Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Hitachi, Ltd.

Western Digital Technologies, Inc.

Ikuya Tagawa

Yasutaka Nishida

John Thomas Contreras

Yoshihiro Shiroishi

Masato Shiimoto

Hiroyuki Katada

Takeshi Nakagawa

Syuji Nishida

Hiroshi Fukuda

Erhard Theodor Schreck

Barry C Stipe

Takuya Matsumoto

Toshihiko Shimizu

Masafumi Mochizuki

Albert John Wallash

Atsushi Kikugawa

Yoshihisa Kamo

Takehiko Hamaguchi

Tomohiro Okada

Roger William Wood

Junguo Xu

Rehan Ahmed Zakai

Mikito Sugiyama

Isao Nunokawa

Hideaki Maeda

Samir Y Garzon

Jianhua Li

Yuta Udo

Yukiya Shimizu

Tetsuo Yuki

David L Whitaker

Carl Boone

William D Johns

Masaomi Ikeda

Satoshi Tabata

Roger Wood

According to one embodiment, a system includes a head, where the head includes: an optical signal source configured to emit a first optical signal, and a near-field transducer (NFT) configured to focus the first optical signal on a moving ferroelectric storage medium positioned below the head. The system also includes a detector operatively coupled to the head, where the detector is configured to detect a second optical signal generated in and reflected from the ferroelectric storage medium, and where the second optical signal has twice the optical frequency as the first optical signal.

System and method for reading data recorded on ferroelectric storage medium by means of a near-field transducer

A hard-disk drive having a structurally efficient magnetic head slider utilizes a MAMR-based spin torque oscillator (STO) for head-disk contact detection and for flying height sensing. Contact detection and spacing estimation techniques consider the nominal temperature difference, and thus different criteria, between read and write operations.

Hard disk drive with contact detection using a spin torque oscillator

In accordance with one embodiment, a magnetic head includes a main pole configured to emit a recording magnetic field for affecting a magnetic medium, a spin torque oscillator (STO) device in electrical communication with and positioned above the main pole in a track direction, the STO device being configured to generate a high-frequency magnetic field which is superimposed with the recording magnetic field in order to record data to the magnetic medium when current flows to the STO device, and a heat sink positioned near the STO device, the heat sink being configured to reduce a temperature of the STO device when current flows to the STO device. In another embodiment, a method includes forming a heat sink behind a STO device in an element height direction perpendicular to a media facing surface, and/or on both sides of the STO device in a cross-track direction at the media facing surface.

Heat sink for a spin torque oscillator (STO) in microwave assisted magnetic recording (MAMR)

A method, apparatus, and system are provided for implementing a power-on spin-torque oscillator (STO) oscillation checker to monitor STO resistance to identify STO oscillation with microwave assisted magnetic recording (MAMR) hard disk drives (HDDs). A changing bias current is applied to the STO in the presence of constant write drive current. The STO bias current is changed to observe sudden changes in STO resistance monitored using a differentiator circuit to identify STO oscillation, used to ensure stable MAMR HDD write operation.

Implementing spin torque oscillator power-on oscillation checker using ramped STO bias differentiator in microwave-assisted magnetic recording (MAMR) hard disk drives

A magnetic disk drive system configured for shingled magnetic data recording wherein data tracks are recorded in an overlapping fashion on a magnetic media. The disk drive system includes magnetic write heads that are asymmetric so as to have increased writing at one side of the write head. The magnetic disk drive system includes magnetic write heads that are mirror images of one another so that write heads located at opposite surfaces of the magnetic media (e.g. one head facing up and one facing down) end up having preferential writing in the location relative to inner and outer diameters of the magnetic media.

Magnetic data recording system with mirror image asymmetric magnetic write elements

In one embodiment, a system includes a medium, a magnetic head having a write element adapted for writing data to the medium, a MAMR element and/or a TAMR element adapted for assisting recording on the medium, the MAMR element having a microwave-generating portion that receives current for operation thereof, the TAMR element having a localized heat-generating portion that receives current for operation thereof, and a read element adapted for reading data from the medium, a device adapted for measuring environmental conditions relating to the TAMR/MAMR elements and the medium, and a controller adapted for controlling operation of the magnetic head and adjusting operating parameters of the system based on the environmental conditions. The environmental conditions include temperature, a reproduced signal of the read element, and/or clearance between the TAMR/MAMR elements and the medium. The operating parameters include the clearance, amount of current injected to the TAMR/MAMR elements, and/or write current.

Energy-assisted magnetic recording head and systems thereof with environmental conditions control

A magnetic storage apparatus includes a magnetic recording medium, a microwave assisted magnetic recording head at least equipped with a magnetic recording pole that generates a recording magnetic field for writing to the magnetic recording medium and a high-frequency oscillator that generates a high-frequency field, a magnetic reproducing head that reads information from the magnetic recording medium, a signal processing unit that processes a signal written by the magnetic recording head and a signal read by the magnetic reproducing head and a unit that controls clearance between the high-frequency oscillator and the magnetic recording medium. The magnetic storage apparatus has a characteristic that the high-frequency oscillator is not operated except in recording.

Magnetic storage apparatus, head drive controller, and head drive control method

A method, apparatus, and system for implementing spin integrated spin-torque oscillator (STO) with an interface bias control for hard disk drives. Bias circuitry for a spin-torque oscillator (STO) is integrated with a slider for microwave assisted magnetic recording (MAMR). The slider includes read and write transducers and the integrated STO bias circuitry controls a bias potential applied to a write return pole to the write transducer with respect to a disk.

Implementing integrated spin-torque oscillator and interface bias control for hard disk drives

In one embodiment, a magnetic data storage system includes a magnetic disk medium, a microwave-assisted magnetic recording (MAMR) head including a main pole adapted for recording data to the magnetic disk medium having a first recording width, a spin torque oscillator (STO) adapted to apply a high-frequency magnetic field to the magnetic disk medium during a recording operation, wherein the STO is operable or inoperable when in an on or off state, respectively, wherein the main pole has a second recording width when the STO is in the on state, and the second recording width is different from the first recording width, a drive mechanism for passing the magnetic disk medium over the MAMR head, a read head including a magnetoresistance sensor, and a controller adapted for adjusting a shift quantity of the magnetic head depending on whether the STO is in the on or off state.

Write track shift control in shingled-microwave-assisted magnetic recording (MAMR-SMR)

Embodiments of the present invention reduce lowering of a recording current and a recording magnetic field that might occur upon execution of write pre-compensation for compensating the NLTS according to a perpendicular magnetic recording method. According to one embodiment, the recording current overshoot is increased for recording a high NLTS recording data pattern. The read signal quality is improved, thereby a highly reliable magnetic disk can be provided.

Controlling an overshoot amplitude level based on a recording data pattern in a magnetic disk drive

Embodiments of the invention avoid loss of information as recorded, due to an external magnetic field applied. In one embodiment, a pole expanded part prone to occurrence of magnetic saturation is formed so as to prevent magnetic fluxes from being converged at ends of a return pole of a magnetic head.

Thin film magnetic head wherein at least one of a return pole, a first shield, and a second shield has a reverse taper

Embodiments of the invention prevent a decrease in magnetization or demagnetization from occurring to recording magnetization regardless of a direction in which a stray field is applied. In one embodiment, an apparatus for data storage system comprises a head having a magnetic field shield in the vicinity of a main pole, and a cover of the device, using a constituent material with a magnetic field shielding effect, across the cover, or at part thereof. When a stray field in a direction perpendicular to a recording medium is applied, the effect of the magnetic field is alleviated by the magnetic field shield installed in the vicinity of the main pole. In such a case, it need only be sufficient to form the magnetic field shield in a shape optimum for removing the stray field in the perpendicular direction only. When a stray field in a direction horizontal in relation to the recording medium is applied, the magnetic field acting on the recording medium is removed by the cover of the device comprising a magnetic component.

Perpendicular hard disk drive resistive against external magnetic field

Embodiments of the invention improve efficiency in alternating-current demagnetization of a magnetic recording medium. In specific embodiments, magnet fields in a direction slanting to an easy direction of magnetization of recording layer magnetization of a medium in rotation are applied.

Method of demagnetizing magnetic recording medium and apparatus for carrying out same

Embodiments of the invention avoid erasure of recorded data by concentrating stray fields on a magnetic head element. According to one embodiment, in a magnetic storage apparatus using a perpendicular recording medium with a soft magnetic under layer, a soft magnetic shield is provided so as to surround the upper parts and sides of magnetic head elements. A distance between the soft magnetic shield and the medium is shorter than that between the soft magnetic shield and the magnetic head element.

Magnetic head with soft magnetic shield and magnetic storage

Embodiments of the invention provide a countermeasure against spike noise maintaining the data reliability of a magnetic recording layer. In one embodiment, the magnetic domain state right below and around the read head of the soft magnetic layer in the recording medium is locally and temporarily equalized using the write head, whereby, the effect of the spike noise caused by the magnetic domain boundaries (magnetic domain walls) of the soft magnetic layer on the read waveform is prevented. The read retry action of the magnetic hard disk drive is used as the trigger for the timing of the magnetic field application, thereby shortening the time for the magnetic field application.

Growing community of inventors

Hiratsuka, Japan

Ikuya Tagawa