Tdk Corporation

Sae Magnetics (h.k.) Limited

Fujitsu Corporation

Noboru Yamanaka

Yuzuru Iwai

Hiroshi Ikeda

Norikazu Ota

Isamu Sato

Masashi Shiraishi

Makoto Yoshida

Kazumasa Fukuda

Mikio Matsuzaki

Eric Cheuk Wing Leung

Tetsuya Roppongi

Tsutomu Aoyama

Nobuya Oyama

Yoshihiro Kudo

Takuya Adachi

Izumi Nomura

Chris Chiu Ming Leung

Leo Wai Kay Lau

Charles Kin Chiu Wong

Yoshitaka Sasaki

Tomoyuki Sasaki

Shigeki Tanemura

Kosuke Tanaka

Takahiro Yamamoto

Atsushi Iijima

Kei Hirata

Koichi Terunuma

Yoshiaki Tanaka

Hiroshi Kiyono

Keiji Koga

Masashi Sano

Joichiro Ezaki

Tatsushi Shimizu

Katsuki Kurihara

Yosuke Antoku

Taro Oike

Soji Koide

Yasufumi Uno

Yoshiyuki Mizoguchi

Ken-ichi Takano

Keiichi Shibata

Shinji Hiraoka

Tetsuo Miyazaki

Tsutomu Koyanagi

Shunichi Katase

Monjiro Momoi

Hiroki Nakazawa

Akinori Koyama

Man Tse

Mitsuhiro Kitao

Nobuya Ohyama

Susumu Nagatsuka

Chung Keung Ho

Cheung Kwan Lau

Youichi Suzuki

Mikio Ohmori

Takuro Tsuruda

Jun Shouzi

Luke Hung Leung Chung

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

This magnetic recording device is provided with a magnetic write head having a magnetic pole, and a magnetic recording medium having a plurality of data recording blocks. Each of the data recording blocks is formed with a plurality of write tracks, and separated, in a write track width direction, from neighboring one of the data recording blocks with a writing exudation suppression section in between. With this configuration, a magnetic mutual interference of the adjacent data recording blocks at the time of a data rewriting process is avoided even when a mutual interval of the data recording blocks is narrowed, and a good recording state is maintained in each of the data recording blocks. Therefore, it is possible to achieve an improvement in a recording density, while realizing the good and brief data rewriting process for each of the data recording blocks.

Magnetic recording device, magnetic recording method and magnetic recording medium for shingle write scheme

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 microwave assisted magnetic head is formed to include a main pole magnetic layer including a main pole; a shielded magnetic layer including a shielded pole; a recording coil that is formed to generate a writing magnetic field from a tip of the main pole; and a microwave radiation waveguide made of a conductive nonmagnetic material that is disposed in a recording gap, the recording gap being a gap between the main pole and the shielded pole. The main pole magnetic layer and the shielded magnetic layer have an intermediate connection part that connects the layers at a depth-side, and an electrical insulation magnetic film is disposed in the intermediate connection part, and the main pole and the shielded pole are electrically connected with the microwave radiation waveguide that is disposed in the recording gap, which is the gap between the main pole and the shielded pole so that a simple configuration, with a relatively easy and efficient manufacturing process, is realized that overlaps AC magnetic fields in an in-plane direction of a microwave band, which is the same as, or close to, a ferromagnetic resonant frequency of a medium recording layer.

Microwave assisted magnetic head

For obtaining a flying height of a magnetic head from a magnetic disk, the magnetic head being placed in a slider arranged at an interval with the magnetic disk, an initial setting process and a flying height detecting process are performed. In the initial setting process, driving power to a heater is increased gradually, from a state where the heater arranged at a position in proximity to the magnetic head in the slider is not driven, until the magnetic head makes contact with the magnetic disk. Then, in each stage, an electrical resistance value of the sensor arranged at a position in proximity to the magnetic head in the slider, which is increased due to the heat from heater, and either an approach distance of the magnetic head toward the magnetic disk or the flying height of the magnetic head from the magnetic disk are acquired. Then, basic data is prepared by obtaining the relationship between a variation of the electrical resistance value of the sensor and the flying height of the magnetic head from the magnetic disk, which is obtained in each stage or which calculated from the approach distance in each stage. In the flying height detecting process, an electrical resistance value of the sensor is determined, and a variation of the electrical resistance value is calculated from the determined values. Then, the flying height of the magnetic head from the magnetic disk in the state where the electrical resistance value was determined is obtained based on the basic data obtained in the initial setting process, using the calculated variation of the electrical resistance value.

Method of determining flying height of magnetic head

A measurement circuit system of a magnetic field measurement apparatus of the present invention includes an amplifier, a mixer circuit and a band-pass filter that are connected in order on an output end side of a microstrip line or a coplanar wave guide, which is an in-plane high frequency magnetic field intensity measurement element, a frequency immediately before being inputted in the band-pass filter is down-converted by the mixer circuit to a frequency so that a band width of the band-pass filter can be used, the band-pass filter uses a narrow band of &#xb1;0.5-&#xb1;10 KHz (1 KHz-20 KHz as a bandwidth) centering a fundamental frequency selected from 5-20 MHz that is down-converted by the mixer circuit as a center peak passing frequency, and the measurement circuit system is configured to obtain 3 dB or greater of a signal-to-noise ratio (SNR) that is a ratio of S with N; where S represents the reproduction voltage (reproduction output) of the high frequency reproduction signal induced by the in-plane high frequency magnetic field intensity measurement element, and N represents a total noise voltage of a circuit noise including a noise generated by the in-plane high frequency magnetic field intensity measurement element. Therefore, the in-plane high frequency magnetic field that a microwave-assisted magnetic head generates can be measured with high reliability and precision.

Provided is a magnetic reproducing method that enables a thin-film magnetic head including a head element for reading data signals which has a noise in its output due to a low temperature to bring out an excellent read characteristic in which the noise is suppressed even under the use environment with the low temperature. The magnetic reproducing method comprises the steps of: heating a head element for reading data signals which has a noise in its output due to a low temperature; and performing a read operation by using the head element for reading data signals under condition that the head element is increased in temperature.

Magnetic reproducing method for suppressing low temperature noise

Provided is a method for testing a head element that enables proper evaluation of the head element based on a characteristic of the head element under high-temperature and high-stress conditions. The testing method can be performed on a thin-film magnetic head including a head element and a heating element capable of applying a heat and stress to the head element, or performed on a row bar or a substrate wafer on which a plurality of the head elements and a plurality of the heating elements are disposed. The testing method comprises the steps of: causing the heating element to generate heat to apply a heat and stress to the head element; and measuring a characteristic of the head element under the heat and stress to evaluate the head element.

Testing method of head element and magnetic recording and reproducing apparatus capable of head evaluating

The head slider has a plurality of heaters each heating a corresponding region of the ABS, and a sensor detecting collision of the ABS with a projection on a surface of the magnetic disk. Currents supplied to the respective heaters are controlled and produce heats independently of one another. The heats produce projections on the corresponding regions of the ABS, respectively. The ABS with asperity can be planarized through appropriately controlling magnitude of the currents supplied to the heaters. Thus, the variation of a sensor output depending on asperity of the ABS is effectively reduced. Another head slider has a heater locally heating a corresponding region of the ABS. The heater has a structure where a central portion is away from the ABS compared with end portions, or a structure where calorific power of a central portion is smaller than that of each of end portions. Thus, overall projection shape becomes flat.

Head slider, glide height checking apparatus, and glide height checking method

A thin-film magnetic head comprises at least one of a magnetoresistive device for reading and an electromagnetic transducer device for writing, and a heating element provided in the head body part. The heating element has an up portion meandering between an origin and a halfway point and a down portion meandering along the up portion from the halfway point to an end positioned in the vicinity of the origin, and adapted to generate heat when energized.

Thin-film magnetic head, head gimbal assembly, and hard disk drive

A first magnetic film includes a first pole piece, and a second magnetic film includes a second magnetic piece. A gap film is disposed between the first pole piece and the second pole piece. The first magnetic film and the second magnetic film are magnetically joined with each other at a joint as viewed backward from the first pole chip and the second pole chip. A coil film winds vertically around the joint. Third magnetic films are disposed at both sides of the first pole piece or the second pole piece by a given distance.

Thin film magnetic head, magnetic head device and magnetic recording/reproducing device

In a first magnetic film, two notches are formed separately by a given distance, and a first pole piece is located between the notches. The first pole piece includes a uniform width portion. A second magnetic film includes a second pole piece. In the first pole piece, if the height of the uniform width portion is defined by 'TH1', and the depth of the uniform width portion to a top surface from a base plane of the first magnetic film is defined by 'ND1', and the thickness of said gap film is defined by &#x201c;WG&#x201d;, the relations of TH1&#x2267;4WG and ND1&#x2267;4WG are satisfied.

A thin film magnetic head includes a slider, at least one inductive type electromagnetic conversion element and a thermal diffusion film. The inductive type electromagnetic conversion element includes a first magnetic film, a second magnetic film, a gap film, a coil film and an insulating film which are supported by the slider. The coil film is embedded in the insulating film. The thermal diffusion film is made of a metallic film, and disposed in the heat transmission path from the coil film toward the slider.

Thin film magnetic head, magnetic head and magnetic disk driving device

In the thin-film magnetic head of the present invention, the distance to a heat-generating layer is shorter from the end part on the side facing, a recording medium in a magnetoresistive device than from the end part on the side facing the recording medium in an electromagnetic transducer. Therefore, even when the thin-film magnetic head tilts so that its electromagnetic transducer side approaches the recording medium when floating up from the recording medium, the amount of thermal expansion caused by the heat from the heat-generating layer is greater in the magnetoresistive device than in the electromagnetic transducer. This reduces the gap between the magnetoresistive device and the recording medium, whereby a high reproducing output can be obtained.

Thin-film merged magnetic head having a heat-generating layer

Growing community of inventors

Tokyo, Japan

Noboru Yamanaka