Hgst Netherlands, B.v.

Medical University of South Carolina

Samir Y Garzon

John Thomas Contreras

Rehan Ahmed Zakai

Thomas M Crawford

David John Seagle

Bruce Alvin Gurney

Weldon Mark Hanson

Lidu Huang

Remmelt Pit

Saurabh Deoras

Barry C Stipe

Albert John Wallash

Fu-Ying Huang

Patrick Braganca

Jian Zhu

Hamid Balamane

Alexander M Taratorin

Gurinder P Singh

Ikuya Tagawa

Timothy Scott Hughbanks

Keyu Pi

Craig K Yanagisawa

Kenichi Kuramoto

In general, the present disclosure is directed toward a novel hybrid spintronic device for converting chemical absorption into a change in magnetoresistance. This device uses a novel magnetic material which depends on the attachment of an organic structure to a metallic film for its magnetism. Changes in the chemical environment lead to absorption on the surface of this organometallic bilayer and thus modify its magnetic properties. The change in magnetic properties, in turn, leads to a change in the resistance of a magnetoresistive structure or a spin transistor structure, allowing a standard electrical detection of the chemical change in the sensor surface.

Nanoscale spintronic chemical sensor

Disk drives with a Channel System and Write Driver Preamp architecture that dynamically adjusts the write driver's signal wave-shape depending on the write data signal pattern are described. The wave-shape control signal is generated in the Channel and transmitted to the Write Driver Preamp. Embodiments of the invention provide discrete n-level overshoot amplitude control using amplitude-level modulated (AML) signal. One embodiment implements a look-ahead strategy overshoot amplitude control where the overshoot amplitude for each transition depends only on the subsequent (following) bits in the data stream and not on any previously recorded data.

Disk drive with channel and preamp with dynamic write-current control for write head

Interconnect and preamplifier designs are described for use in a disk drive with a common signal return lead system that interconnects a plurality of read transducers (readers) in a slider through the suspension to the preamplifier mounted on the actuator. Preamplifier embodiments have an isolated differential amplifier for each of the plurality of readers in the slider. The set of signal traces in the suspension include a common signal return lead for the plurality of readers in the slider. A preamplifier circuit design according to an embodiment of the invention includes isolated amplifiers for each reader with a separate bias source and power supply isolation elements for both power supply polarities for reduced crosstalk signal and noise between amplifiers.

Disk drive with preamplifier with isolation for multiple readers in a slider with a common return signal

A method, apparatus, and system are provided for implementing a write head device for writer-to-disk contact detection and spacing sensing of recording heads in hard disk drives (HDDs). A write head device, such as a spin-torque oscillator (STO), is provided between a main pole tip and a surrounding magnetic shield of the writer in the recording head. A pair of connections is provided to the magnetic shield and the main pole of the writer, and resistance of the write head device is measured to detect writer to disk spacing and contact.

Implementing write head device for contact detection and spacing sensing

A disk drive dynamic wave shaper (DWS) write driver includes a write current generator that produces a baseline output current for the write current pulses and an overshoot current generator that produces an overshoot current with different values. The overshoot current is added to the baseline current, with the value of the overshoot current amplitude (OSA) being selected in response to the frequency of transitions in the write data signal. The write driver includes logic circuitry that detects the pattern of transitions. Transitions that are immediately followed by a transition will receive a larger-than-nominal OSA1, transitions that are not immediately followed by a transition and that are not preceded by a long sequence of non-transitions will receive a nominal OSA2, and transitions after longer sequences of non-transitions will receive a smaller-than-nominal OSA3.

Magnetic recording disk drive with write current overshoot amplitude (OSA) responsive to data transitions

A method, apparatus, and system are provided for implementing noise based detection of spin-torque oscillator (STO) power on for microwave assisted magnetic recording (MAMR) hard disk drives (HDDs). A low frequency noise generated by a spin-torque oscillator, such as noise in a frequency range between 10 kHz and 100 MHz, is detected. The detected STO noise is compared to a predefined threshold to identify STO power on operation.

Implementing noise based detection of spin torque oscillator power-on in microwave-assisted magnetic recording (MAMR) hard disk drives

The embodiments disclosed generally relate to a read device in a magnetic recording head. The read device uses parametric excitation to injection lock the STO to an external AC signal with a frequency that is two times the resonance frequency, or more. The field from the media acting on the STO causes a change in the phase between the STO output and the external locking signal, which can be monitored using a phase detection circuit. The injection locking improves the STO signal to noise ratio and simplifies the detection circuit.

Phase detection of spin torque oscillator reader excited through parametric excitation

A Dynamic Wave-Shaping (DWS) write driver for use in a preamp in a disk drive is described. The DWS write driver includes a Dynamic Current Booster (DCB) that adds a current component (WDCB) to the standard write driver signal (including overshoot) that is a function of the bit spacing in the write data input waveform supplied to the write driver. The invention allows dynamic control of the bit-pattern dependent overshoot amplitude without requiring significant preamp overhead. Embodiments of the Dynamic Current Booster include a programmable analog feed-forward timer at the preamp level. The boost current amplitude is a function of the time between the transitions that represent bits. In embodiments, the polarity of the boost current WDCB can be programmed to be positive or negative.

Programmable analog feed-forward timer for dynamic wave shaping

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). An amplitude modulated write coil drive current is applied to the write coil in the presence of a DC bias current applied to the STO. The amplitude modulated write coil drive current modulates the STO resistance monitored using an amplifier circuit to identify STO oscillation, used to ensure stable MAMR HDD write operation.

Implementing spin torque oscillator power-on oscillation checker for microwave-assisted magnetic recording hard disk drives

A method, apparatus, and system for implementing calibration of cooling sensitivity of embedded contact sensor (ECS) using thermal fly-height control (TFC) actuations, by subtracting the linear part (TFC heat) from the total measured ECS signal, a profile is provided that is sensitive only to the clearance of the head-disk interface due to cooling effect for hard disk drives.

Implementing calibration of cooling sensitivity of embedded contact sensor (ECS) signal using thermal fly-height control (TFC) actuations

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

Disk drives with sliders including with an impedance compensation network in the signal path for the read sensor are described. The read signal bandwidth at the preamplifier is improved by the impedance compensation network to allow signals in the multi-GHz range from spin torque oscillators as well as tunnel magnetoresistance (TMR) sensors to be used. An embodiment of the invention achieves a signal layout balance by constructing two inductor-capacitor pair structures on the trailing edge of the slider that are integrated into the differential read signal traces. The differential balanced structure helps to suppress external signal interference pick-up from transferring from common-mode pick-up to differential mode.

Disk drive with filter compensation integrated in sliders for high-bandwidth read sensors

Embodiments of the present invention generally relate to a HAMR device having two temperature sensors disposed between a near field transducer (NFT) and a return pole. The two temperature sensors are aligned in a cross-track direction.

Growing community of inventors

Sunnyvale, CA, United States of America

Samir Y Garzon