Tdk Corporation

Akebono Brake Industry Co., Ltd.

Other

Akebono Research and Developement Centre Ltd.

Mikio Matsuzaki

Kazumasa Fukuda

Tetsuya Roppongi

Masanori Sakai

Hiroshi Ikeda

Isamu Sato

Joichiro Ezaki

Makoto Yoshida

Haruyuki Morita

Noboru Yamanaka

Tsutomu Aoyama

Yuzuru Iwai

Takamitsu Tsuna

Shunichi Katase

Monjiro Momoi

Toru Yoshino

Toshitaka Izumihara

Atsuo Kobayashi

Atsushi Iijima

Shinichi Horinouchi

Junichi Sato

Masashi Sahashi

Daisuke Miyauchi

Yoshiaki Ito

Norikazu Ota

Akihiko Takeo

Tatsuo Shibata

Tomoko Taguchi

Yoshiaki Tanaka

Noriyuki Ito

Rachid Sbiaa

Takuya Adachi

Yasufumi Uno

Yuichi Watabe

Tsutomu Koyanagi

Koichi Shinohara

Tomohiro Nozaki

Nobuya Ohyama

Yoshiaki Itoh

Jun Shouzi

A magnetic recording system including follows: a recording head, a recording medium that includes a first recording medium layer, a second recording medium layer, and a substrate. The magnetic recording system includes an electric field applying device applying an electric field and a magnetic field applying device applying a magnetic field to the recording medium, a movement mechanism that moves them to an arbitrary position. The magnetic recording system has a function of controlling an applying direction of at least one of the electric field applying device and the magnetic field applying device, and the recording head is arranged at a position facing the recording medium.

Magnetic recording system and magnetic recording device

A measuring circuit system in a magnetic field measuring apparatus of the invention has an amplifier and a band-pass filter connected in sequence on an output terminal side of the TMR element, the band-pass filter is a narrow-range band-pass filter such that a peak pass frequency of the filter that is a center is a basic frequency selected from a range of 10 to 40 GHz and a band width centered around the basic frequency is a narrow range of &#xb1;0.5 to &#xb1;4 GHz; and with the measuring circuit system, an S/N ratio (SNR) of 3 dB or greater is obtained, the SNR being defined by a ratio of an amplitude S of a high-frequency generated signal induced by the TMR element to a total noise N that is a sum of a head noise generated by the TMR element and a circuit noise generated by the amplifier. With such a configuration, an in-plane high-frequency magnetic field generated by a microwave-assisted magnetic head is reliably and precisely measured.

Apparatus for measuring magnetic field of microwave-assisted head

A measuring circuit system in a magnetic field measuring apparatus of the invention has an amplifier and a band-pass filter connected in sequence on an output terminal side of the TMR element, the band-pass filter is a narrow-range band-pass filter such that a peak pass frequency of the filter that is a center is a basic frequency selected from a range of 10 to 40 GHz and a band width centered around the basic frequency is a narrow range of &#xb1;0.5 to &#xb1;4 GHz; and with the measuring circuit system, an SIN ratio (SNR) of 3 dB or greater is obtained, the SNR being defined by a ratio of an amplitude S of a high-frequency generated signal induced by the TMR element to a total noise N that is a sum of a head noise generated by the TMR element and a circuit noise generated by the amplifier. With such a configuration, an in-plane high-frequency magnetic field generated by a microwave-assisted magnetic head is reliably and precisely measured.

A magnetic recording apparatus includes a magnetic recording medium having a magnetic recording layer, a thin-film magnetic head with a microwave-band magnetic drive function, the head having a write field generation means that generates a write field to the magnetic recording medium in response to a write signal, and a microwave generator that is provided independent of the write field generation means and generates an alternating magnetic field in plane having a microwave-band frequency when microwave-excitation current is fed, an excitation current generation means that generates the microwave-excitation current by amplitude-modulating microwave carrier current with a modulating signal having a fixed period, and a write signal supply means that generates the write signal and applies it to the write field generation means of the thin-film magnetic head.

Magnetic recording apparatus provided with microwave-assisted head

Provided is a thin-film magnetic head capable of writing data with high accuracy on a magnetic recording medium having high coercive force without heating. The head comprises an electromagnetic coil element comprising: a main magnetic pole; an auxiliary magnetic pole; and a write coil formed so as to pass through at least between the main magnetic pole and the auxiliary magnetic pole, for generating the write magnetic field. In this head, a part of the write coil has a layered structure of: a resonance coil layer for generating a resonance magnetic field having ferromagnetic resonance frequency of a magnetic recording layer of a magnetic recording medium or having a frequency in the vicinity thereof; and a write coil layer. And further, the resonance coil layer and the write coil layer sandwich an insulating layer therebetween.

Magnetic recording method using ferromagnetic resonance and thin-film magnetic head for using the method

The thin-film magnetic head of the present invention is provided with an antiferromagnetic layer, a pinned layer whose direction of magnetization is fixed by exchange-coupling with the antiferromagnetic layer, a free layer whose direction of magnetization varies according to external magnetic field, an intermediate layer disposed between the pinned layer and free layer, and a pair of electrode layers for supplying a sense current in a layer thickness direction of the free layer. One electrode layer is connected to the pinned layer. Due to this configuration, a sense current flows through the free layer, the intermediate layer, and the pinned layer, but basically does not flow through the antiferromagnetic layer. As a consequence, the antiferromagnetic layer does not contribute to total resistance of the magnetoresistance element, allowing a high magnetoresistance ratio to be obtained.

Thin-film magnetic head for reading magnetic information on a hard disk by utilizing a magnetoresistance effect

A perpendicular magnetic recording apparatus includes a perpendicular double-layer film medium including a stack of a soft magnetic backing layer and a perpendicular magnetic recording layer in which recording is performed under a condition that a recording track pitch as a total of a recording track width and a guard-band width between recording tracks is set to be 1 &mgr;m or less, and a perpendicular magnetic recording head including a recording main pole, an auxiliary pole disposed at a gap having a length of five or less times the guard-band width with respect to the recording main pole, and an exciting coil.

Perpendicular magnetic recording head having narrow recording gap and perpendicular magnetic recording apparatus using the same

A method of maintaining a constant flying height of a magnetic head: adapted to maintain a flying height of a magnetic head on a magnetic disk substantially constant irrespective of a change of a skew angle, utilizing a device comprising a magnetic disk, a positioning device, a head supporting device and a magnetic head; said positioning device supporting one end of said head supporting device and rotating the head supporting device on a first plane placed on a second plane of said magnetic disk within a predetermined skew angle range; the head supporting device supporting said magnetic head at the other end thereof; the magnetic head being attached with reading/writing elements at an air discharge end of a slider having flying planes on a side of a third plane thereof opposing the magnetic disk; a thickness of said slider from each of the flying planes to an opposite surface on the reverse side thereof being 0.65 mm or less; a length in a first direction of air discharge thereof being 3 mm or less, and a width in a second direction orthogonal to the first direction of air discharge thereof being 2.5 mm or less; wherein a change of the flying height of the magnetic head on the magnetic disk is 0.02 &mgr;m or less, when the skew angle is changed in a range of &minus;20 to 20 degree.

Method of maintaining a constant flying height of a magnetic head and a magnetic disk drive utilized therefor

A perpendicular magnetic recording apparatus includes a magnetic disk having a perpendicular double-layer film and a perpendicular magnetic recording head having a leading pole positioned forward along the head traveling direction, a trailing pole positioned backward along the head traveling direction at a gap length from the leading pole and having, in an air-bearing surface, a forward pole and a rearward pole of which saturation magnetic flux density is higher than that of the forward pole, and an exciting coil. A length p of the trailing pole along the head traveling direction is longer than a length T of the trailing pole in a track width direction, the length p is longer than the gap length g , and a length p of the rearward pole is shorter than a length p of the forward pole along the head traveling direction.

Perpendicular magnetic recording head and perpendicular magnetic recording apparatus

A thin film magnetic head includes a slider and a thin film magnetic transducing element, wherein the slider is provided with an insulating film on a surface of an electric conductive substrate, the thickness of the insulating film being in a range of 0.5 .mu.m-3 .mu.m, and the thin film magnetic transducing element is formed on the insulating film and has a thin film magnetic circuit including a magnetic film and a coil film.

Thin film magnetic head which prevents errors due to electric discharge

In the thin film magnetic transducer element, the front end portions of the upper pole piece and the lower pole piece are partially removed in such a manner that they align non parallel to the gap film on the opposite sides of the gap film. The condition .DELTA.P1&gt;.DELTA.P2 is satisfied when the difference between the maximum pole length P1max and the minimum pole length P1min of the lower pole piece is .DELTA.P1 and the difference between the maximum pole length P2max and the minimum pole length P2min of the upper pole piece is .DELTA.P2. The sub pulse is reduced and so the partial response method can be employed.

Thin film magnetic head and magnetic recording and reproducing apparatus

A thin film magnetic head includes a slider and thin film magnetic transducers, the slider supporting the thin film magnetic transducers. At least one of these thin film magnetic transducers is a magnetoresistive read element. The surface resistivity .rho. of the magnetic film of the magnetic disk is within the range of .rho..gtoreq.0.03.OMEGA..multidot.cm. Electric leak from the thin film magnetic head to the magnetic disk and electric discharge between these two are prevented.

Magnetic disk recording and reproducing apparatus

In the thin film magnetic transducer element, the front end portions of the upper pole piece and the lower pole piece are partially removed in such a manner that they align non parallel to the gap film on he opposite sides of the gap film. The condition .DELTA.P1&gt;.DELTA.P2 is satisfied when the difference between the maximum pole length P1max and the minimum pole length P1min of the lower pole piece is .DELTA.P1 and the difference between the maximum pole length P2max and the minimum pole length P2min of the upper pole piece is .DELTA.P2. The sub pulse is reduced and so the partial response method can be employed.

Thin film magnetic head with an induction type magnetic transducer for

A method of manufacturing a magnetic head apparatus with a magnetoresistive head utilizing the spin valve effect includes a final heat treatment step (S14) of heating the multi-layered spin valve structure (15) with application of a magnetic field in a direction perpendicular to a track width direction of the spin valve magnetoresistive head so that a thin film layer of soft ferromagnetic material (3, 5) to be pinned by a thin film layer of antiferromagnetic material (6) has a uniaxial anisotropy. This final heat treatment step (S14) is executed after all the steps (S1, S3, S5, S7, S8, S9, S11) each of which includes a heat treatment stage executed at a temperature which will vary a uniaxial anisotropy of the pinned thin film layer of soft ferromagnetic material (3,5) are completed.

Manufacturing method of magnetic head apparatus with spin valve effect

Growing community of inventors

Tokyo, Japan

Mikio Matsuzaki