Headway Technologies, Incorporated

Cisco Technology, Inc.

Fujitsu Corporation

Sap Se

Sichuan University

Jovia, Inc.

Ying Liu

Yuhui Tang

Yue Liu

Jiun-Ting Lee

Wenyu Chen

Kei Hirata

Yiming Wang

Wei-Peng Chen

Yan Wu

Lei Liu

Min Li

Moris Musa Dovek

Shahrokh Sadjadi

Shohei Kawasaki

Junfeng Wang

Qin Luo

Hao Niu

Yoshitaka Sasaki

Hiroyuki Ito

Shigeki Tanemura

Hironori Araki

Kazuki Sato

Tetsuya Roppongi

Pere Monclus

John Ellis

Sushil Kumar Singh

Min He

Shengyuan Wang

Xiaomin Liu

Tetsuhito Shinohara

Yoji Nomura

Valentina Alaria

Alain Truong

Sanghyun Lim

Licheng Zhang

Chien Ming Yueh

Jiun-Tlng Lee

Khuan Tan

Mingyue Zhou

Takeo Kagami

Yimin Qiao

Mei Ki Yeung

Sui Yan Chan

Xiaohui Li

A PMR (perpendicular magnetic recording) write head includes a main write pole (MP) that is surrounded by magnetic shields, including laterally disposed side shields (SS), a trailing shield (TS) and a leading shield (LS). The leading shield includes a leading-edge taper (LET) that conformally abuts a tapered side of the write pole. The leading-edge shield and the leading-edge taper can be independently recessed in a proximal direction away from an air bearing surface (ABS) plane so that one or the other of them is recessed and the other remains coplanar with the ABS, or both are recessed by independent amounts. In another configuration the LS is not planar but has a recessed portion in a center track region and two surrounding regions that are coplanar with the ABS plane.

Perpendicular magnetic recording (PMR) writer with recessed leading shield

A magnetic recording writer is disclosed. In some embodiments, the writer includes a main pole having a front portion and a back portion, a gap layer surround the main pole at the ABS, and a shield structure. The front portion includes a pole tip at an ABS plane, a pole tip thickness in a down-track direction, and curved sidewalls on each side of a center plane that is orthogonal to the ABS and bisects the main pole. The back portion includes first flared sidewalls extending from the curved sidewalls at an angle between 0 and 25 degrees relative to planes parallel to the center plane. The shield structure includes sidewalls having a sidewall portion facing the main pole and formed substantially conformal to the curved sidewalls up to a height of about 30-200 nm where the sidewall portions no longer follow the shape of the main pole.

Magnetic recording writer with improved main pole shape

A method of forming a spin transfer torque reversal assisted magnetic recording (STRAMR) writer is disclosed wherein a spin torque oscillator (STO) has a flux guiding layer (FGL) wherein magnetization flips to a direction substantially opposing the write gap (WG) field when sufficient current (I) density is applied across the STO between a trailing shield and main pole (MP) thereby enhancing the MP write field. The FGL has a center portion with a larger magnetization saturation&#xd7;thickness (MsT) than in FGL outer portions proximate to STO sidewalls. Accordingly, lower Idensity is necessary to provide a given amount of FGL magnetization flipping and there is reduced write bubble fringing compared with writers having a FGL with uniform MsT. Lower MsT is achieved by partially oxidizing FGL outer portions. In some embodiments, there is a gradient in outer FGL portions where MsT increases with increasing distance from FGL sidewalls.

Writer with laterally graded spin layer MsT

A PMR (perpendicular magnetic recording) write head configured for microwave assisted magnetic recording (MAMR) in the form of spin assisted writing (SAW) or spin torque oscillation (STO) includes a spin-torque oscillator (STO) or SAW device and trailing shield formed of high moment magnetic material (HMTS). By patterning the STO or SAW and the HMTS in a simultaneous process the HMTS and the STO or SAW layers are precisely aligned and have very similar cross-track widths. In addition, the write gap at an off-center location has a thickness that is independent from its center-track thickness and the write gap total width can have a flexible range whose minimum value is the same width as the STO or SAW width.

Writer with narrower high moment trailing shield

A PMR (perpendicular magnetic recording) write head configured for thermally assisted magnetic recording (TAMR) and microwave assisted magnetic recording (MAMR) is made adaptive to writing at different frequencies by inserting thin layers of magnetic material into the material filling the side gaps (SG) between the magnetic pole (MP) and the side shields (SS). At high frequencies, the thin magnetic layers saturate and lower the magnetic potential of the bulky side shields.

Writer with adaptive side gap

A spin transfer torque reversal assisted magnetic recording (STRAMR) writer is disclosed wherein a spin torque oscillator has a flux guiding layer (FGL) wherein magnetization flips to a direction substantially opposing the write gap (WG) field when sufficient current (I) density is applied across the STO between a trailing shield and main pole (MP) thereby enhancing the MP write field. A key feature is that the FGL has a center portion with a larger magnetization saturation&#xd7;thickness (MsT) than in FGL outer portions proximate to STO sidewalls. Accordingly, lower Idensity is necessary to provide a given amount of FGL magnetization flipping and there is reduced write bubble fringing compared with writers having a FGL with uniform MsT. Lower MsT is achieved by partially oxidizing FGL outer portions. In some embodiments, there is a gradient in outer FGL portions where MsT increases with increasing distance from FGL sidewalls.

A magnetic head includes a medium facing surface, a main pole, a trailing shield, and a spin torque oscillator. A bottom surface of the trailing shield includes a first portion that includes an end located in the medium facing surface and is in contact with the spin torque oscillator at least in part. An element height that is a dimension of the spin torque oscillator in a direction perpendicular to the medium facing surface and a writer height that is a dimension of the first portion in the direction perpendicular to the medium facing surface are different from each other.

Magnetic head including spin torque oscillator

A PMR (perpendicular magnetic recording) write head configured for microwave assisted magnetic recording (MAMR) includes a spin-torque oscillator (STO) and trailing shield formed of high moment magnetic material (HMTS). By patterning the STO and the HMTS in a simultaneous process the HMTS and the STO layer are precisely aligned and have very similar cross-track widths. In addition, the write gap at an off-center location has a thickness that is independent from its center-track thickness and the write gap total width can have a flexible range whose minimum value is the same width as the STO width.

Writer with HMTS (high moment trailing shield) aligned with spin layer

A preamplifier that that is configured for optimizing the write current waveform to achieve the best areal density capability (ADC) and adjacent track interference (ATI) performance of a magnetic recording disk drive. The preamplifier is configured for providing a magnetic head write current with a main pole relaxation zone for providing a buffer zone for main pole relaxation from saturation state to a remanence state before writing the next bit. The preamplifier is further configured for providing a magnetic head write current with a reference main pole relaxation current located at an end region data of each bit. The length of the reference main pole relaxation current is a function of the bit length, frequency, recording velocity, and writer/media switching speed.

Circuits and methods for optimizing write current waveform for main pole relaxation in perpendicular magnetic recording

This invention discloses a kind of reliable data transmission method based on reliable UDP and fountain code in aeronautical ad hoc networks. This method employs Raptor codes to recover from data loss and avoid retransmission in high loss and high delay channels. A light-weight feedback scheme is designed to provide reliability. An improved SNACK scheme is utilized to deal with the bandwidth asymmetric problem and a novel sliding window mechanism is proposed to avoid TCP's retransmission ambiguity problem and allow for more precise roundtrip-time calculation. A congestion control scheme is deployed to distinguish losses caused by congestion from losses caused by link handoffs to efficiently utilize the available bandwidth. This invention is fully implemented directly on top of UDP in Linux without requiring changes to the underlying network stack implementations. In harsh aeronautical ad hoc network environment, it is suitable for reliable and efficient data transfer service.

Reliable data transmission method based on reliable UDP and fountain code in aeronautical ad hoc networks

A preamplifier has a pre-compensation circuit that optimizes the write current in a low current range of less than 30 mA. The pre-compensation circuit maintains the peak current with a high overshoot current amplitude for achieving an optimized areal density capability to equalize the erase widths for the bit lengths of the encoded data with bit lengths greater than three clock time periods with encoded data with a bit length of the two clock time period. Alternately, the pre-compensation circuit has an overshoot generator that determines the optimum amplitude of the overshoot current for the bit-lengths for the encoded data. An overshoot data synchronizer is connected to a read current preamplifier to receive a pseudorandom read data signal that is applied to the overshoot generator to enable the different overshoot current amplitude depending on the bit length of the encoded data. The pre-compensated data current is transferred to the write head.

Circuits and methods for modifying the write current waveform to improve track density in HDD

A method of forming a spin torque assisted magnetic recording writer is disclosed wherein a spin flipping (STO) device is recessed from an air bearing surface. The STO device has a middle flux guiding layer with a magnetization that flips to a direction anti-parallel to the write gap field when a current of sufficient magnitude is applied from the trailing shield towards the main pole (MP) thereby increasing reluctance in the write gap to enhance writability. A STO stack is deposited and patterned to define a cross-track width on the MP tapered trailing side. Thereafter, the STO stack is patterned to define a STO device with a front side recessed from the air bearing surface, and a backside. A write gap is deposited surrounding the STO device, and has a thickness greater than or &#x2264; to STO thickness to enable design flexibility. Then, first and second trailing shields are formed.

Process of forming a recessed spin flipping element in the write gap

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San Jose, CA, United States of America

Ying Liu