and the distance between the south pole and the north pole of the permanent magnet 220 are configured to be equal to or larger than the diameter of the medium 130. Thereby, most of the components of the magnetic field applied to the medium 130 can be changed to the magnetic fields 216 and 226 parallel to the surface of the medium 130. Therefore, it is possible to reduce the magnetic field perpendicular to the surface of the medium 130 as much as possible.

  In addition, the permanent magnet 210 and the permanent magnet 220 are installed so that the same poles of the respective tip portions face each other across the surface of the medium 130, and the magnetic field generated by the permanent magnet 210 and the permanent magnet 220 is a medium. It is comprised so that it may become the same direction in 130. FIG. As a result, the magnetic lines of force generated from the opposing magnets repel each other, and the vertical components of the magnetic fields generated from the opposing magnets cancel each other, so that the vertical magnetic field is applied to the medium 130. This makes it possible to apply a parallel magnetic field to the medium 130.

  Here, instead of the two permanent magnets, one can use the permanent magnet, and the other can use the electromagnet.

  In the present embodiment, two permanent magnets are used. However, it is possible to solve the problem of the present invention using only one permanent magnet. However, the present embodiment in which two permanent magnets are used so as to face each other is preferable because the vertical magnetic field can be further reduced.

  When only one permanent magnet is used, the medium 130 may be installed between the north pole and the south pole of the permanent magnet, or between the north pole and the south pole of the permanent magnet. The medium 130 may be installed at a position away from the permanent magnet in a direction perpendicular to a straight line connecting the N pole and the S pole from the position.

  Next, an initialization apparatus according to the third embodiment of the present invention will be described. Since the initialization apparatus of the third embodiment is almost the same as the initialization apparatus of the first embodiment, the contents different from those of the first embodiment will be described, and the description of the same contents will be omitted.

  As shown in FIG. 3, the initialization apparatus 300 according to the third embodiment of the present invention has an interval between both ends of the core 312 and an interval between both ends of the core 322 as compared with the first embodiment. However, it is configured so as to be smaller than the diameter of the medium 130, and the rest is the same as in the first embodiment.

  That is, the initialization apparatus 300 according to the third embodiment of the present invention has two electromagnets 310 and 320 and a rotating unit (rotating means for rotating a disk-shaped medium (perpendicular magnetic recording medium) 130 to be initialized). The two electromagnets 310 and 320 are arranged to face each other across the surface of the medium 130 to be initialized.

  The electromagnet 310 mainly includes a substantially C-shaped core 312, a coil 314 wound around the core 312, and current supply means 318 for supplying current to the coil 314. The interval between the two end portions of the core 112 is configured to be smaller than the diameter of the medium 130.

  Thereby, enlarging of an apparatus can be prevented. However, the first embodiment is preferable in terms of increasing the ratio of the horizontal magnetic field among the components of the magnetic field applied to the medium 130.

  In addition, the electromagnet 310 and the electromagnet 320 are installed so that the same polarities at the respective tip portions are opposed to each other with the surface of the medium 130 interposed therebetween, and the magnetic field generated by the electromagnet 310 and the electromagnet 320 is the same in the medium 130. Configured to be in the direction. As a result, as in the first embodiment, the effect of repelling the lines of magnetic force generated from the opposing magnets is obtained, and the vertical component of the magnetic field generated from the opposing magnets cancels each other. Can do.

  Next, an initialization apparatus according to the fourth embodiment of the present invention will be described. Since the initialization apparatus of the fourth embodiment is almost the same as the initialization apparatus of the second embodiment, the contents different from those of the second embodiment will be described, and the description of the same contents will be omitted.

  As shown in FIG. 4, in the initialization device 400 of the fourth embodiment of the present invention, the distance between the south pole and the north pole of both ends of the permanent magnet 410 in the second embodiment is the diameter of the medium 130. The other configuration is the same as in the second embodiment.

  In other words, the initialization apparatus 400 is mainly configured by two permanent magnets 410 and 420 and a rotation means (not shown) for rotating the medium 130 to be initialized. Magnets 410 and 420 are arranged to face each other across the surface of disk-shaped medium 130 to be initialized.

  The distance between the S pole and the N pole at both ends of the permanent magnet 410 and the distance between the S pole and the N pole at both ends of the permanent magnet 420 are configured to be smaller than the diameter of the medium 130. . Thereby, enlarging of an apparatus can be prevented.

  In addition, the permanent magnet 410 and the permanent magnet 420 are installed so that the same poles of the respective tip portions face each other across the surface of the medium 130, and the magnetic field generated by the permanent magnet 410 and the permanent magnet 420 is the medium. It is comprised so that it may become the same direction in 130. FIG. As a result, the magnetic lines of force generated from the opposing magnets repel each other, and the vertical components of the magnetic fields generated from the opposing magnets cancel each other, so that the vertical magnetic field is applied to the medium 130. This makes it possible to apply a parallel magnetic field to the medium 130.

  In the present embodiment, two permanent magnets are used. However, it is possible to solve the problem of the present invention using only one permanent magnet. However, the present embodiment in which two permanent magnets are used so as to face each other is preferable because the vertical magnetic field can be further reduced.

<Operation of initialization device for perpendicular magnetic recording medium>
Next, the operation of the perpendicular magnetic recording medium initialization apparatus according to the present invention will be described with reference to the drawings.

  With reference to FIG. 1, the current supply means 118 and 128 supply a direct current to the coils 114 and 124, whereby the electromagnets 110 and 120 generate a magnetic field. The generated magnetic field is applied in the medium 130 installed between the electromagnet 110 and the electromagnet 120. The medium 130 may be applied with a magnetic field while being rotated by a rotating means (not shown). At this time, the magnetic field generated by the electromagnet 110 and the magnetic field generated by the electromagnet 120 are magnetic fields in a direction parallel to the surface of the medium 130 and are magnetic fields in the same direction in the medium 130.

  Here, in order to apply a magnetic field in a direction parallel to the surface of the medium 130 to the medium 130, a current supplied to the electromagnets 110 and 120 is controlled by a control unit (not shown), or the electromagnets 110 and 120 and the medium 130 are controlled. Can be performed by adjusting the positional relationship with the adjusting means (not shown).

  In addition, the current control by these control means and the position adjustment by the adjustment means are performed by monitoring the magnitude of the horizontal magnetic field component and the vertical magnetic field component of the applied magnetic field by a magnetic sensor (not shown), and each magnetic field component has a predetermined magnetic field strength. Can be controlled and adjusted.

  When a magnetic field parallel to the surface of the medium 130 is applied in the medium 130, the magnetic moment included in the magnetic layer in the medium 130 follows the in-plane direction, and after removing the applied magnetic field, each magnetic moment is removed. Returns to the direction perpendicular to the surface of the medium 130. At this time, the magnetic moments are not aligned in one direction and are perpendicular to the surface of the medium 130, but the direction of the magnetic moment is random. That is, the medium 130 is randomly demagnetized.

  Here, the initialization device of the third embodiment shown in FIG. 3 operates in the same manner as the initialization device of the first embodiment shown in FIG. The initialization devices of the second embodiment and the fourth embodiment shown in FIGS. 2 and 4 use the permanent magnet instead of the electromagnet, and the operation itself is the same. To do.

<Vertical and horizontal magnetic field application evaluation>
Next, the relationship between the vertical component and horizontal component of the magnetic field for initialization applied to the medium 130 and the SN ratio will be described. As a result of diligent research, the inventors of the present invention have applied only a magnetic field (horizontal magnetic field) parallel to the surface of the medium 103 to the inside of the medium 103, and the ratio of the horizontal magnetic field to 100% of the applied magnetic field components is 100%. It was difficult to do, and in practice, it was found that a magnetic field perpendicular to the medium surface (vertical magnetic field) was included.

  Here, it demonstrates using FIG. FIG. 5 is a schematic diagram showing a vertical component and a horizontal component of a magnetic field applied to the inside of the medium 103. As shown in FIG. 5, even when a DC magnetic field Ha for initialization (for demagnetization) is applied to the inside of the medium 103, in most cases, the magnetic field Ha has a certain angle α with respect to the plane of the medium 103. Is applied. For this reason, Ha has a horizontal magnetic field component Hah and a vertical magnetic field component Haz.

  The relationship between the vertical magnetic field component Haz and the horizontal magnetic field component Hah and the SN ratio was evaluated as follows.

(1) Production of medium As a medium, a CoCrPt film was formed on the surface of a glass disk having an outer diameter of 65 mm (2.5 inch type) by using a vacuum film forming apparatus, and a thin glass hard disk was produced. At this time, by adjusting the vacuum degree of the film forming apparatus, the pressure of the argon gas introduced into the film forming apparatus, the heating temperature of the glass disk, and the film thickness of the CoCrPt film, the coercive force Hc and the nucleation magnetic field Hn are varied. Such a glass hard disk (medium) was produced and designated as medium 1 to medium 3.

  The coercive force Hc and nucleation magnetic field Hn of the created media 1 to 3 are shown in Table 1 below. A plurality of media 1 to 3 were produced. The media 1 to 3 are also used for servo following performance evaluation described later.

また、上記真空成膜装置の成膜条件の一例を下記に示す。
・成膜装置の真空度 １．３３×１０^−５Pa（１０^−７Torr）
・成膜装置にアルゴンガス導入後の真空度 ０．４Pa（３×１０^−３Torr）
・ガラス板加熱温度 ２００℃
・CoCrPtの膜厚 ２５ｎｍ
・磁束密度 ５．７Ｔ（４５００Gauss）
・保磁力Hc １９９ｋA/m
ここで、核発生磁界Hnについて図６を参照して説明する。図６は、垂直磁化媒体のM-Hカーブを示した図である。垂直磁化媒体についてVSM等でM-Hカーブの測定をすると、図６に示すようなヒステリシスカーブを示す。ここで、VSMとは、試料振動型磁力計(Vibrating Sample Magnetometer)のことであり、均一磁場中においた試料を一定の周波数・振幅で振動させ、試料近辺に配置した検出コイルに誘起される起電力をロックインアンプにより検出することで試料の磁化量を測定する装置のことである。また、M-Hカーブとは、横軸にVSM測定における印加磁場H、縦軸に磁場印加時に試料に誘起された磁化量Mをとったときの磁化量Mの印加磁場H依存の曲線のことである。

An example of film forming conditions of the vacuum film forming apparatus is shown below.
・ Degree of vacuum of film forming apparatus 1.33 × 10 ⁻⁵ Pa (10 ⁻⁷ Torr)
· Deposition apparatus at a vacuum 0.4Pa after argon gas introduction (3 × ^{10 -3} Torr)
・ Glass plate heating temperature 200 ℃
・ CoCrPt film thickness 25nm
・ Magnetic flux density 5.7T (4500Gauss)
・ Coercive force Hc 199kA / m
Here, the nucleation magnetic field Hn will be described with reference to FIG. FIG. 6 is a diagram showing the MH curve of the perpendicular magnetization medium. When the MH curve of a perpendicular magnetization medium is measured with a VSM or the like, a hysteresis curve as shown in FIG. 6 is shown. Here, VSM is a vibrating sample magnetometer (Vibrating Sample Magnetometer), which vibrates a sample in a uniform magnetic field at a certain frequency and amplitude, and is induced by a detection coil arranged in the vicinity of the sample. It is a device that measures the amount of magnetization of a sample by detecting electric power with a lock-in amplifier. The MH curve is a curve depending on the applied magnetic field H of the magnetization M when the horizontal axis represents the applied magnetic field H in VSM measurement, and the vertical axis represents the magnetization M induced in the sample when the magnetic field is applied. .

  As shown in this figure, when a magnetic field is gradually applied in the + direction to a medium having a magnetization amount of −Mr, there is a point at which the magnetization amount of the medium starts to change, and the magnetic field strength at that point is expressed as a nucleation magnetic field or Called the nucleation magnetic field Hn. The nucleation magnetic field Hn is a magnetic field strength at which the direction of magnetization of the medium starts to follow the direction of the applied magnetic field.

(2) Recording of Evaluation Signal and Magnetization State Evaluation As an evaluation signal, a pattern signal having an L / S ratio of 1 was recorded on the media 1 to 3 using an STW (servo track writer). Here, the L / S ratio refers to the ratio of Line (+ signal) and Space (− signal).

  Next, using a TMR (Tunneling Magneto Resistance) reproducing head having a head gap of 0.03 μm and a track width of 0.055 μm, magnetization of media 1 to 3 using an electromagnetic conversion characteristic measuring device (manufactured by Kyodo Electronics: model number LS-90) The state was evaluated.

  Thereafter, the signal read by the electromagnetic conversion characteristic measuring apparatus was frequency-resolved using a spectrum analyzer, and the SN ratio was obtained from the peak intensity S of the primary signal and the extrapolated noise N. The signal-to-noise ratio of the obtained evaluation signal was 12 dB.

(3) Horizontal magnetic field application evaluation A DC magnetic field in a direction parallel to the surface of the medium was applied to each of the media 1 to 3, and the SN ratio after application was measured. The SN ratio was measured in the same manner as (2) above. The horizontal magnetic field was applied using the apparatus shown in FIG. 1 by changing the strength of the applied magnetic field, and the SN ratio of the medium was measured for each application of the magnetic field with the changed strength. Here, the SN ratio of the evaluation signals of the media 1 to 3 before applying the horizontal magnetic field is 12 dB as determined in the above (2).

  The evaluation results are shown in FIGS. FIG. 7 is a diagram illustrating the SN ratio after applying a horizontal magnetic field to the medium 1. FIG. 8 is a diagram showing the SN ratio after a horizontal magnetic field is applied to the medium 2. FIG. 9 is a diagram showing the SN ratio after a horizontal magnetic field is applied to the medium 3.

  7 to 9, the horizontal axis indicates the ratio between the applied horizontal magnetic field intensity Hah and the coercive force Hc of the medium, and the vertical axis indicates the SN ratio of the medium after the horizontal magnetic field is applied. As shown in FIGS. 7 to 9, in any medium 1 to 3 having different Hc and Hn, by applying a horizontal magnetic field having a Hah / Hc of 1.3 or more to the medium, the evaluation signal has an SN ratio. Was reduced to 2 dB or less, and it was found that the medium was surely demagnetized.

  In addition, by applying a horizontal magnetic field to the medium so that Hah / Hc is 1.5 or more, it was found that the signal for evaluation was reduced to an S / N ratio of 1 dB or less, and the medium was more reliably demagnetized. . From this evaluation result, it can be said that the strength of the DC horizontal magnetic field applied to the medium is preferably such that Hah / Hc is 1.3 or more, and more preferably 1.5 or more.

  Here, Hah / Hc represents the ratio of the applied magnetic field to the coercive force Hc of the medium, and by using this Hc ratio, random demagnetization can be performed when the horizontal magnetic field strength Hah of the applied magnetic field becomes a value. You can easily know what will happen.

  In addition, it was confirmed that the media 1 to 3 demagnetized by this evaluation were randomly demagnetized in which the directions of the N pole and the S pole varied randomly in the direction perpendicular to the medium surface. This confirmation was confirmed by performing a VSM measurement, so that the M-H curve of the medium had a path following a minor loop. It was also confirmed that the magnetization state of random demagnetization was a magnetization amount 0 by comparison with the major loop. In the case of unidirectional demagnetization, the M-H curve in this measurement overlaps the major loop.

  Here, further details will be described with reference to the drawings. 17 to 19 are explanatory diagrams for explaining the major loop. FIG. 20 is a diagram illustrating a method for determining a random demagnetization state. FIG. 21 is a diagram illustrating a method for determining unidirectional demagnetization.

  Referring to FIGS. 17 to 19, a major loop is a state in which a magnetic field having a magnetic field intensity until one saturation magnetization is generated (state (1)) (see FIG. 17), and then saturated in the reverse direction. A magnetic field having a reverse magnetic field strength is applied until magnetization is reached (state (2)) (see FIG. 18), and a magnetic field having a magnetic field strength until saturation magnetization is performed again in the first saturation magnetization direction (state (3)). = State (1)) (refer to FIG. 19) is a curve of change in magnetization state in (1) to (2) to (3).

  That is, referring to FIG. 17, when the initial state is the magnetization 0 (random demagnetization state), the magnetic field generated with the application of the magnetic field follows the path shown by the thick line in FIG. At this time, since the path is out of the major loop, it is called a minor loop.

  Next, referring to FIG. 18, when an applied magnetic field is applied in the minus direction to the magnetization state in state 1, magnetization becomes state 2 along the major loop. Referring to FIG. 19, when an applied magnetic field is applied to the magnetization state of state 2 in the plus direction, magnetization becomes state 3 (= state 1) along the major loop. Such magnetization change curves in states 1 to 3 are collectively referred to as an MH curve (major loop).

  Next, a method for determining the random demagnetization state will be described. Referring to FIG. 20, if the medium is in a random demagnetization state, the initial magnetization state is zero in magnetization, and therefore, the path of magnetization change follows a minor loop during VSM measurement. Also, it can be detected where the initial amount of magnetization is compared with the major loop.

  Thus, by confirming that the minor loop is followed and that the initial magnetization amount is 0, it can be confirmed that the medium is in a random demagnetization state.

  Next, a method for determining unidirectional demagnetization will be described. Referring to FIG. 21, when the medium is demagnetized in one direction, the path of magnetization change follows a major loop as shown in FIG. Thus, by confirming that the major loop is followed, it can be determined that the medium is demagnetized in one direction.

(4) Evaluation of vertical magnetic field application A DC magnetic field in a direction perpendicular to the surface of the medium was applied to each of the media 1 to 3, and the SN ratio after application was measured. The SN ratio was measured in the same manner as (2) above. Here, unidirectional demagnetization by application of a DC magnetic field will be described with reference to the drawings. FIG. 22 is a schematic view of an apparatus that has performed unidirectional demagnetization. As shown in FIG. 22, the application of the DC magnetic field was performed using opposing magnets composed of two pairs of permanent magnets. Of the two pairs of permanent magnets, a DC magnetic field was generated by placing the S pole of the other magnet opposite to the N pole of one magnet. A DC magnetic field was applied to the medium by passing the medium through a DC magnetic field between the two pairs of permanent magnets. The applied magnetic field strength was adjusted by changing the distance between the two pairs of magnets. In this way, by changing the strength of the applied magnetic field, the SN ratio of the medium was measured every time the magnetic field having the changed strength was applied. Here, the SN ratio of the evaluation signals of the media 1 to 3 before applying the horizontal magnetic field is 12 dB as determined in the above (2).

  The evaluation results are shown in FIGS. FIG. 10 is a diagram showing the SN ratio after a vertical magnetic field is applied to the medium 1. FIG. 11 is a diagram showing the SN ratio after a vertical magnetic field is applied to the medium 2. FIG. 12 is a diagram illustrating the SN ratio after applying a vertical magnetic field to the medium 3.

  10 to 12, the horizontal axis indicates the ratio between the applied vertical magnetic field strength Haz and the nucleation magnetic field Hn of the medium, and the vertical axis indicates the SN ratio of the medium after the vertical magnetic field is applied. As shown in FIG. 10 to FIG. 12, when a strong direct magnetic field is applied to the medium, that is, when a perpendicular magnetic field having a large Haz / Hn value is applied to the medium, the SN ratio decreases, and the media 1 to 3 are demagnetized. Is done.

  Here, when a DC vertical magnetic field is applied to the medium, the direction of the N pole and the S pole is perpendicular to the medium surface and is unidirectionally demagnetized in one direction. That is, the demagnetization performed here is one-way demagnetization.

  The object of the present invention is to perform random demagnetization. When the direct current magnetic field applied to the medium includes a magnetic field component perpendicular to the surface of the medium, the horizontal magnetic field attempts to demagnetize the medium randomly, and the vertical magnetic field Degaussing becomes unstable because it tries to demagnetize in the direction, eventually, depending on the ratio of horizontal magnetic field and vertical magnetic field among the magnetic field components applied to the medium, it becomes a demagnetized state where random demagnetization and unidirectional demagnetization are combined, eventually It has been found that random demagnetization is no longer true.

  As shown in FIGS. 10 to 12, in any medium 1 to 3 having different Hc and Hn, when Haz / Hn is 1.2 or less, the SN ratio of the evaluation signal before applying the vertical magnetic field is 12 dB to 1 dB. The fluctuation is within. If the SN ratio is reduced by 1 dB or less by applying a vertical magnetic field, the unidirectional magnetization component imparted to the medium is substantially small, so that random demagnetization by applying a horizontal magnetic field at the same time is not affected. Therefore, it is preferable to adjust the strength of the vertical magnetic field component so that the value of Haz / Hn is 1.2 or less.

  It is most preferable that the SN ratio decrease is 1 dB or less, but it does not have to be 1 dB or less. In other words, for random demagnetization, the decrease in the S / N ratio due to the application of the vertical magnetic field is preferably 3 dB or less, more preferably 2 dB or less, and most preferably 1 dB or less.

  Here, Haz / Hn represents the ratio of the applied magnetic field to the nucleation magnetic field Hn of the medium. By considering this Hn ratio, it is possible to easily know at what level the horizontal magnetic field strength Haz of the applied magnetic field becomes possible for one-way demagnetization. As a result, the same index can be considered when handling media with different Hn.

<Servo following performance evaluation>
Next, performance evaluation of servo following will be described. Using STW (servo track writer), servo signals (output type burst signals) were written to the above media 1 to 3, and servo PES (Position Error Signal) was evaluated.

  The servo part to which the servo signal is written using STW has a servo basic bit length of 60 nm at the innermost circumference of the medium, a layer sector number of 240, a track width of 60 nm, and a preamble (45 bits) / servo It consisted of mark (10bit) / SectorCode (8bit), CylinderCode (32bit) / Burst pattern.

  The servo mark part is “0000101011”, Sector is Binary, and Cylinder is Gray conversion. The Burst part used a general output type burst signal (ABCD burst) (40 bits).

  Examples 1 to 6 and Comparative Examples 1 to 3 use the medium 1, Examples 7 to 12 and Comparative Examples 4 to 6 use the medium 2, and Examples 13 to 18 and Comparative Examples 7 to 9 Medium 3 was used, and Comparative Example 10 used medium 2.

  In all the examples and comparative examples other than the comparative example 10, when the servo signal is recorded on the medium by the STW, no signal recording is performed in the inter-track portion between the tracks of the ABCD burst, and the inter-track portion is not recorded. The random demagnetization state initialized by the initialization method of the present invention was kept. As for Comparative Example 10, the inter-track portion has a fundamental frequency by the STW (the fundamental frequency is a frequency corresponding to a signal having the shortest wavelength among the bit signals measured in each track, as conventionally performed). AC was demagnetized by memorizing a high frequency signal twice as high as that of the non-magnetized state.

  Here, further description will be given with reference to FIGS. 13 and 14. FIG. 13 is an explanatory diagram for explaining the conventional bursts A and B in which a high-frequency signal is recorded between the tracks. FIG. 14 is an explanatory diagram for explaining a burst pattern recorded on a medium, in which a portion between tracks is in a random demagnetization state.

  As shown in FIG. 13, conventionally, a signal having a frequency twice the basic frequency smaller than the read width of the head is recorded in the portion between tracks. As a result, the head could not read the signal as positive or negative, and effectively had the same effect as the non-magnetized state. In the present invention, as shown in FIG. 14, the portion between tracks is in a state of being randomly demagnetized.

  The evaluation of the servo PES was performed using an evaluation device manufactured by Eymes (BitFinder). A head in VCM mode was mounted on the evaluation device, and PES was measured in a servo follow state.

  The standard deviation (σ) is calculated from the PES measurement value of each sector for 50 laps. If the 3σ value is less than 15% of the track pitch (TP), it is good (○), and it is acceptable if it is 15% or more and less than 25% ( (Triangle | delta), If it was 25% or more, it was judged that it was a defect (*).

  The evaluation results are shown in FIG. FIG. 15 is a diagram showing the results of servo following performance evaluation. As shown in FIG. 15, in any of the media 1 to 3, when the random demagnetization condition was Hah / Hc of 1.30 or more, the deviation amount was 24% or less of TP in the PES3σ value. Thus, a better result than the conventional example in which the high frequency signal was recorded in the portion between the tracks shown in Comparative Example 10 was shown.

  Further, when the condition of random demagnetization was Hah / Hc of 1.30 or more and Haz / Hn of 1.17 or less, the deviation amount was 15% or less of TP in the PES3σ value. As described above, the result was even better than the conventional example in which the high frequency signal was recorded in the portion between the tracks shown in Comparative Example 10.

  From the above, the servo signal recording medium is preferably in a state in which the portion between tracks is randomly demagnetized under the condition that Hah / Hc is 1.30 or more, Hah / Hc is 1.30 or more, and Haz / Hn is 1.17. It is more preferable that the state is randomly demagnetized under the following conditions. As a result, a servo recording medium having better servo following performance than the conventional servo signal recording medium can be obtained.

  Next, a servo signal recording medium (hereinafter, also referred to as a random demagnetization medium) in which a portion between tracks is randomly demagnetized, and a servo signal recording medium (hereinafter, a signal having a frequency twice the basic signal is recorded in a portion between tracks) , And also referred to as a conventional medium), the spectra obtained by Fourier transform were compared.

  FIG. 16 shows a spectrum obtained by Fourier transform. In the graph shown in FIG. 16, the vertical axis represents the amplitude, and the horizontal axis represents the ratio to the fundamental frequency indicating how many times the fundamental frequency is. A dotted line indicates a conventional medium, and a solid line indicates a random demagnetization medium.

  As shown in the figure, the solid line indicating the random demagnetization medium is at a lower position as a whole than the solid line indicating the conventional medium, which is generally less noise in the random demagnetization medium than in the conventional medium. It is shown that. In addition, since the dotted line indicating the conventional medium records a signal having a frequency twice that of the basic signal, the horizontal axis has a peak at a position of 2.

  From the above, it can be said that the random demagnetization medium is superior because the noise is lower than the conventional AC demagnetization medium.

  DESCRIPTION OF SYMBOLS 103 ... Medium, 110 ... Electromagnet, 112 ... Core, 114 ... Coil, 116 ... Magnetic field, 118 ... Current supply means, 120 ... Electromagnet, 122 ... Core, 124 ... Coil, 126 ... Magnetic field, 128 ... Current supply means, 130 ... Medium, 200 ... Initialization device, 210 ... Permanent magnet, 216 ... Magnetic field, 220 ... Permanent magnet, 300 ... Initialization device, 310 ... Electromagnet, 312 ... Core, 314 ... Coil, 318 ... Current supply means, 320 ... Electromagnet, 322 ... Core, 400 ... Initialization device, 410 ... Permanent magnet, 420 ... Permanent magnet

Claims (11)

An initialization method of a perpendicular magnetic recording medium for initializing a perpendicular magnetic recording medium having a coercive force of Hc and a nucleation magnetic field of Hn,
An arrangement step of arranging the perpendicular magnetic recording medium at a predetermined position;
A magnetic field applying step in which a magnetic field applying unit having an electromagnet or a permanent magnet applies a DC magnetic field Ha to the perpendicular magnetic recording medium;
With
In the magnetic field application step,
Among the components of the DC magnetic field Ha, when the horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium is Hah, the vertical magnetic field component that is a vertical component is Haz,
Haz / Hn ≦ 1.17 and Hah / Hc ≧ 1.3
An initialization method for a perpendicular magnetic recording medium in which the DC magnetic field Ha is applied to the perpendicular magnetic recording medium. In the arranging step, the perpendicular magnetic recording medium is DC-directed to the perpendicular magnetic recording medium, one of the two faces of which faces the magnetic field applying means and the other face has an electromagnet or a permanent magnet. Arranged so as to face the second magnetic field applying means for applying the magnetic field Ha2,
In the magnetic field application step,
The second magnetic field applying means comprises:
Of the components of the DC magnetic field Ha2, the horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium is Hah2, and the vertical magnetic field component that is a vertical component is Haz2.
Haz2 / Hn2 ≦ 1.17 and Hah2 / Hc2 ≧ 1.3
And
In the perpendicular magnetic recording medium, the Ha2 is applied to the perpendicular magnetic recording medium so that the Hah2 is in the same direction as the Hah.
The method for initializing a perpendicular magnetic recording medium according to claim 1. An initialization method of a perpendicular magnetic recording medium for initializing a perpendicular magnetic recording medium having a coercive force of Hc and a nucleation magnetic field of Hn,
An arrangement step of arranging the perpendicular magnetic recording medium at a predetermined position;
A magnetic field applying step in which a magnetic field applying unit having an electromagnet or a permanent magnet applies a DC magnetic field Ha to the perpendicular magnetic recording medium;
With
In the magnetic field application step,
Among the components of the DC magnetic field Ha, when the horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium is Hah, the vertical magnetic field component that is a vertical component is Haz,
Haz / Hn ≦ 1.2 and Hah / Hc ≧ 1.5
An initialization method for a perpendicular magnetic recording medium in which the DC magnetic field Ha is applied to the perpendicular magnetic recording medium. In the arranging step, the perpendicular magnetic recording medium is DC-directed to the perpendicular magnetic recording medium, one of the two faces of which faces the magnetic field applying means and the other face has an electromagnet or a permanent magnet. Arranged so as to face the second magnetic field applying means for applying the magnetic field Ha2,
In the magnetic field application step,
The second magnetic field applying means comprises:
Of the components of the DC magnetic field Ha2, the horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium is Hah2, and the vertical magnetic field component that is a vertical component is Haz2.
Haz2 / Hn ≦ 1.2 and Hah2 / Hc ≧ 1.5
And
In the perpendicular magnetic recording medium, the Ha2 is applied to the perpendicular magnetic recording medium so that the Hah2 is in the same direction as the Hah.
The method for initializing a perpendicular magnetic recording medium according to claim 3. An apparatus for initializing a perpendicular magnetic recording medium for initializing a perpendicular magnetic recording medium having a coercive force of Hc and a nucleation magnetic field of Hn,
Comprising a magnetic field applying means for applying a DC magnetic field Ha to the perpendicular magnetic recording medium,
The magnetic field applying means includes
Arranged to face one surface of the perpendicular recording medium,
Among the components of the DC magnetic field Ha, when the horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium is Hah, the vertical magnetic field component that is a vertical component is Haz,
Haz / Hn ≦ 1.17 and Hah / Hc ≧ 1.3
So that
The magnitude of the DC magnetic field Ha,
A relative position of the magnetic field applying means with respect to the perpendicular magnetic recording medium;
An initialization apparatus for a perpendicular magnetic recording medium in which adjustment is made. A second magnetic field applying means for applying a DC magnetic field Ha2 to the perpendicular recording medium;
The second magnetic field applying unit is disposed to face a surface of the perpendicular magnetic recording medium on which the magnetic field applying unit is not disposed,
Of the components of the DC magnetic field Ha2, the horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium is Hah2, and the vertical magnetic field component that is a vertical component is Haz2.
Haz2 / Hn ≦ 1.17 and Hah2 / Hc ≧ 1.3
And so that Ha2 and Ha are in the same direction in the perpendicular magnetic recording medium,
The magnitude of the DC magnetic field Ha2,
A relative position of the second magnetic field applying means with respect to the perpendicular magnetic recording medium;
The initialization apparatus for a perpendicular magnetic recording medium according to claim 5, wherein the adjustment is adjusted. An apparatus for initializing a perpendicular magnetic recording medium for initializing a perpendicular magnetic recording medium having a coercive force of Hc and a nucleation magnetic field of Hn,
Comprising a magnetic field applying means for applying a DC magnetic field Ha to the perpendicular magnetic recording medium,
The magnetic field applying means includes
Arranged to face one surface of the perpendicular recording medium,
Among the components of the DC magnetic field Ha, when the horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium is Hah, the vertical magnetic field component that is a vertical component is Haz,
Haz / Hn ≦ 1.2 and Hah / Hc ≧ 1.5
So that
The magnitude of the DC magnetic field Ha,
A relative position of the magnetic field applying means with respect to the perpendicular magnetic recording medium;
An initialization apparatus for a perpendicular magnetic recording medium in which adjustment is made. A second magnetic field applying means for applying a DC magnetic field Ha2 to the perpendicular recording medium;
The second magnetic field applying unit is disposed to face a surface of the perpendicular magnetic recording medium on which the magnetic field applying unit is not disposed,
Of the components of the DC magnetic field Ha2, the horizontal magnetic field component that is a component parallel to the surface of the perpendicular magnetic recording medium is Hah2, and the vertical magnetic field component that is a vertical component is Haz2.
Haz2 / Hn ≦ 1.2 and Hah2 / Hc ≧ 1.5
And so that Ha2 and Ha are in the same direction in the perpendicular magnetic recording medium,
The magnitude of the DC magnetic field Ha2,
A relative position of the second magnetic field applying means with respect to the perpendicular magnetic recording medium;
The initialization device for a perpendicular magnetic recording medium according to claim 7, wherein is adjusted.   The perpendicular magnetic recording medium initialization apparatus according to claim 5 or 7, wherein an interval between the south pole and the north pole of the magnetic field applying means is equal to or larger than the diameter of the perpendicular magnetic recording medium.   The distance between the south pole and the north pole of the magnetic field applying means is not less than the diameter of the perpendicular magnetic recording medium, and the distance between the south pole and the north pole of the second magnetic field applying means is the perpendicular magnetic recording. The perpendicular magnetic recording medium initialization apparatus according to claim 6 or 8, wherein the initialization apparatus has a diameter equal to or larger than the diameter of the medium. A perpendicular magnetic recording medium that has been initialized by the method for initializing a perpendicular magnetic recording medium according to claim 1 or 2 and then written with a servo signal,
A perpendicular magnetic recording medium in which an initialized random demagnetization state is maintained between the tracks in the burst portion.

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