Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2002-04-01
2004-09-14
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06791794
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a magnetic head for recording information on a magnetic recording medium, to a method of manufacturing the magnetic head, and to a magnetic storage unit using the magnetic head.
A magnetic recording medium is disclosed, for example, in Japanese Unexamined Patent Publication of Tokka:. No. Hei 9-138,930 (or JP-A 9-138930). JP-A 9-138930 provides a magnetic recording medium to obtain high magnetic characteristics and to improve adhesion property between a substrate and a base layer. According to JP-A 9-138930, first base layers, second base layers magnetic layers and lubricant layers are successively formed on a substrate. Among the base layers, the first base layers formed near the substrate have higher specific heat than that of the second base layers deposited far from the substrate. Thereby, the temperature in orientation controlling layers and magnetic layers can be enough raised without increasing the temperature in the inside and surface of the substrate so much. Thereby, adhesion property between the first base layers and the substrate can be improved, which prevents peeling of the first base layers.
The magnetic storage units may be a magnetic disk drive. In the magnetic disk drive, data is written and read by thin film magnetic transducers called “magnetic heads” which are supported over a surface of the magnetic recording medium or disk while it is rotated at a high speed. The magnetic head are supported by a thin cushion of air (an “air bearing”) produced by the disk's high rotational speed.
With miniaturization and large-capacity in the magnetic storage unit, a volume per one bit recorded on the magnetic recording medium drastically becomes small. In the manner which is well known in the art, there is a magnetoresistive (MR) head to detect, as a large read output, a magnetic signal generated from a microscopic bit.
Inasmuch as the MR head is exclusively used for reading, the MR head is used as a merged MR head which employs the MR head and an inductive (ID) head for writing in combination. Such as a merged MR head is disclosed, for example, in U.S. Pat. No. 5,438,747, Japanese Unexamined Patent Publication of Tokkai No. Hei 8-212,512 (or JP-A 8-212512), and Japanese Granted Patent Publication of No. 2,821,456 (or JP-B 2821456) which corresponds to U.S. patent application Ser. No. 09/108,252).
U.S. Pat. No. 5,439,747 provides a merged MR head having vertically aligned sidewalls so as to minimize side-fringing and improve off-track performance. When a magnetic recording disk is rotated, a thin film merged MR head, mounted on a slider, is supported above a surface of the magnetic recording disk by a thin layer of air called an “air bearing”. The merged MR head includes an MR read head and an IR write head. The bottom surface of the slider and the merged MR head are in the plane of an air bearing surface (ABS) of the slider. The MR read head includes a magnetoresistive element MR which is sandwiched between first and second gap layers, the gap layers in turn being sandwiched between first and second shield layers. The first and second gap layers are collectively called a magnetic separation layer. In a merged MR head, the second shield layer of the MR read head also serves as the bottom pole piece for the IR write head. The bottom pole piece is called a first or lower magnetic layer. The IR write head has a pole tip region which is located between the air bearing surface (ABS) and a zero throat level and a yoke or back region which extends back from the zero throat level to and including a back gap. The IR write head includes the bottom pole piece and a top pole piece. The top pole piece is called a second or upper magnetic layer. The bottom pole piece comprises the second shield layer of the MR read head. Each pole piece also has a back layer portion which is located in the back region, the back layer portions of the pole pieces being magnetically connected at the back gap (BG). The bottom pole piece includes a pole tip structure which is located in the pole tip region between the ABS and the zero throat level. This pole tip structure includes a bottom pole tip element and a top pole tip element. The top pole piece includes a pole tip structure which is located in the pole tip region between the ABS and the zero throat level. This pole tip structure includes a top pole tip element. The pole tip elements are integrally formed from second shield of the MR read head. A pole gap layer (G) is sandwiched between the pole tip elements.
JP-A 8-212512 discloses a magnetic head for a high recording density in a high-frequency region. Specifically, JP-A 8-212512 discloses a recording and reproducing separated type head which comprises an inductive (IR) write head, a magnetoresistive (MR) read head, and a shield member for preventing the MR read head from being confused due to a leakage magnetic field. The MR read head comprises a lower shield layer formed on a substrate, a magnetoresistance effect layer, electrodes, and an upper shield layer. The IR write head comprises a lower magnetic layer, a write coil, and an upper magnetic layer.
JP-B 2821456 discloses a merged MR head which comprises a MR read head and an IR write head. The IR write head comprises a lower magnetic layer, an insulating layer formed on the lower magnetic layer, a write coil enclosed with the insulating layer, and an upper magnetic layer formed on the insulating layer. The write coil is a patterned conductive layer. The MR read head comprises a lower shield layer, a gap layer formed on the lower shield layer, a magneto-resistance effect element sandwiched in the gap layer at one end thereof, an upper shield layer formed on the gap layer. The lower magnetic layer is the upper shield layer itself.
Recently, a giant magnetoresistive (GMR) read head is made practicable. The GMR read head uses a GMR effect which is capable of realizing a drastic high output in comparison with the MR read head. The GMR read head generally uses a spin valve effect. The “spin valve effect” is a phenomenon where a variation of resistance corresponds to a cosine between magnetic directions of two adjacent magnetic layers and thereby a large variation of resistance is obtained by a small operational magnetic field. Such a GMR read head using the spin valve effect is disclosed, for example, in Japanese Unexamined Patent Publications of Tokkai No. Hei 10-162,322 (or JP-A 10-162322) and Tokkai No. Hei 11-16,120 (or JP-A 11-16120).
JP-A 10-162322 provides a merged GMR head that realizes simultaneously the magnetizing direction of the magnetization fixing layer of a spin valve element and the magnetic anisotropic direction of a magnetic shield or a recording magnetic pole, and that can secure a stable operation of a magnetoresistence effect (MR) read head part and an indudtive (ID) write head part. The merged GMR head disclosed in JP-A 10-162,322 is equipped with an MR read head part having a reproducing function and an ID write head part recording prescribed information on a magnetic recording medium with a magnetic gap part. An MR element is constituted of a center area and end areas. The center area consists of spin valve elements and senses a media magnetic field. The end areas supply a bias magnetic field and an electric current. The other magnetic pole of the ID write head part is constituted of two kinds of laminated magnetic films having a different degree of saturation magnetization. The saturation magnetization of the magnetic film close to a magnetic gap inside each magnetic film is set to be larger than that of the magnetic film away from the magnetic gap.
JP-A 11-16120 provides a magnetic domain structure which may be optimized even without the execution of the head treatment. JP-A 11-16120 discloses a recording and reproducing separated-type head using a thin film magnetic head. The recording and reproducing separated-type head comprises a reproducing or read head and a recording or write head. The reproducing head comprises a magnetoresistence effect film which is san
Hayashi Kazuhiko
Honjo Hiroaki
Ishi Tsutomu
Ishiwata Nobuyuki
Nonaka Yoshihino
Castro Angel
Heinz A. J.
Katten Muchin Zavis & Rosenman
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