Tdk Corporation

Nippon Electric Co., Ltd.

Nec Corporation

Nippon Telegraph and Telephone Public Corporation

Hitachi Consumer Electronics Co., Ltd.

Tsutomu Aoyama

Isamu Sato

Yoshikazu Soeno

Hiroshi Ikeda

Masashi Shiraishi

Masanori Sakai

Takashi Kikukawa

Koji Mishima

Tetsuya Roppongi

Kenichi Takano

Haruyuki Morita

Tsuyoshi Umehara

Izumi Nomura

Tatsuya Kato

Yuichi Kubota

Kiyoshi Noguchi

Keiji Koga

Mikio Matsuzaki

Noboru Yamanaka

Susumu Haratani

Akimasa Kaizu

Tetsuhito Shinohara

Kazunori Tamazaki

Kei Hirata

Kazuhiro Hattori

Hidetake Itoh

Yoshinori Ishikawa

Tatsuhiro Kobayashi

Hitoshi Hatate

Takuya Adachi

Akio Watanabe

Yasufumi Takasugi

Yoshimitsu Wada

Takayoshi Kuwajima

Akira Saitoh

Sadaharu Yoneda

Tsunehiko Ikarashi

Tsuneo Kagotani

Keiko Tsuchiya

Junichiro Minowa

Yuko Motegi

Yohji Fujii

Isabelle Louis Joseph Dogue

Kikuo Doi

A magnetic recording device includes a magnetic recording medium, a microwave assisted magnetic head having a main magnetic pole for generating a recording magnetic field, and a spin torque oscillator provided near the main magnetic pole for generating a microwave magnetic field, a recording current supply part for supplying a recording current to recording coils according to recording current waveform data, a drive current supply part for supplying a drive current to the spin torque oscillator, and a drive current control part for controlling supply of the drive current by the drive current supply part based on the data. Taking into consideration as an indicator whether a polarity reversal interval included in the data exceeds a threshold time, the drive current control part controls the drive current supply part so as not to substantially lower the quality of signals recorded on the magnetic recording medium.

Magnetic recording device and magnetic recording method

A magnetic head includes a main magnetic pole used to apply a recording signal magnetic field to a magnetic recording medium and also includes a microwave line through which a microwave alternating current is transferred. The microwave line is connected to the main magnetic pole. The entire end surface of the main magnetic pole is positioned closer to air bearing surface than a connection portion at which the microwave line and main magnetic pole are mutually connected. Therefore, microwave assisted magnetic recording is possible without deteriorating the recording signal magnetic field.

Magnetic head, magnetic head assembly, and magnetic recording and reproducing apparatus

A magnetic recording and reproducing apparatus includes a magnetic recording medium including a recording layer in which at least two magnetic layers are layered on a non-magnetic substrate; and a magnetic head including a main magnetic pole for applying a recording magnetic field in a direction substantially perpendicular to a recording face of the magnetic recording medium and a microwave generating element that generates a microwave magnetic field. The relationship between a thickness Ts of a magnetic layer having a lowest magnetic anisotropy energy among the at least two magnetic layers composing the recording layer of the magnetic recording medium, and a thickness Tt of the recording layer is Ts/Tt&#x2266;0.2. The microwave generating element applies the microwave magnetic field having a width broader than the width of the recording magnetic field generated by the main magnetic pole of the magnetic head to the magnetic recording medium.

Magnetic recording and reproducing apparatus

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 magnetic recording apparatus includes a magnetic recording medium that is provided with a first magnetic layer with magneto crystalline anisotropy energy, a second magnetic layer with magneto crystalline anisotropy energy that is smaller than the magneto crystalline anisotropy energy of the first magnetic layer, and a nonmagnetic metal layer that is positioned between the first magnetic layer and the second magnetic layer and that provides coupling force between the first magnetic layer and the second magnetic layer; and a magnetic head that includes a main pole that applies a recording magnetic field in a direction perpendicular to a film surface of the magnetic recording medium to the magnetic recording medium, and an alternate current (AC) magnetic field generator that applies an AC magnetic field with a frequency of 1-40 GHz to the magnetic recording medium.

Magnetic recording apparatus

A microwave assisted magnetic head includes a main magnetic pole; a trailing shield, a main coil for causing the main magnetic pole to generate a perpendicular recording field, at least one secondary coil for generating an in-plane alternate-current (AC) magnetic field with a frequency in a microwave band from a magnetic recording gap between the main magnetic pole and the trailing shield, nonmagnetic films formed on magnetic recording gap facing surfaces that are defined by the main magnetic pole and the trailing shield, the main magnetic pole and the trailing shield being configured with first soft magnetic films, and second soft magnetic films formed further on the surfaces of the nonmagnetic films. The second soft magnetic films have larger anisotropy fields than the first soft magnetic films have.

Microwave assisted magnetic recording head and magnetic recording method therewith

A magnetic recording method for a recording layer of a magnetic recording medium uses a thin film magnetic head with a sub-coil or a microwave radiator. In the method, a microwave spread spectrum (SS) signal is applied to the sub-coil or the microwave radiator, the microwave SS signal including a ferromagnetic resonant (FMR) frequency of the recording layer as a carrier wave within a band so as to generate an in-plane high-frequency magnetic field so that a magnetization reversal magnetic field Hsw of the recording layer is lowered. The magnetic recording is performed while the magnetization reversal magnetic field Hsw of the recording layer is lowered.

Magnetic recording method using microwave assisted head

An object is to provide a magnetic recording method that demonstrates an additional high assistance effect to magnetic recording by applying an alternate current magnetic field in the in-plane direction to a magnetic recording medium having a large coercive force, and a method of the present invention for magnetic recording using a magnetic recording head to a recording layer of a magnetic recording medium arranged to oppose the magnetic recording head, the magnetic recording head including a main pole, an auxiliary pole, a main coil for generating a perpendicular recording magnetic field to the main pole, and either a sub-coil for generating an in-plane alternate current magnetic field of a microwave band to the main pole or a microwave radiator that is arranged in vicinity of the main pole and that radiates microwaves, the method including: a step for modulating an amplitude of the in-plane alternate current magnetic field by modulating an amplitude of microwave alternating current that is applied to either the sub-coil or the microwave radiator using a modulation signal wave so that a ratio (fc/fm) of a carrier frequency (fc) to a modulation frequency (mf) is from 10 to 40; and a step for performing magnetic recording to the recording layer of the magnetic recording medium by applying the perpendicular recording magnetic field while applying the in-plane alternate current magnetic field with the modulated amplitude to the magnetic recording medium.

Method for magnetic recording using microwave assisted magnetic 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 gap between a main pole and auxiliary pole composing a thin film magnetic head having a microwave assisted function of the present invention is filled with a nonmagnetic dielectric layer to embed a microwave radiator. The nonmagnetic dielectric layer has an inclined surface at a end on a side of an opposing medium surface by which the microwave radiated from the microwave radiator to be bent toward the main pole, whereby the microwave magnetic field generated from the microwave generator can be gathered immediately below the main pole, further improving the microwave assisted effect.

Microwave assisted magnetic head

A microwave assisted magnetic head of the present invention includes: at least two or more auxiliary coils that are arranged in a periphery of a writing main pole; and microwave current supply means that applies microwave currents to the at least two or more auxiliary coils. The at least two or more auxiliary coils respectively include linear body parts linearly arranged on an ABS side, two of the linear body parts of the at least two or more auxiliary coils are arranged in a substantially orthogonal positional relationship, and the microwave current supply means is configured such that the microwave current supply means changes phase differences of the microwave currents applied respectively to the at least two or more auxiliary coils. Therefore, the microwave current can be easily controlled, and thus, a circularly polarized magnetic field with high magnetization inversion efficiency can be generated as an assistance magnetic field.

Microwave assisted magnetic head and magnetic disk device

An optical recording medium which includes three or more information layers and has a higher stack density of information layers than before in the direction of thickness while reducing crosstalk during reproduction, and a method for reading the optical recording medium are provided. The optical recording medium has a three-layer structure which includes a substrate, a first information layer, a first spacer layer, a second information layer, a second spacer layer, a third information layer, and a cover layer thinner than the substrate, with these layers being stacked in that order over the substrate, wherein the following Equation (I) is satisfied:()/&#x2266;0.0032&#x2003;&#x2003;Equation (I)where Ris the reflectivity of the first information layer, Ris the reflectivity of the second information layer, and Ris the reflectivity of the third information layer, and the first spacer layer and the second spacer layer are equal to each other in thickness.

Optical recording medium and method for reproducing the same

In a multi-layer optical disc, having three () or more recording layers thereof, for enabling an easy focus lead-in operation onto a desired recording layer, reflectivity of respective recording layers are so determined that a ratio between the reflectivity of the desired recording layer and the reflectivity of other recording layers is equal or greater than a predetermined value, upon basis of the reflectivity of the other recording layers.

Multilayer optical disc

A recording method suitable for high-density recording is provided to increase the reproduction quality. An optical information recording method is for recording information on an optical recording medium by irradiation of a write pulse of a laser beam to perform reproduction in a production system using a PRML detection scheme. The method includes recording a recording mark by a single write pulse, when the total length of the recording mark to be recorded and a space adjacent to the recording mark is less than a diameter of an effective reproduction spot, being 0.82&#xd7;(&#x3bb;/NA), where &#x3bb; is a wavelength of a reproduction laser beam and NA is a numerical aperture.

Information recording method for optical recording medium and optical recording apparatus

A recording method suitable for high-density recording is provided. When information is recorded on an optical recording medium with irradiation of a write pulse of a laser beam, a length corresponding to 7 T is set to be equal to or less than the spot diameter &#x3bb;/NA of the laser beam where T is one recording clock cycle, &#x3bb; is a wavelength of the laser beam, and NA is a numerical aperture of the objective lens, and a specified mark with a length corresponding to 3 T or more is recorded by a single write pulse.

Recording method for optical recording medium and recording apparatus

Growing community of inventors

Tokyo, Japan

Tsutomu Aoyama