JP2009205730A - Perpendicular magnetic recording medium and magnetic recording/playback device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve recording sensitivity by achieving high density. <P>SOLUTION: The perpendicular magnetic recording medium 1 is constructed by sequentially stacking a soft magnetic backing layer 3, a base layer 5, a recording layer 6, and a protective layer 9 on a substrate 2. The recording layer 6 includes a magnetic recording layer 7 formed on the base layer 5 side and comprising a granular crystal structure containing at least Co and Pt, and a recording auxiliary layer 8 formed on the protective layer 9 side, having coercive force smaller than that of the magnetic recording layer 7 and comprising a granular crystal structure containing at least Fe and Pt. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a perpendicular magnetic recording medium and a magnetic recording / reproducing apparatus, and is suitable for application to, for example, a large-capacity magnetic recording / reproducing apparatus.

  Conventionally, as a magnetic recording medium such as a perpendicular magnetic recording medium, various kinds of information such as various contents such as music contents and video contents, or various data for a computer are recorded on the perpendicular magnetic recording medium. Yes. In particular, in recent years, the amount of information has increased due to higher definition of video and higher sound quality of music, and an increase in the number of contents recorded on one magnetic recording medium is required. Large capacity is required.

  In a perpendicular magnetic recording medium, since the magnetic pole is changed in the direction perpendicular to the substrate, the demagnetizing field is reduced as the recording density is improved, and the recording state can be stabilized, and the area per magnetic pole is reduced. High density is achieved.

  In this perpendicular magnetic recording medium, it is desired to reduce the crystal grain size of the recording layer in order to further increase the density. However, it is known that as the crystal particle diameter becomes smaller, thermal fluctuations that cause the recording state to become unstable due to changes in the magnetization direction of the crystal particles due to thermal energy.

  In order to prevent this thermal fluctuation, it is necessary to increase the anisotropy of the crystal grains. However, as the anisotropy increases, the coercive force as the recording layer increases, and the recording sensitivity decreases. End up. Further, from the viewpoint of material, it is not possible to expect a great improvement in the recording capability of the recording head. When the anisotropy of crystal grains is increased, it is necessary to improve the recording sensitivity of the recording layer.

  Therefore, as a recording layer, a recording auxiliary layer having a low coercive force provided on the surface layer side and a magnetic recording layer having a relatively large coercive force are provided, and after changing the magnetic pole of the recording auxiliary layer where the magnetic pole changes relatively easily, Proposed a perpendicular magnetic recording medium designed to reduce the apparent coercivity of the recording layer as a whole and improve recording sensitivity by changing the magnetic pole of the magnetic recording layer using the magnetic force of the auxiliary recording layer (For example, refer to Patent Document 1).

Further, as a recording auxiliary layer and a magnetic recording layer, a CoCrPt—Sio ₂ film having a different composition is laminated as a granular film, thereby improving the thermal stability and SNR (Signal to Noise Ratio). Has been proposed (see, for example, Patent Document 2).
JP 2006-48900 A JP 2006-155861 A

  By the way, in the perpendicular magnetic recording medium described in Patent Document 1, since the magnetic recording layer is not formed as a granular film, the separation between crystal grains is weak and the anisotropy cannot be increased, and sufficient density increase is achieved. Have difficulty.

In the perpendicular magnetic recording medium described in Patent Document 2, although the composition is different, both the recording auxiliary layer and the magnetic recording layer have a CoCrPt-Sio ₂ film laminated thereon, so that the crystal grains between the recording auxiliary layer and the magnetic recording layer Cannot be separated sufficiently. As a result, in this perpendicular magnetic recording medium, since the interaction between the recording auxiliary layer and the magnetic recording layer becomes large and it is difficult to change the magnetic pole of the recording auxiliary layer with a small magnetic force, the coercive force can be greatly reduced. Therefore, the recording sensitivity cannot be improved sufficiently.

  That is, the perpendicular magnetic recording medium has a problem that it is very difficult to improve the recording sensitivity after increasing the density.

  The present invention has been made in consideration of the above points, and intends to propose a perpendicular magnetic recording medium capable of improving the recording sensitivity after increasing the density and a magnetic recording / reproducing apparatus using the perpendicular magnetic recording medium. It is.

  In order to solve such a problem, in the present invention, a perpendicular magnetic recording medium in which at least a soft magnetic backing layer, an underlayer, a recording layer, and a protective layer are sequentially laminated on a substrate, wherein the recording layer comprises: A magnetic recording layer having a granular crystal structure containing at least Co and Pt, formed on the underlayer side, and a coercive force smaller than that of the magnetic recording layer, formed on the protective layer side, and containing at least Fe and Pt A recording auxiliary layer having a granular crystal structure was provided.

  As a result, since both the magnetic recording layer and the auxiliary recording layer have a granular crystal structure, the crystal grains in the layer can be sufficiently separated and the anisotropy can be increased, so that information can be recorded at a high density. In addition, since the magnetic recording layer and the recording auxiliary layer contain different elements, the magnetic recording layer and the recording auxiliary layer can be sufficiently separated from each other and the magnetic pole of the recording auxiliary layer can be changed with a small magnetic force. In addition, the coercive force of the recording auxiliary layer as a whole can be reduced.

  In the present invention, at least a soft magnetic backing layer, an underlayer, a recording layer, and a perpendicular magnetic recording medium in which a protective layer is sequentially laminated on the substrate, and information is recorded on the perpendicular magnetic recording medium, And a magnetic head for reading information recorded on the perpendicular magnetic recording medium and a drive unit for driving the magnetic head, and the recording layer is formed on the underlayer side and has a granular crystal structure containing at least Co and Pt. A magnetic recording layer and a recording auxiliary layer formed on the protective layer side and having a coercive force smaller than that of the magnetic recording layer and having a granular crystal structure containing at least Fe and Pt are provided.

  As a result, since both the magnetic recording layer and the auxiliary recording layer have a granular crystal structure, the crystal grains in the layer can be sufficiently separated and the anisotropy can be increased, so that information can be recorded at a high density. In addition, since the magnetic recording layer and the recording auxiliary layer contain different elements, the magnetic recording layer and the recording auxiliary layer can be sufficiently separated from each other and the magnetic pole of the recording auxiliary layer can be changed with a small magnetic force. In addition, the coercive force of the recording auxiliary layer as a whole can be reduced.

  According to the present invention, since both the magnetic recording layer and the recording auxiliary layer have a granular crystal structure, the crystal grains in the layer can be sufficiently separated to increase the anisotropy, so that information is recorded at a high density. In addition, since the magnetic recording layer and the auxiliary recording layer contain different elements, the magnetic particles in the auxiliary recording layer can be changed with a small magnetic force by sufficiently separating crystal grains between the magnetic recording layer and the auxiliary recording layer. Perpendicular magnetic recording medium capable of reducing coercive force as a whole of magnetic recording layer and auxiliary recording layer and thus improving recording sensitivity after increasing the density and magnetic recording / reproducing apparatus using the perpendicular magnetic recording medium Can be realized.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of Perpendicular Magnetic Recording Medium In FIG. 1, reference numeral 1 denotes a cross section of the perpendicular magnetic recording medium in the present embodiment. In this perpendicular magnetic recording medium 1, a soft magnetic backing layer 3, a seed layer 4, an underlayer 5, a magnetic recording layer 7 and a recording auxiliary layer 8 as a recording layer 6, and a protective layer 9 are sequentially laminated on a substrate 2. It is constituted by.

  The substrate 2 is a disk-shaped nonmagnetic substrate having a flat surface, and is composed of, for example, a plastic substrate, a crystallized glass substrate, a tempered glass substrate, a Si substrate, an aluminum alloy substrate, a ceramic substrate, or the like.

  The soft magnetic backing layer 3 has a film thickness of, for example, 20 [nm] to 2 [μm], and is selected from Fe, Co, Ni, Al, Si, Ta, Ti, Zr, Hf, V, Nb, C, and B Formed of a soft magnetic material containing at least one element. Specifically, the soft magnetic backing layer 3 is made of FeSi, FeAlSi, FeTaC, CoFeB, CoZrNb, NiFeNb, or the like.

  The seed layer 4 has a thickness of, for example, 1 [nm] to 10 [nm] (preferably 1 [nm] to 5 [nm]), and is a group consisting of Ta, Ti, Mo, W, Re, Hf, and Mg. Of these, at least one amorphous nonmagnetic material is used. Since the seed layer 4 is amorphous, the crystal orientation of the underlayer 5 can be improved without affecting the crystal orientation of the underlayer 5 formed on the seed layer 4. .

  The underlayer 5 is made of a nonmagnetic material having an hcp (hexagonal close-packed) crystal structure. For example, any one of a group consisting of Ru, Pd, Pt, Ta, and a Ru alloy is selected and used. preferable. Since the underlayer 5 has an hcp crystal structure, the magnetic recording layer 7 having an hcp crystal structure formed on the underlayer 5 is epitaxially grown to disperse the crystal orientation of the magnetic recording layer 7. It is made to improve the sex.

  The magnetic recording layer 7 is a CoPt granular film having an hcp crystal structure, and has a granular crystal structure composed of magnetic particles mainly made of a ferromagnetic material and crystal grain boundaries mainly made of a nonmagnetic material. is doing. Since the magnetic particles are physically separated from the adjacent magnetic particles by the crystal grain boundary portion, the magnetic interaction between the magnetic particles can be reduced and the anisotropy can be improved.

This magnetic particle contains at least Co and Pt and exhibits ferromagnetism. The magnetic particles may contain elements such as Cr, Ta, and Ru as appropriate. The crystal grain boundary is a compound of any one element selected from Si, Al, Ta, Zr, Y, Ti, and Mg and any one element selected from O, N, and C. made, and for example _{Si0 2, Al 2 O 3,} Ta 2 O 5, an oxide such as _{TiO 2, Si 3 N 4,} AlN, TaN, ZrN, nitrides such as TiN, SiC, TaC, ZrC, TiC, etc. Made of carbide.

Specifically, the magnetic recording layer 7 is preferably made of CoCrPt—TiO ₂ or CoCrPt—SiO ₂ and has a thickness of 5 to 50 [nm], for example. The content ratio of Co, Cr, and Pt, and the content ratio of CoCrPt and TiO ₂ or SiO ₂ can be changed as appropriate.

  The recording auxiliary layer 8 is an FePt-based granular film having an fcc (face centered cubic lattice) crystal structure, and is composed of magnetic particles mainly made of a ferromagnetic material and crystal grain boundaries mainly made of a nonmagnetic material. It has a granular crystal structure.

  This magnetic particle contains at least Fe and Pt and exhibits ferromagnetism. Further, the magnetic particles may appropriately contain elements such as Cr, Ta and Ru. The crystal grain boundary part is made of the same compound as the crystal grain boundary part in the magnetic recording layer 7.

Specifically, the recording auxiliary layer 8 is preferably made of FeCrPt—TiO ₂ or FeCrPt—SiO ₂ . The content ratio of Co, Cr, and Pt, and the content ratio of FeCrPt and oxide can be changed as appropriate.

  The recording auxiliary layer 8 has a thickness of 1 to 5 [nm], preferably 1.5 to 4 [nm]. The auxiliary recording layer 8 is made of a material having a lower coercive force than that of the magnetic recording layer 7. The recording auxiliary layer 8 changes the magnetic pole with a relatively small magnetic force, and also assists in changing the magnetic pole of the magnetic recording layer 7 with the magnetic force generated at this time, whereby the recording layer 6 (the magnetic recording layer 7 and the recording auxiliary layer). The overall coercive force of 8) can be reduced.

  Further, since the recording auxiliary layer 8 contains an element Fe different from that of the magnetic recording layer 7, the interaction between the crystal grains of the recording auxiliary layer 8 and the crystal grains of the magnetic recording layer 7 can be sufficiently weakened. The coercivity of the recording layer 6 as a whole can be effectively reduced by changing the magnetic pole of the recording auxiliary layer 8 with a small magnetic force.

  The protective film 9 has a film thickness of, for example, 0.5 [nm] to 15 [nm], and is formed of amorphous carbon, hydrogenated carbon, carbon nitride, aluminum oxide, or the like. A lubricating layer made of perfluoropolyether or the like may be provided on the protective film 9.

  This perpendicular magnetic recording medium 1 uses a sputtering target on which a soft magnetic backing layer 3, a seed layer 4, an underlayer 5, a magnetic recording layer 7, and a recording auxiliary layer 8 are made of the above-described materials on a substrate 2, and DC It is formed by sequentially forming a film by magnetron sputtering, RF magnetron sputtering, DC bipolar sputtering, RF bipolar sputtering, or the like.

As the sputtering apparatus, it is preferable to use an ultra-vacuum sputtering apparatus capable of exhausting to 10 ⁻⁷ Pa. Conditions suitable for each material are set as sputtering conditions and are not particularly limited. For example, a film can be formed at a predetermined pressure in an Ar gas atmosphere and heated.

  The protective film 9 is formed on the auxiliary recording layer 8 by using, for example, sputtering, CVD (Chemical Vapor Deposition), FCA (Filtered Cathodic Arc), or the like. When a lubricating layer is provided on the protective film 9, a lubricant is applied on the protective film 9 by a spin coat method, a pulling method, or the like.

(2) Configuration of Magnetic Recording / Reproducing Device and Recording Head Unit As shown in FIG. 2, the magnetic recording / reproducing device 1 is controlled by the control unit 21 as a whole. The control unit 21 is mainly configured by a CPU (Central Processing Unit) (not shown), reads various programs such as a basic program and an information recording program from a ROM (Read Only Memory) (not shown), and stores them in a RAM (Random) (not shown). Various processes such as an information recording process and an information reproduction process are executed by developing the data in an “Access Memory”.

  For example, when the control unit 11 receives an information recording command, recording information, and recording address information from an external device (not shown), the control unit 11 supplies the driving command and recording address information to the driving control unit 12 and sends the recording information to the signal processing unit 13. Supply. Incidentally, the recording address information is information indicating the address of the recording bit which is one unit in the recording layer 6 of the perpendicular magnetic recording medium 1 where the recording information is recorded.

  The drive control unit 12 rotates the perpendicular magnetic recording medium 1 at a predetermined rotation speed by driving and controlling the spindle motor 14 in accordance with a drive command, and by driving and controlling the drive unit 15 including an arm and a rotary actuator. The magnetic head 20 is moved to a position corresponding to the recording address information in the perpendicular magnetic recording medium 1.

  The signal processing unit 13 generates a recording signal by performing various signal processing such as predetermined encoding processing and modulation processing on the supplied recording information, and supplies this to the magnetic head 20.

  The magnetic head 20 applies a magnetic force to the recording bit indicated by the recording address information in the recording layer 6 of the perpendicular magnetic recording medium 1 in accordance with the recording signal, thereby changing the magnetic pole of the recording bit in accordance with the recording signal. 6 records information.

  When the control unit 11 receives an information reproduction command and reproduction address information indicating the address of the recorded information from, for example, an external device (not shown), the control unit 11 supplies the drive command and the reproduction address information to the drive control unit 12. The reproduction processing command is supplied to the signal processing unit 13.

  As in the case of recording information, the drive control unit 12 controls the spindle motor 14 to rotate the perpendicular magnetic recording medium 1 at a predetermined rotational speed, and controls the drive unit 15 to drive the magnetic head 20. Is moved to a position corresponding to the reproduction address information.

  The magnetic head 20 detects the magnetic field of the recording bit indicated by the reproduction address information in the recording layer 6 of the perpendicular magnetic recording medium 1 based on the control of the drive control unit 12 and supplies this to the signal processing unit 13 as a reproduction signal. It is made like that.

  As shown in FIG. 3, the magnetic head 20 has a single magnetic pole type magnetic recording head 21 used for information recording processing and a GMR (Giant Magnetic Resistance) element 25 used for information reproducing processing. The magnetic head 20 is driven by the drive unit 15 (FIG. 2) to perform information recording processing in a state where the single magnetic pole type magnetic recording head 21 or the GMR element 25 is arranged on a desired recording bit in the magnetic recording medium 1. Alternatively, the information reproduction process is executed.

  During the information recording process, the single-pole magnetic recording head 21 generates a magnetic force between the tip of the main pole 22 and the tip of the auxiliary pole 23 by passing a current through a coil included therein. At this time, the soft magnetic backing layer 3 induces a magnetic force in a direction perpendicular to the magnetic recording medium 1 and suppresses the magnetic force from spreading to adjacent recording bits.

  As a result, the soft magnetic backing layer 3 forms a closed magnetic circuit that concentrates the magnetic force generated from the main magnetic pole 22 on the recording bit, for example, and passes the magnetic force through the soft magnetic backing layer 3 itself to return to the auxiliary pole 23. A part of the magnetic head function is shared. This magnetic force is shown in the figure as a magnetic line 24.

  The single magnetic pole type magnetic recording head 21 changes the magnetic force direction according to the direction of the current flowing in the coil, thereby changing the magnetic pole of the recording bit in one direction perpendicular to the substrate in accordance with the information to be recorded. 6 is configured to record information.

  At this time, since the apparent coercive force is small and the recording sensitivity is improved as described above, the recording layer 6 can appropriately change the magnetic pole of the recording bit according to the recorded information.

  The GMR element 25 changes the resistance value in proportion to the strength of the magnetic field. During the information reproducing process, the GMR element 25 changes the resistance value according to the information recorded in the recording bit. The GMR element 25 is sandwiched between the GMR magnetic shields 26 that block the magnetic force so as not to be affected as much as possible by the magnetic field other than the recording bit.

  The magnetic head 20 detects a change in the resistance value of the GMR element 25 by a resistance value detection unit (not shown), and supplies this to the signal processing unit 13 as a reproduction signal.

  The signal processing unit 13 (FIG. 2) generates reproduction information by performing various signal processing such as predetermined demodulation processing and decoding processing on the supplied reproduction signal, and supplies this reproduction information to the control unit 11. To do. In response to this, the control unit 11 sends the reproduction information to an external device (not shown).

  At this time, since the recording layer 6 has the magnetic pole of the recording bit appropriately changed according to the recorded information, the noise of the reproduction signal can be reduced and the SNR (Signal to Noise Ratio) of the reproduction signal is improved. It is made to be able to let you.

  Thus, the magnetic recording / reproducing apparatus 10 records information on the recording bits in the recording layer 6 of the perpendicular magnetic recording medium 1 by reproducing the information from the recording bits by controlling the magnetic head 20 by the control unit 11. It is made like that.

(3) Examples Next, examples will be described.

(3-1) Example 1
After placing the glass substrate 2 in the vacuum chamber of the sputtering apparatus and evacuating the chamber of the sputtering apparatus to a predetermined pressure, the soft magnetic backing layer 3 in an argon atmosphere without heating the substrate 2; A seed layer 4, an underlayer 5, a magnetic recording layer 7, a recording auxiliary layer 8, and a protective film 9 were sequentially formed to produce a sample as the perpendicular magnetic recording medium 1.

That is, after a 50 [nm] CoZrNb film was formed on the substrate 2 as the soft magnetic backing layer 3, a 2 [nm] Ta layer was formed as the seed layer 4. Further, a 20 [nm] Ru film was formed as the underlayer 5, and a 10 [nm] CoCrPt—TiO ₂ film was formed as the magnetic recording layer 7. Further, an FeCrPt—Tio ₂ film was formed as the recording auxiliary layer 8 on the magnetic recording layer 7, and finally a carbon film of 3 [nm] was formed as the protective film 9.

  Details of the sputtering conditions when the soft magnetic backing layer 3, the seed layer 4, the underlayer 5, the magnetic recording layer 7, the recording auxiliary layer 8, and the protective film 9 are formed are shown below.

  The film thickness in each layer formed was calculated from the film formation rate under the above sputtering conditions. The film forming speed and film thickness are shown below. In addition, when the actual film thickness of each layer was measured with a film thickness meter that measured the film thickness by the light interference color measurement method, it was confirmed that the film of each layer was formed within an error range of ± 5%. .

  As the perpendicular magnetic recording medium 1, a plurality of samples in which the thickness of the recording auxiliary layer 8 was changed were manufactured in order to confirm the characteristics relating to the thickness of the recording auxiliary layer 8. The recording auxiliary layer 8 has a thickness of 1, 1.5, 2, 2.5, 3, 4 or 5 [nm], respectively. 1-No. It was set to 7. For comparison, a comparative sample without the magnetic recording layer 7 was also prepared. It was set to 11.

  And each sample No. 1-No. 7 and comparative sample no. 11 is recorded with measurement information consisting of repetition of “1” and “0” at a linear recording density of 150 [kfci] using a spin stand, and the measurement information is reproduced, and the CNR in the reproduction signal is reproduced. (Career to Noise Ratio) was measured. Table 3 shows a list of measured CNRs. The CNR indirectly represents the SNR in the reproduction signal at the time of information reproduction processing, and the SNR increases as the CNR increases, and the SNR decreases as the CNR decreases.

  As can be seen from Table 3, the comparative sample No. in which the recording auxiliary layer 8 is not provided. Compared with sample No. 11, sample No. 1-No. 7 confirmed that the CNR was improved. This is sample no. 1-No. 7, the recording auxiliary layer 8 having a low coercive force is provided, so that the recording auxiliary layer 8 acts as a capping layer.

  That is, sample no. 1-No. 7, the magnetic pole of the magnetic recording layer 7 can be easily changed by the magnetic force from the recording auxiliary layer 8 by quickly changing the magnetic pole according to the magnetic force of the recording bit of the recording auxiliary layer 8 being relatively small. . As a result, sample no. 1-No. 7 can reduce the apparent coercive force of the recording layer 6 as a whole composed of the recording auxiliary layer 8 and the magnetic recording layer 7 to improve the recording sensitivity, and the CNR is improved accordingly.

  Sample No. 1 to NO. It was confirmed that as the thickness of the recording auxiliary layer 8 increased to 4 (1 [nm] → 2.5 [nm]), the CNR improved and the effect of the recording auxiliary layer 8 increased. On the other hand, the sample No. 4 as a boundary, sample no. 5-No. It was confirmed that the CNR was decreased when the thickness of the recording auxiliary layer 8 was further increased to 7.

  This is presumably because the coercive force of the recording layer 6 as a whole is too low, which changes the magnetic pole of the recording bit adjacent to the recording bit to be recorded, and generates noise.

  That is, if the film thickness of the auxiliary recording layer 8 is within the range of 1 [nm] to 5 [nm], the CNR can be improved, and further within the range of 1.5 [nm] to 4 [nm]. If so, it can be said that the CNR can be made particularly good.

From the above, it was confirmed that the recording sensitivity can be improved and the quality of the reproduction signal can be improved by providing the FeCrPt—TiO ₂ film as the recording auxiliary layer 8.

(3-2) Example 2
First, a CoCrPt—Tio ₂ film having a reduced coercive force by increasing the Cr content over the CoCrPt—Tio ₂ used in the magnetic recording layer 7 is formed as the recording auxiliary layer 8, and a comparative sample and did.

In this comparative sample, a CoCrPt—Tio ₂ film was formed under the same conditions as the recording auxiliary layer 8 in Example 1, and the film thickness of the recording auxiliary layer 8 was changed. 15, no. 16, no. It was set to 17.

  In Example 2, the sample No. used in Example 1 was changed. 1, no. 4 and no. 7 and comparative sample No. 11, no. 15, no. 16 and no. For No. 17, the coercivity of the recording layer 6 as a whole consisting of the auxiliary recording layer 8 and the magnetic recording layer 7 was measured using a Kerr measuring device.

  In FIG. The measurement result about 11 is represented as a graph. In the graph, the value of the magnetic field when the Kerr rotation angle becomes zero is the coercive force.

  Table 4 shows the coercivity results measured for each sample.

As can be seen from Table 4, sample No. 1 provided with a FeCrPt—TiO ₂ film as the recording auxiliary layer 8 was obtained. 1, no. 4 and no. 7 is a comparative sample No. 7 in which no recording auxiliary layer 8 is provided. It was confirmed that the coercive force as the recording layer 6 was lower than that of the recording layer 6. In particular, Sample No. in which the film thickness of the recording auxiliary layer 8 is 1.5 [nm] or more. 4 and no. In No. 7, the decrease in coercive force was significant.

On the other hand, a comparative sample No. 1 provided with a CoCrPt—Tio ₂ film as the recording auxiliary layer 8 was used. 15 and no. 16 is a comparative sample no. It was confirmed that the coercive force as the recording layer 6 was increased as compared with 11.

  In addition, the comparative sample No. 1 in which the film thickness of the recording auxiliary layer 8 was increased to 5 [nm]. 17, comparative sample No. Compared to 11, the holding power as the recording layer 6 was reduced, but the reduction effect was slight.

That is, even when the recording auxiliary increase 8 has the same granular crystal structure, when the CoCrPt—Tio ₂ film containing the same element as the magnetic recording layer 7 is provided, the crystal between the recording auxiliary layer 8 and the magnetic recording layer 7 is provided. Since the particles could not be sufficiently separated and it was difficult for the recording auxiliary layer 8 to change the magnetic pole alone, the effect of reducing the coercive force as with the FeCrPt—TiO ₂ film was not observed.

From the above, it was confirmed that the apparent coercivity of the recording layer 6 as a whole can be actually reduced by providing the FeCrPt—TiO ₂ film as the recording auxiliary layer 8.

(3-3) Example 3
In Example 3, a 20 [nm] FeCrPt—TiO ₂ film was formed as the recording auxiliary layer 8 and X-ray diffraction measurement was performed.

In FIG. 5, the peak PK <b> 1 is due to the (111) plane of the FeCrPt—TiO ₂ film as the recording auxiliary layer 8. The peak PK2 is due to the (002) plane of the CoCrPt—Tio ₂ film as the magnetic recording layer 7.

As a result of measuring the orientation dispersibility with respect to the peak PK1, Δθ50, which is a half-value width, was 4.1 [deg] equivalent to the values of the magnetic recording layer 7 and the underlayer 5. From this, it can be said that the orientation dispersibility of the FeCrPt—TiO ₂ film is very good.

That is, FeCrPt-TiO ₂ film is a fcc crystal structure is grown orderly CoCrPt-Tio ₂ film which was the hcp crystal structure, found that the orientation of the FeCrPt-TiO ₂ film does not adversely affect the reproduction signal SNR It was. This can be said to be a result of supporting that the CNR of the reproduction signal in Example 1 was good.

From the above, a CoPt system is used as the magnetic recording layer 7 and an FePt system is used as the recording auxiliary layer 8, and the elements contained are different from each other but formed on the CoCrPt-Tio ₂ film as the magnetic recording layer 7. It was confirmed that the orientation dispersibility of the FeCrPt—TiO ₂ film as the recording auxiliary layer 8 is good and noise in the reproduction signal SNR can be reduced.

(4) Operation and Effect In the above configuration, the perpendicular magnetic recording medium 1 is formed by sequentially laminating at least a soft magnetic backing layer 3, an underlayer 5, a recording layer 6, and a protective layer 9 on a substrate 2. . The recording layer 6 is formed on the underlayer 5 side, and is formed on the magnetic recording layer 7 having a granular crystal structure containing at least Co and Pt, and on the protective layer 9 side, and has a smaller coercive force than the magnetic recording layer 7. And a recording auxiliary layer 8 having a granular crystal structure containing at least Fe and Pt.

  As a result, the perpendicular magnetic recording medium 1 can form both the magnetic recording layer 7 and the recording auxiliary layer 8 with a granular crystal structure, so that the crystal grains can be sufficiently separated from each other to increase the anisotropy. Recording at a recording density is possible.

  Further, since the perpendicular magnetic recording medium 1 contains different elements in the magnetic recording layer 7 and the recording auxiliary layer 8, crystal grains between the magnetic recording layer 7 and the recording auxiliary layer 8 can be sufficiently separated. For this reason, the perpendicular magnetic recording medium 1 has a relatively small influence of the magnetic force from the magnetic recording layer 7 in the recording auxiliary layer 8 and can change the magnetic pole of the recording bit in the recording auxiliary layer 8 with a small magnetic force. The magnetic pole of the recording bit in the magnetic recording layer 7 can be changed using the magnetic force of 8. As a result, the perpendicular magnetic recording medium 1 can remarkably reduce the apparent coercive force as the recording layer 6 as a whole, and can improve the recording sensitivity.

  Further, in the perpendicular magnetic recording medium 1, the magnetic recording layer 7 has a granular crystal structure containing at least Co and Pt, and the recording auxiliary layer 8 has a granular crystal structure containing at least Fe and Pt. Here, the auxiliary recording layer 8 has an fcc crystal structure and is different in crystal structure from the magnetic recording layer 7 having an hcp crystal structure. However, it has been experimentally confirmed that the FePt-based recording auxiliary layer 8 grows cleanly on the CoPt-based magnetic recording layer 7 and has good orientation dispersibility.

  As a result, since the perpendicular magnetic recording medium 1 does not have a large disturbance in crystal grains, it is possible to reduce noise in the reproduction signal and improve SNR.

  In addition, the perpendicular magnetic recording medium 1 can have Fe having a bcc (body-centered cubic lattice) crystal structure in the fcc crystal structure by including Fe and Pt in the recording auxiliary layer 8, and the hcp crystal structure Therefore, the orientation dispersibility of the auxiliary recording layer 8 on the magnetic recording layer 7 can be improved.

  According to the above configuration, the perpendicular magnetic recording medium 1 has the soft magnetic backing layer 3 that guides the magnetic force formed and applied to the substrate in the direction perpendicular to the substrate, and changes the magnetic pole in the direction perpendicular to the substrate. Accordingly, the magnetic recording layer 7 for recording information, the underlayer 5 provided adjacent to the magnetic recording layer 7 on the substrate side for adjusting the orientation of crystal grains of the magnetic recording layer 7, and the magnetic recording layer 7 A recording auxiliary layer 8 which is provided adjacent to the opposite side of the substrate and has a coercive force smaller than that of the magnetic recording layer 7 and records information together with the magnetic recording layer 7 by changing the magnetic pole in a direction perpendicular to the substrate; A protective layer 9 is provided adjacent to the auxiliary recording layer 8 on the side opposite to the substrate and protects the auxiliary recording layer 8. In the perpendicular magnetic recording medium 1, the magnetic recording layer 7 has a granular crystal structure containing at least Co and Pt, and the auxiliary recording layer 8 has a granular crystal structure containing at least Fe and Pt.

  As a result, the perpendicular magnetic recording medium 1 can form both the magnetic recording layer 7 and the recording auxiliary layer 8 with a granular crystal structure to sufficiently separate the crystal grains in the layer and increase the anisotropy. The crystal grains can be sufficiently separated between the magnetic recording layer 7 and the recording auxiliary layer 8 without disturbing the orientation dispersibility of the crystal grains of the layer 8, and thus the recording sensitivity can be improved after increasing the density. A perpendicular magnetic recording medium and a magnetic recording / reproducing apparatus using the perpendicular magnetic recording medium can be realized.

(5) Other Embodiments In the above-described embodiment, the case where the perpendicular magnetic recording medium 1 has the seed layer 4 has been described. However, the present invention is not limited to this, and for example, shown in FIG. Thus, the seed layer 4 may be omitted. In this case, by using an amorphous material for the soft magnetic backing layer 3, it is possible to prevent the underlayer 5 from being affected by the crystal structure of the soft magnetic backing layer 3.

  In the above-described embodiment, the soft magnetic backing layer 3, the seed layer 4, the underlayer 5, the magnetic recording layer 7, the recording auxiliary layer 8, and the protective layer 9 are formed by sputtering. As described above, the present invention is not limited to this, and each layer may be formed by using a laser or microwave, or the film forming method may be changed for each layer.

  Further, in the above-described embodiment, the case where the film thickness of the recording auxiliary layer 8 is measured by the interference color measurement method has been described. However, the present invention is not limited to this, and is substantially the same even when actually measured by a laser or a microscope. Can be obtained.

  Further, in the above-described embodiment, the magnetic recording layer 7 as a magnetic recording layer and the recording auxiliary included in the substrate 2 as the substrate, the soft magnetic backing layer 3 as the soft magnetic backing layer, and the recording layer 6 as the recording layer. Although the case where the perpendicular magnetic recording medium 1 as the perpendicular magnetic recording medium is configured by the recording auxiliary layer 8 as the layer has been described, the present invention is not limited to this, and substrates having various other configurations, and soft The perpendicular magnetic recording medium of the present invention may be constituted by the magnetic backing layer, the magnetic recording layer and the recording auxiliary layer of the recording layer.

  Further, in the above-described embodiment, a magnetic recording / reproducing apparatus as a magnetic recording / reproducing apparatus includes the perpendicular magnetic recording medium 1 as a perpendicular magnetic recording medium, the magnetic head 20 as a magnetic head, and the driving unit 15 as a driving unit. However, the present invention is not limited to this, and the magnetic recording / reproducing apparatus of the present invention is configured by a perpendicular magnetic recording medium, a magnetic head, and a drive unit having various other configurations. You may make it do.

  The present invention can be used, for example, in hard disk drives mounted on various electronic devices.

It is a basic diagram which shows the structure of the perpendicular magnetic recording medium by this Embodiment. It is a basic diagram which shows the structure of a magnetic recording / reproducing apparatus. It is a basic diagram which shows the structure of a magnetic head. It is a basic diagram with which it uses for description of description of a coercive force. It is a basic diagram with which it uses for description of the measurement of the orientation dispersibility by X-ray diffraction. It is a basic diagram which shows the structure of the perpendicular magnetic recording medium by other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Perpendicular magnetic recording medium, 2 ... Substrate, 3 ... Soft magnetic backing layer, 4 ... Seed layer, 5 ... Underlayer, 6 ... Recording layer, 7 ... Magnetic recording layer, 8 ... Recording Auxiliary layer, 9 ... protective layer, 10 ... magnetic recording / reproducing device, 11 ... control unit, 12 ... drive control unit, 13 ... signal processing unit, 14 ... spindle motor, 15 ... drive unit, 20 ... magnetic head, 22 ... main magnetic pole, 25 ... GMR element.

Claims (9)

A perpendicular magnetic recording medium in which at least a soft magnetic backing layer, an underlayer, a recording layer, and a protective layer are sequentially laminated on a substrate,
The recording layer is
A magnetic recording layer formed on the underlayer side and having a granular crystal structure containing at least Co and Pt;
A perpendicular magnetic recording medium comprising: a recording auxiliary layer formed on the protective layer side, having a coercive force smaller than that of the magnetic recording layer, and having a granular crystal structure containing at least Fe and Pt. The recording auxiliary layer is
The perpendicular magnetic recording medium according to claim 1, wherein the thickness is 1 [nm] or more and 5 [nm] or less. The recording auxiliary layer is
The perpendicular magnetic recording medium according to claim 2, wherein the film thickness is 1.5 [nm] or more and 4.0 [nm] or less. The magnetic recording layer is
The perpendicular magnetic recording medium according to claim 2, comprising Cr. The recording auxiliary layer is
The perpendicular magnetic recording medium according to claim 2, comprising Cr. The magnetic recording layer is
The perpendicular magnetic recording medium according to claim 4, comprising TiO ₂ . The recording auxiliary layer is
The perpendicular magnetic recording medium according to claim 5, comprising TiO ₂ . The magnetic recording layer is
Has a hexagonal close-packed lattice crystal structure,
The recording auxiliary layer is
The perpendicular magnetic recording medium according to claim 1, wherein the perpendicular magnetic recording medium has a face-centered cubic lattice crystal structure. A perpendicular magnetic recording medium in which at least a soft magnetic backing layer, an underlayer, a recording layer, and a protective layer are sequentially laminated on a substrate;
A magnetic head for recording information on the perpendicular magnetic recording medium and reading the information recorded on the perpendicular magnetic recording medium;
A drive unit for driving the magnetic head,
The recording layer is
A magnetic recording layer formed on the underlayer side and having a granular crystal structure containing at least Co and Pt;
A magnetic recording / reproducing apparatus comprising: a recording auxiliary layer formed on the protective layer side, having a coercive force smaller than that of the magnetic recording layer and having a granular crystal structure containing at least Fe and Pt.

Images