JP2000011303A - Magnetic head and two-layer film perpendicular magnetic recording medium and magnetic reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent noise due to the disturbance magnetic field of the two-layered recording medium of the conventional practice in a high- density magnetic recording and reproducing method by a two-layer film perpendicular magnetic recording medium. SOLUTION: A conductive thin film 6 is formed like it is held with a soft magnetic material 5 and one pair or more of electrode terminals are arranged at both ends of the conductive thin film 6 and a high frequency reproduction signal which is modulated by a external magnetic field is reproduced from the electrode terminals of a second pair by impressing a high frequency carrier signal on the electrode terminals of a first pair. Moreover, a DC magnetic field bias is impressed on a two-layered film perpendicular magnetic recording medium 1 with a level near the coercive force of soft magnetic backing layer 3 formed on the medium 1 from a magnetic head having a DC bias impressing means 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-density perpendicular magnetic reproducing method using a two-layer perpendicular magnetic recording medium and an active magnetic head using a high-frequency signal.

[0002]

2. Description of the Related Art In the field of magnetic recording, magnetic tapes and HD
A longitudinal recording / reproducing method of recording on a longitudinal recording medium by a ring type magnetic head has been performed on D. However, in this method, since the recording magnetization is recorded in the longitudinal direction, the demagnetizing field becomes larger as the recording signal has a shorter wavelength, and the recording is hardly performed, and the recording density is limited. On the other hand, in the perpendicular magnetic recording method, magnetization is recorded in the perpendicular magnetic recording layer in the perpendicular direction using a two-layer perpendicular magnetic recording medium composed of a perpendicular magnetic recording layer and a soft magnetic layer film and a single pole type head. This is a recording method that has attracted attention in order to improve the recording density by reducing the demagnetizing field of the recording magnetization as the wavelength becomes shorter.

That is, as a magnetic recording medium, as shown in FIG. 6, a two-layer film in which a perpendicular magnetic layer 2 and a soft magnetic layer 3 (called a backing layer) such as permalloy are formed on a substrate such as glass as a lower layer. The signal magnetization 10 recorded on the perpendicular recording layer 2 using the perpendicular magnetic recording medium is transmitted through the backing layer 3 by the signal magnetic flux 9 reproduced by the single pole type magnetic head of the perpendicular head, that is, as if a part of the head. To form a closed magnetic circuit.

However, the magnetic recording medium is composed of a perpendicular magnetic recording layer and a soft magnetic layer. In particular, against a disturbance magnetic field in the horizontal direction, a magnetic flux 2 entering from a backing layer 3 which is a high magnetic permeability layer of a magnetic recording medium is used.
1 is sucked up by a single pole head and winding 2
2 and is detected as a noise component between the reproduction terminals 23 and 24. Since this soft magnetic layer has a high magnetic permeability and a large area, the magnetic field induced in the soft magnetic layer having the entire area concentrates on a single pole, so that a large level of noise is picked up. is there.

On the other hand, inductive heads such as a ferrite head, a MIG head, and a thin film head have been put to practical use as a magnetic head for a hard disk (HDD).

In recent years, a magnetoresistive (MR) head has been put to practical use as a reproducing head. In such a head, when a disturbance DC magnetic field is applied from the outside, the symmetry of the waveform is lost and an error occurs in signal processing. This is called asymmetry.

FIG. 7 is a report of the IEICE Technical Report MR95-85, which proposes an element and a head using a change in magnetic impedance. FIG. 7 shows that a lead 25 made of a conductive metal thin film extends over a track width 26 along with a permalloy film 27 and a laminated film 29 of SiO2 film 29 and 3.
5 illustrates the operating principle of a magneto-impedance element sandwiched by soft magnetic cores of zero. A high-frequency signal is applied from a UHF-band high-frequency transmitter 31 through a resistor 32 to supply a current 33, and a current is applied between the terminals based on a change in magnetic impedance between terminals 34 and 35 provided at both ends of the lead 25. This is to detect the voltage change of. When there is no signal magnetic field generated from the magnetization 37 on the magnetic recording medium 36, a UHF carrier corresponding to the product of the current 33 and the impedance between the terminals 34 and 35 of the lead 25 is provided between the terminals 34 and 35. When a signal voltage is generated and a signal magnetic field is received from the magnetic recording medium, the easy magnetization direction of the soft magnetic core of the element is oriented in the track width direction. The magnetic impedance decreases. Therefore, UH
The F carrier signal is amplified by the signal magnetic field of the magnetic recording medium.
It is detected in a modulated form. AM
The signal magnetization 3 on the magnetic recording medium 36 is detected by the detection.
7 can be read out. When this head is realized, the giant MR currently under development
It is expected that there is a possibility that about 10 times the output can be obtained from the head. FIG. 8 shows the operation curve of the device shown in FIG. That is, the high-frequency voltages detected at the terminals 34 and 35 are plotted. A high frequency voltage detected at terminals 34 and 35 was obtained by applying a dc magnetic field to the above element at the center of the Helmholtz coil with the carrier signal frequency being 1.0 GHz. When the value of the DC magnetic field is 0, the high-frequency voltage detected at the terminals 34 and 35 is the largest. As the DC magnetic field is increased, the terminals 34,
The high frequency voltage detected at 35 decreases. As can be seen from FIG. 8, this DC magnetic field corresponds to the signal magnetic field on the magnetic recording medium 36, and in order to reproduce a signal with high sensitivity and obtain a waveform with small distortion, it is necessary to set DC bias 38 points. That is, when a DC magnetic field corresponding to the 38 points is applied to the element, the voltage is substantially linearly changed in the vicinity of the 38 points, so that the distortion is small. In the above model, a carrier signal and a DC current are caused to flow through the lead 25 to generate a DC magnetic field, which is used as a bias.

[0008]

As described above, it is desired to realize a high-density magnetic recording / reproducing method using a two-layer perpendicular magnetic recording medium. As described above, the conventional two-layer recording medium induces noise. In addition, there has been a problem that the conventional magnetic head is apt to be asymmetry with respect to a disturbance magnetic field generated from a geomagnetism or a motor.

The present invention considers the problem that such a conventional magnetic reproducing method is likely to induce noise, and combines this characteristic with the characteristic of an MI head which originally requires a DC bias, thereby realizing a double-layer perpendicular magnetic recording method. It is an object of the present invention to provide a magnetic recording / reproducing method for effectively preventing noise due to a generated disturbance magnetic field.

[0010]

In order to solve the above-mentioned problems, a first aspect of the present invention (corresponding to claim 1) is to form a conductive thin film between soft magnetic materials and to form the conductive thin film. At least two pairs of electrode terminals are arranged at both ends of the thin film, a high-frequency carrier signal current and a DC bias current are simultaneously applied to the first pair of electrode terminals, and a high-frequency reproduction signal modulated by a recording magnetic field from the second pair of electrode terminals. When a two-layer perpendicular magnetic recording medium using a perpendicular recording layer and a soft magnetic layer film is to be reproduced,
A magnetic reproducing method characterized in that a DC magnetic field bias caused by the DC bias current is set to a value near a coercive force of the soft magnetic layer film.

The second invention (corresponding to claim 2) is:
A conductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, a high-frequency carrier signal is applied to a first pair of electrode terminals, and a second pair of electrode terminals is applied. A magnetic recording method using a magnetic head for reproducing a high-frequency reproduction signal modulated by a recording magnetic field from the electrode terminals and applying a DC magnetic field bias to the soft magnetic material, wherein a two-layer film using a perpendicular recording layer and a soft magnetic layer film is used. When a perpendicular magnetic recording medium is to be reproduced, the DC magnetic field bias is set to a value close to the coercive force of the soft magnetic layer film by DC bias applying means provided in a part of the magnetic head. Is the way.

A third aspect of the present invention (corresponding to claim 3) is:
The magnetic reproducing method according to the first or second invention, wherein the coercive force of the soft magnetic layer film is larger than a disturbance magnetic field.

A fourth aspect of the present invention (corresponding to claim 4) is:
4. The double-layered perpendicular magnetic recording medium according to any one of the first to third inventions, wherein the soft magnetic layer film is a laminated film composed of a metal magnetic layer film and an insulating layer film. This is a magnetic reproduction method.

A fifth aspect of the present invention (corresponding to claim 5) is:
A conductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, and a high-frequency carrier signal current and a DC bias current are simultaneously applied to the first pair of electrode terminals. In a magnetic head that reproduces a high-frequency reproduction signal modulated by a recording magnetic field from a second pair of electrode terminals, when a two-layer perpendicular magnetic recording medium using a perpendicular recording layer and a soft magnetic layer film is to be reproduced, A magnetic head, wherein a DC magnetic field bias due to the DC bias current is set to a value near a coercive force of the soft magnetic layer film.

A sixth aspect of the present invention (corresponding to claim 6) is:
A conductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, a high-frequency carrier signal is applied to a first pair of electrode terminals, and a second pair of electrode terminals is applied. A two-layer perpendicular magnetic recording medium using a perpendicular recording layer and a soft magnetic layer film in a magnetic head for reproducing a high frequency reproduction signal modulated by a recording magnetic field from the electrode terminals of the magnetic head and applying a DC magnetic field bias to the soft magnetic material. Wherein the DC magnetic field bias from the DC bias applying means formed in a part of the magnetic head is set to a value close to the coercive force of the soft magnetic layer film. is there.

A seventh aspect of the present invention (corresponding to claim 7) is:
A conductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, and a high-frequency carrier signal current and a DC bias current are simultaneously applied to the first pair of electrode terminals. A two-layered perpendicular magnetic recording medium using a perpendicular recording layer and a soft magnetic layer to reproduce a high-frequency reproduction signal modulated by a recording magnetic field from a second pair of electrode terminals. , Wherein the coercive force value of the soft magnetic layer film is a value near a coercive force of a DC magnetic field bias due to the DC bias current of the magnetic head.

According to an eighth aspect of the present invention (corresponding to claim 8),
A conductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, a high-frequency carrier signal is applied to a first pair of electrode terminals, and a second pair of electrode terminals is applied. A high-frequency reproduction signal modulated by a recording magnetic field is reproduced from the electrode terminals of the magnetic recording medium, and reproduced by a magnetic head that applies a DC magnetic field bias to the soft magnetic material, using a perpendicular recording layer and a soft magnetic layer film. In the dual-layer perpendicular magnetic recording medium, the coercive force value of the soft magnetic layer film is a value close to the coercive force of the DC magnetic field bias from a DC bias applying unit formed in a part of the magnetic head. Is a two-layer perpendicular magnetic recording medium.

According to a ninth aspect of the present invention (corresponding to claim 9), the coercive force value of the soft magnetic layer film is larger than a disturbance magnetic field. This is a layered perpendicular magnetic recording medium.

The tenth aspect of the present invention (corresponding to claim 10)
The two-layer perpendicular magnetic recording according to any one of the seventh to ninth aspects, wherein the soft magnetic layer film is a laminated film including a metal magnetic layer film and an insulating layer film. Medium.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. (Embodiment 1) First, a first embodiment will be described with reference to the drawings.

FIG. 1 shows a conceptual diagram of the magnetic recording / reproducing method of the present invention. FIG. 2 is a view of the single pole portion of the MI head constituting a part of the present invention viewed from the direction of P in FIG. FIG. 3 is a graph comparing the characteristics of the backing layer of the magnetic recording medium of the present invention with those of the conventional backing layer.
It shows an H curve. In FIG. 1, a two-layer perpendicular magnetic recording medium 1 includes a glass substrate 4 of a disc-like substrate, a backing layer 3 mainly composed of a soft magnetic material, and a perpendicular recording layer 2. The magnetic head flies at a certain distance d from the perpendicular recording layer 2 to read signals recorded on the perpendicular recording layer. In this case, although not shown in the drawing, this magnetic head is mounted on a slider of a hard disk drive and floats at a fixed distance on a rotating hard disk (here, a two-layer perpendicular magnetic recording medium). .

The magnetic head is constructed by sandwiching a conductive thin film of copper between single poles 5, which are main poles made of permalloy. The principle of taking out signals from both ends of the conductive thin film 6 during reproduction is shown in FIG. As shown.

In this case, the signal magnetization 10 on the perpendicular recording layer 2
The signal flux 9 from the substrate passes through the vertical return core 7 and the backing layer 3 to form a closed loop. The magnetic flux is detected by the MI effect. FIG. 2 shows the single pole 5 viewed from the direction of P in FIG. This will be described in comparison with FIG. A high-frequency current is applied from a high-frequency transmitter 16 to a pair of terminals 13 and 14 of the conductive thin film formed on the single pole 5 via a resistor 15. One more
An electric circuit is connected to the pair of terminals 11 and 12 to detect a voltage drop.

In the magnetic reproducing method of the present invention, the characteristic 18 having a coercive force larger than the magnetic field intensity of the disturbance is set to the characteristic 18 of the conventional underlayer in FIG. Usually, the magnetic field strength of the disturbance is 10 Oe or less. That is, this backing layer was set as a soft magnetic film having a slight coercive force of 10 Oe.

With this setting, for a disturbance magnetic field of 10 Oe or less, the gradient of B / H is small as shown by the point (b) in FIG. 3, that is, the magnetic permeability of the backing layer is small. It was found that a disturbance magnetic field induced from the perpendicular magnetic recording medium to the magnetic head hardly occurred. It was also found that when a DC current was applied from the winding 8 of the magnetic head to generate and increase the DC magnetic field bias, the output at the terminals 11 and 12 suddenly increased. At this time, as shown by the point (a) in FIG. 3, when the DC magnetic field bias is set near 100 Oe, it is considered that the gradient of B / H increases, that is, the differential permeability increases. When a predetermined coercive force is set as the backing layer of the perpendicular magnetic recording medium, the differential magnetic permeability increases near the coercive force, and a region having a high magnetic permeability can be used.

Therefore, while the magnetic permeability of the characteristic 18 of the soft magnetic layer of the conventional backing layer shown in FIG. 3 is large, the influence of the disturbance magnetic field is large, whereas the DC magnetic field bias is applied to the medium of the present invention. Since the magnetic permeability is low in the non-existing area, there is no influence by a disturbance magnetic field or the like, and therefore, the above-mentioned problem is solved such that noise is not induced from the entire surface of the magnetic disk. On the other hand, in the MI head, a DC magnetic field bias is necessary in order to use a region where the sensitivity and distortion of a signal are reduced. In the present invention, the DC magnetic field bias and the DC magnetic field bias applied to the backing layer of the two-layer magnetic recording medium are commonly used.
That is, a DC magnetic field bias is generated by applying a DC current to the winding 8 of the magnetic head. This DC magnetic field bias may erase the magnetization recorded in the perpendicular recording layer, but if the coercive force of the perpendicular recording layer is set to 1200 Oe sufficiently large, the output only attenuates within 0.5 dB only for the first time,
After that, it was found that there was no attenuation and there was no practical problem.

Further, the characteristics of the present invention will be described in detail with reference to FIG. FIG. 4 shows a result obtained by measuring a 0.5 μm permalloy film used as a backing layer of the magnetic recording medium of the present invention by a magnetic permeability measuring apparatus. 200MHz permeability property 1
7 has a maximum magnetic permeability with a DC bias of 10 Oe and 1 GHz
Then, the DC bias value of 10 Oe tends to increase,
The permeability 18 has decreased. For use in the MI head, a characteristic that can be used even at 1 GHz or more is required because the carrier signal is high. This is thought to be due to eddy currents. (Embodiment 2) Next, a second embodiment will be described with reference to the drawings.

FIG. 5 shows that the backing layer is made of permalloy and SiO2.
And the characteristics of the laminated film. Permalloy film 1000nm, Si
An O2 film of 50 nm was used as ten laminated films. 200MH characteristics 19 and 1
It can be seen that the GHz characteristics 20 substantially match. By forming the backing layer in this manner, the magnetic permeability of the backing layer in only the portion applied from the magnetic head is improved, and the backing layer functions as an original backing layer. In other parts, since the magnetic permeability is low and it does not respond to the magnetic field of disturbance, a high-quality signal can be obtained as a whole.

The terminals of the present invention are not limited to the two pairs in the above-described embodiment, and a terminal for applying a high-frequency signal and a terminal for applying a DC current for generating a DC magnetic field bias are separately provided. In other words, it is sufficient if the configuration is such that a DC magnetic field bias and a high-frequency signal can be applied, for example, three pairs of terminals are used in combination with the terminals for detecting the DC voltage.

Further, the DC magnetic field bias of the present invention is not limited to the DC magnetic field bias generated by applying the DC current to the winding of the magnetic head in the above-described embodiment, and two or more pairs of conductive thin films are provided. In other words, any device that can generate a DC magnetic field bias, such as a device that generates a DC magnetic field bias by applying a DC current to a newly provided conductive thin film, may be used.

Further, the coercive force of the backing layer of the present invention is not limited to 10 Oe in the above-described embodiment, but may be, for example, 20 Oe or 5 Oe as long as it has a coercive force larger than the disturbance magnetic field.

Further, the substrate of the present embodiment is not limited to the glass substrate in the above-described embodiment, but may be a quartz substrate or the like.
In short, it only needs to be a substrate on which a backing layer and a perpendicular recording layer can be formed.

[0033]

As apparent from the above description, the present invention applies a DC bias magnetic field to both the DC bias of the MI head and the double-layer perpendicular magnetic recording medium, and backs the double-layer perpendicular magnetic recording medium. By setting the coercive force of the layer near the DC bias level of the MI head, it is possible to provide a magnetic recording / reproducing method that is resistant to a disturbance magnetic field.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a magnetic recording / reproducing method using an MI head and a two-layer perpendicular magnetic recording medium according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a magnetic recording / reproducing MI element according to the present invention;

FIG. 3 is a characteristic diagram of a backing layer of the magnetic recording medium of the present invention.

FIG. 4 is a characteristic diagram of a backing layer of the magnetic recording medium of the present invention.

FIG. 5 is a characteristic diagram of a backing layer of the magnetic recording medium according to the second embodiment of the present invention.

FIG. 6 is a schematic diagram of a perpendicular magnetic recording system using a film perpendicular magnetic recording medium according to an embodiment of the present invention.

FIG. 7 is a diagram of an operation principle of an MI head according to a conventional invention.

FIG. 8 is a diagram of an operation principle of an MI head according to a conventional invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 double layer perpendicular magnetic recording medium 2 perpendicular recording layer 3 backing layer 4 glass substrate 5 single pole 6 conductive thin film 7 return core 8 magnetic head winding 9 signal magnetic flux 10 signal magnetization 11 terminal 12 terminal 13 terminal 14 terminal 15 resistance 16 High-frequency oscillator 17 Characteristics of the backing layer of the present invention 18 Characteristics of the conventional backing layer 19 200 MHz characteristics 20 1 GHz characteristics 21 Magnetic flux 22 Winding 23 Reproduction terminal 24 Reproduction terminal 25 Lead 26 Track width 27 Permalloy film 28 SiO2 film 29 Soft magnetism Core 30 Soft magnetic core 31 High frequency oscillator 32 Resistance 33 Current 34 Terminal 35 Terminal 36 Magnetic recording medium 37 Magnetization 38 DC bias 39 200 MHz characteristic 40 1 GHz characteristic 41 DC bias winding

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Sayuri Muramatsu 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 5D091 AA10 CC12 HH08

Claims (10)

[Claims] An electroconductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, and a high-frequency carrier signal current and a direct current are applied to a first pair of electrode terminals. In a magnetic reproducing method using a magnetic head that simultaneously applies a bias current and reproduces a high-frequency reproduction signal modulated by a recording magnetic field from a second pair of electrode terminals, a two-layer perpendicular magnetic system using a perpendicular recording layer and a soft magnetic layer film When a recording medium is to be reproduced, a DC magnetic field bias due to the DC bias current is set to a value near a coercive force of the soft magnetic layer film. 2. A conductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, and a high-frequency carrier signal is applied to the first pair of electrode terminals. And reproducing a high-frequency reproduction signal modulated by a recording magnetic field from a second pair of electrode terminals and applying a DC magnetic field bias to the soft magnetic material. When the used two-layer perpendicular magnetic recording medium is to be reproduced, setting the DC magnetic field bias to a value close to the coercive force of the soft magnetic layer film by a DC bias applying unit formed in a part of the magnetic head. Characteristic magnetic reproduction method. 3. The magnetic reproducing method according to claim 1, wherein a coercive force of the soft magnetic layer film is larger than a disturbance magnetic field. 4. The two-layer perpendicular magnetic recording medium according to claim 1, wherein the soft magnetic layer film is a laminated film composed of a metal magnetic layer film and an insulating layer film. The magnetic reproduction method according to any one of the above. 5. A conductive thin film is sandwiched by a soft magnetic material, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, and a high-frequency carrier signal current and a direct current are applied to a first pair of electrode terminals. In a magnetic head that simultaneously applies a bias current and reproduces a high-frequency reproduction signal modulated by a recording magnetic field from a second pair of electrode terminals, a two-layer perpendicular magnetic recording medium using a perpendicular recording layer and a soft magnetic layer film is reproduced. In a magnetic head, a DC magnetic field bias due to the DC bias current is set to a value near a coercive force of the soft magnetic layer film. 6. A conductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, and a high-frequency carrier signal is applied to the first pair of electrode terminals. A magnetic head for reproducing a high-frequency reproduction signal modulated by a recording magnetic field from a second pair of electrode terminals and applying a DC magnetic field bias to the soft magnetic material, wherein a two-layer structure using a perpendicular recording layer and a soft magnetic layer film is provided. When a film perpendicular magnetic recording medium is to be reproduced, the DC magnetic field bias from a DC bias applying unit formed in a part of the magnetic head is set to a value close to the coercive force of the soft magnetic layer film. Magnetic head. 7. A conductive thin film is sandwiched between soft magnetic materials, two or more pairs of electrode terminals are arranged at both ends of the conductive thin film, and a high-frequency carrier signal current and a DC A magnetic head that applies a bias current at the same time and reproduces a high-frequency reproduction signal modulated by a recording magnetic field from a second pair of electrode terminals is reproduced by a magnetic head, and includes a perpendicular recording layer and a soft magnetic layer film. The perpendicular magnetic recording medium according to claim 1, wherein the coercive force value of the soft magnetic layer film is a value near a coercive force of a DC magnetic field bias caused by the DC bias current of the magnetic head. 8. A conductive thin film sandwiched by a soft magnetic material, two or more pairs of electrode terminals disposed at both ends of the conductive thin film, and a high-frequency carrier signal applied to a first pair of electrode terminals. And reproducing a high-frequency reproduction signal modulated by a recording magnetic field from the second pair of electrode terminals, and reproducing the reproduced signal by a magnetic head that applies a DC magnetic field bias to the soft magnetic material. 2 using layer film
In the layered perpendicular magnetic recording medium, the coercive force value of the soft magnetic layer film is a value near the coercive force of the DC magnetic field bias from a DC bias applying unit formed in a part of the magnetic head. A two-layer perpendicular magnetic recording medium. 9. The method according to claim 7, wherein a coercive force value of the soft magnetic layer film is larger than a disturbance magnetic field.
Layered perpendicular magnetic recording medium. 10. The two-layer film according to claim 7, wherein the soft magnetic layer film is a laminated film including a metal magnetic layer film and an insulating layer film. Magnetic recording medium.