JP2810046B2 - Magnetic head, method of manufacturing the same, and magnetic recording / reproducing apparatus using the same - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a magnetic head, a method of manufacturing the same, and a magnetic recording / reproducing apparatus using the same, and in particular, a super-sensitive reproducing magnetic head using a superconducting quantum interferometer. The present invention relates to a method of manufacturing the same and a magnetic recording / reproducing apparatus using the same.

[Prior Art] High-density magnetic recording has made remarkable progress, and research on perpendicular magnetic recording suitable for high-density magnetic recording has been advanced in recent years. Densification is progressing.

When the recording density and track density are increased,
Since the area of the recording medium per bit or per wavelength is reduced, the reproduction output is reduced. It has been clarified that when recording is performed by perpendicular magnetic recording, signals with a maximum recording density of 500 KBPI can be recorded. However, when the recorded signal is reproduced by a conventional magnetic head, there is a problem that the output is significantly reduced as compared with a low recording density because the magnetic flux generated from the signal magnetization of the medium is weak. . (Proceedings of the 10th Annual Meeting of the Japan Society of Applied Magnetics (1986) p335) [Problems to be Solved by the Invention] The present invention solves such problems and reproduces recorded signals with extremely high linear recording density and track density. As you can
It is an object of the present invention to provide a reproducing magnetic head with extremely high sensitivity. Another object of the present invention is to provide a method of manufacturing such a magnetic head and a magnetic recording / reproducing apparatus using such a magnetic head.

[Means for Solving the Problems] In order to solve the above problems, in the magnetic head of the present invention, a signal magnetic flux generated from a recording medium flows into a through hole of a superconducting ring constituting a superconducting quantum interferometer. This superconducting quantum interferometer (Super conducting Quantum Interfere
The magnetic flux is detected with high sensitivity by Snce (abbreviated as Snce Device). A superconducting quantum interferometer uses a phenomenon in which a superconducting current flowing through a ring of a superconducting ring including one or two Josephson junctions changes according to the magnetic flux flowing into the through-hole. This is an element that measures sensitivity.

Since this superconducting quantum interferometer utilizes a superconducting state, the device must be made of a superconducting material, and the whole device needs to be cooled to a very low temperature so as to be in the superconducting state. However, the research and development of superconducting materials in recent years has been remarkable, and materials that become superconducting at about 95 ° K have been found. By using such a high-temperature superconducting substance, it becomes possible to configure an ultra-sensitive reproducing magnetic head using a superconducting quantum interferometer.

[Operation] The magnetic head of the present invention is configured such that the surface of the superconducting ring constituting the superconducting quantum interferometer is substantially parallel to the surface of the recording medium, and the through-hole of the superconducting ring into which the magnetic flux flows is elongated. The rectangular hole is formed so that the long side thereof corresponds to the track width, and the short side corresponds to the pole thickness of the single pole type head for perpendicular recording. Further, as compared with the conventional ring type head, the shorter side of the rectangular hole corresponds to the gap length. The superconducting ring may be formed of a thin film or a bulk material. Further, by employing a configuration including a cooling element utilizing the Peltier effect or the like, it is effective in efficiently cooling the superconducting ring and maintaining the superconducting state. In the magnetic head of the present invention, the through hole of the superconducting ring is configured so that the reproducing magnetic flux penetrates, but since the superconducting ring itself is a good magnetic shielding material, it is necessary to prevent unnecessary magnetic flux from entering. Can be done.

[Examples] Next, the present invention will be described in detail using examples. FIG. 1 is a cross-sectional view of one embodiment of the magnetic head of the present invention, and FIG. 2 is a perspective view. The magnetic head of the present invention basically comprises a superconducting ring 1 made of a superconducting material, a Josephson junction 2 connecting the superconducting rings, and a through hole 3 formed by the superconducting ring. The superconducting ring is led out from a conductor 4, and the entire superconducting ring is supported by a support base 5. When a signal is reproduced using the magnetic head of the present invention, the recording medium facing surface 6 and the recording medium 7 are arranged so as to face each other as shown in FIG. Pass through. The current flowing through the conductive wire 4 changes according to the amount of magnetic flux passing through, and the amount of magnetic flux can be detected. In the magnetic head of the present invention, the field W of the through hole of the superconducting ring corresponds to the track width, and the length l corresponds to the pole thickness of the conventional single pole type head for perpendicular recording or the gap length of the conventional ring type head. I do.

In the conventional magnetic head, the reproduction sensitivity decreases as the track width decreases and the pole thickness or the gap length decreases. Therefore, the increase in track density and linear recording density is limited. In this case, the reproduced signal can be sufficiently detected if the amount of magnetic flux passing through the through hole 3 is at least 1 × 10 ⁻¹⁶ Wb. Therefore, the magnetic head of the present invention has extremely high sensitivity. As a result, the track width W and the hole length l can be extremely reduced, and the track density and the linear recording density can be greatly improved.

In the magnetic head of the present invention, unlike the conventional inductive magnetic head, the reproduction output is independent of the relative speed between the head and the tape, and thus is advantageous particularly when used at a low relative speed and at a high linear recording density. Further, it is advantageous in manufacturing a head in that a coil such as an inductive magnetic head is not required. In addition, the conventional magnetoresistive effect type magnetic head had to have a structure in which the magneto-sensitive element was sandwiched between the magnetic shields so that the leakage magnetic flux from other than the recording bit to be reproduced did not enter the magneto-sensitive element. In the magnetic head of the present invention, the superconducting ring 1 itself functions as an extremely effective magnetic shield, shields magnetic fluxes other than recording bits to be reproduced, and prevents the magnetic flux from flowing into the through holes 3. The support substrate 5 made of a non-magnetic insulator functions to support the superconducting ring 1. By incorporating a cooling element utilizing the Bertier effect or the like in this portion, the superconducting ring 1 is effectively cooled, It is effective in keeping the state stable. Further, by using a high magnetic permeability material such as Mn-Zn ferrite as the support substrate 5, the magnetic flux passing through the through-hole 3 can be absorbed by the high magnetic permeability material, and the reproduction efficiency can be improved. The through-hole 3 does not need to be filled with anything. However, in order to prevent foreign matter such as dust from entering, the SiO ₂ , Al ₂ O ₃ ,
A non-magnetic insulator such as glass may be filled.

As the superconducting material used for the magnetic head of the present invention, for example, (Sr _x La _{1 -x} ) ₂ CuO ₄ (x = 0.05 to 0.1) or (Ba _{1 -x} Y _x ) ₃ Cu ₂ O ₇ (X To 0.3) can be used. Particularly, the latter is a preferable material because it becomes a superconductive state at a high temperature of 95 ° K. These materials may be processed into a head shape by processing a sintered bulk material.However, these materials are formed into a thin film by using a thin film forming method such as sputtering, and then processed to form a magnetic head of the present invention. You may.

FIG. 3 shows an example in which a bias coil 9 is combined in the magnetic head of the present invention. FIG. 4A shows a cross section of the magnetic head shown in FIG. 3 at the position of AA '. In the present embodiment, a bias coil 9 is provided between the superconducting ring 7 and the support substrate 5 to interlink with the magnetic flux flowing into the through-hole 3, and an AC bias current is supplied to the bias coil to detect a signal. Can be made easier. The bias coil may be provided with a bias coil 9 on the projection of the support substrate 5 as shown in the sectional view of FIG. 4 (B). In this embodiment, the superconducting ring 1 and the support substrate 5 are made of a bonding material.
Join by 10

FIG. 5 shows an example of a method of manufacturing the magnetic head of the present invention. In FIG. 5A, a block 11 made of a superconducting material is used.
Prepare In (B), the superconducting material block 11
Then, a shallow groove 12 to be the through hole 3 is formed. Machine processing may be used to form the shallow groove, but a resist or the like is attached to a portion other than the processed portion, and the shallow groove is formed by a thin film processing method such as an ion milling method plasma etching method or a wet etching method. The accuracy of the groove size and depth can be improved. Next, in FIG. 5 (B), a thin insulating layer 13 is formed in a portion where a Josephson bond is to be formed by a thin film forming method such as sputtering or vapor deposition. Next, in FIG. 5C, the shallow groove 12 is filled with a binder 14 such as glass. Next, in FIG. 5 (D), the superconducting material blocks 11 are joined together to form a superconducting ring block 15.
And Next, in FIG. 5 (D), the broken line is cut to produce the superconducting ring 1. Next, in FIG. 5 (E), the superconducting ring 1 and the supporting base 5 are connected, and further, the conducting wire 4 is connected to obtain a magnetic head of the present invention. In addition, in FIG. 5D of this embodiment, one block of the superconducting ring block is a block without the shallow groove 12, and finally a magnetic head having a superconducting ring as shown in FIG. 5F. Is also good. Although a thin insulating layer is formed in the portion 13 where a Josephson junction is to be formed in FIG. Just by joining the conductive material blocks, a Josephson junction can be formed with a very small gap at the joining portion.

FIG. 6 shows an example of another method of manufacturing the magnetic head of the present invention. In FIG. 6 (A), on the superconducting material block 11, a portion to be the through hole 3 is made of SiO ₂ or Al _2.
A nonmagnetic insulating material 16 such as O ₃ is formed by a thin film forming method such as sputtering or vapor deposition. A portion where a Josephson junction is to be formed is removed by a thin film processing technique such as ion milling or wet etching. Next, in FIG. 6 (B), a thin insulating layer 13 is formed in a portion to be formed by the Josephson junction, and in FIG. 6 (C), the non-magnetic insulating material 16 and the insulating layer 13 are covered. , Superconducting film 17
Is formed by a thin film forming method such as sputtering or vapor deposition. Further, a superconducting ring is manufactured by cutting along a broken line portion in FIG. 6 (C), and this is connected to a support base as shown in FIG. 5 (E), and a conductor is connected to form a magnetic head. Alternatively, after forming the superconducting film shown in FIG. 6C, the shield block 18 made of a superconducting material is joined using a joining material 19 such as glass in FIG. By manufacturing a superconducting ring, unnecessary leakage magnetic flux from a recording bit can be effectively prevented.

FIG. 7 shows another example of a method of manufacturing a magnetic head according to the present invention. On the support base 5 prepared in FIG. 7A, a superconducting film 17 is formed in FIG. 7B by a thin film forming method such as sputtering or vapor deposition. Next, in FIG. 7 (C), a portion which is not removed is protected with a resist or the like, and an unnecessary portion is removed by a thin film processing method such as ion milling, wet etching, plasma etching,
The through hole 3 and the terminal portion 20 of the superconducting ring 1 are formed.
In this embodiment, the Josephson junction 2 is formed by narrowing the width of the superconducting film. The magnetic head of the present invention can be manufactured by connecting a conducting wire to the terminal portion. Further, in the magnetic head of this embodiment, since the film-shaped superconducting ring 1 faces the recording medium, the superconducting ring 1 may be damaged or worn due to contact with or sliding on the medium. Therefore, as shown in FIG. 7 (D), SiO ₂ , Al ₂ O ₃ , BN,
By attaching a high-hardness non-magnetic insulator as the protective film 21 on the superconducting ring as described above, the above-mentioned breakage and wear can be prevented.

FIG. 8 shows another example of the method of manufacturing a magnetic head according to the present invention. In FIG. 8A, a superconducting film 17 is formed on the support base 5 and a 6
A non-magnetic insulating material 16 is formed in the same manner as shown in FIG. 6A, and an insulating layer 13 is formed in a portion where a Josephson junction is to be formed, as shown in FIG. Thereafter, in FIG. 8B, the superconducting film is formed in the same manner as shown in FIG. 6C.
17 is formed to cover the nonmagnetic insulating material 16 and the insulating layer 13. Further, the conductor 4 is connected to form a magnetic head. In the magnetic head of this embodiment, a block made of a superconductive material may be used instead of the support base 5 and the superconductive film 17 in FIG. Also, as shown in FIG. 8C, a protective film made of a non-magnetic insulator is formed on the superconducting film 17.
8 or a protective material 23 made of a non-magnetic insulator using a bonding material 19 such as glass as shown in FIG.
May be combined.

In the magnetic head of the present invention, all the embodiments have described the magnetic head using the DC superconducting quantum interferometer including two Josephson couplings. The present invention can also be applied to a magnetic head using an AC superconducting quantum interferometer including only one. In this case, as shown in FIG. 4, a high-frequency coil 9 is provided so as to interlink with the magnetic flux passing through the through-hole 3, and only one Josephson coupling 2 of the superconducting ring 1 is provided. Take out.

The magnetic head of the present invention is used for a magnetic head used in sliding contact with a recording medium, such as for a VTR, a floppy disk device, a magnetic table device for a computer, etc. The magnetic recording / reproducing apparatus can reproduce a signal recorded on a medium at a high track density and a high linear recording density with high sensitivity.

In the magnetic head of the present invention, since the sensitivity is too high, it is difficult to measure the amount of magnetic flux when the amount of magnetic flux flowing into the through hole 3 is 10 ^-13 Wb or more. Therefore, when the amount of magnetic flux is set to 10 ^-13 Wb or less, preferably 2 × 10 ^-14 Wb or less, the area of the through hole 3 is reduced or the saturation magnetization of the recording medium is reduced. Should be reduced.

[Effects of the Invention] As described above, the magnetic head of the present invention uses a superconducting quantum interferometer capable of detecting a minute magnetic flux with extremely high sensitivity, and therefore has extremely high sensitivity, and therefore has a narrow track and a short recording bit length. It is also suitable for high-density magnetic recording and reproducing devices.

[Brief description of the drawings]

1 and 4 are sectional views showing an embodiment of the magnetic head of the present invention. FIGS. 2 and 3 are perspective views showing an embodiment of the magnetic head of the present invention. 7 and 8 are perspective views showing one example of a method for manufacturing a magnetic head according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Superconducting ring, 2 ... Josephson junction 3 ... Through-hole 4 ... Conducting wire 5 ... Support base 6 ... Recording medium facing surface 7 ... Recording medium 8 ... Magnetic flux 9 ... Bias coil 10 ... ... joining material 11 ... superconducting material block 12 ... shallow groove 13 ... insulating layer 14, 19 ... bonding material 15 ... superconducting ring block 16 ... nonmagnetic insulating material 17 ... superconducting film 18 ... Superconducting shield 20 ... Terminal 21,22 ... Protective film 23 ... Protective plate

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeo Yamashita 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory (72) Inventor Shinobu Sasaki 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Central Research Laboratory (72) Inventor Yoshinobu Tarutani 1-280 Higashi Koikebo, Kokubunji-shi, Tokyo Hitachi Central Research Laboratory Co., Ltd. .Cl. ⁶ , DB name) G11B 5/127 G11B 5/33

Claims (3)

(57) [Claims] 1. A ring-shaped superconducting quantum interferometer made of a superconducting material including a Josephson junction formed on a nonmagnetic body, and a ring-shaped superconducting quantum interferometer. A magnetic head which detects a magnetic flux by causing a magnetic flux generated from the recording medium to flow into a through hole of the ring by facing a surface of the medium. 2. A shallow groove to be a through hole is formed on first and second blocks made of a superconducting material, an insulating film is formed on a surface of the block on which the shallow groove is formed, and a shallow groove is formed on the first and second blocks. A superconducting ring is formed by filling a binder and joining the first and second blocks to each other, and is formed by joining the superconducting ring and a support base. Production method. 3. A magnetic head having a ring-shaped superconducting quantum interferometer in which a first and second blocks made of a superconducting material are joined to each other on a supporting base made of a nonmagnetic material to form a Josephson junction. By using the above, the surface of the ring of the superconducting quantum interferometer and the surface of the recording medium are arranged to face each other, and the magnetic flux generated from the recording medium flows into the through hole of the ring to detect the magnetic flux. A magnetic recording / reproducing apparatus characterized by the above-mentioned.