Hgst Netherlands, B.v.

Western Digital Technologies, Inc.

Yale University

James William Reiner

Oleksandr Mosendz

Simone Pisana

Franck Rose

Erhard Theodor Schreck

Dieter Klaus Weller

Qing Dai

Sukumar Rajauria

Roger William Wood

Hans Juergen Richter

Michael Paul Salo

Sripathi Vangipuram Canchi

Charles H Ahn

Alexie M Kolpak

Virat Vasav Mehta

Fred J Walker

Sohrab Ismail-Beigi

A heat-assisted magnetic recording (HAMR) disk drive has a disk with at least two independent data layers (RLand RL), each data layer storing an independent data stream. At a high laser power both RLand RLare heated to above their respective Curie temperatures and a first data stream is recorded in both RLand RL. At a lower laser power only upper RLis heated to above its Curie temperature and a second data stream is recorded only in RL. The data layers are separated by a nonmagnetic spacer layer (SL) that prevents lower RLfrom being heated to above its Curie temperature at low laser power. The first and second data streams are typically asynchronous. Recorded data is read back from both data streams simultaneously as a composite readback signal. A joint Viterbi detector detects the asynchronous data streams simultaneously from the composite readback signal.

Heat-assisted magnetic recording (HAMR) disk drive with disk having multiple continuous magnetic recording layers

A procedure for accurately determining thermal flying height control (TFC) touchdown power associated with a head-disk interface (HDI) in a hard disk drive (HDD) involves dithering the spacing corresponding to the HDI by applying an oscillating signal. The touchdown power with the HDI dithering applied is determined and, based on that and the dithering amplitude, the touchdown power without dithering applied, as well as the back-off power, is determinable.

Hard disk drive head-disk interface dithering

Ferroelectric semiconductor devices are provided by including a ferroelectric layer in the device that is made of a material that is not ferroelectric in bulk. Such layers can be disposed at interfaces to promote ferroelectric switching in a semiconductor device. Switching of conduction in the semiconductor is effected by the polarization of a mechanically bi-stable material. This material is not ferroelectric in bulk but can be considered to be when the thickness is sufficiently reduced down to a few atomic layers. Devices including such ferroelectric layers are suitable for various applications, such as transistors and memory cells (both volatile and non-volatile).

Ferroelectric devices including a layer having two or more stable configurations

A method for etching a media is disclosed. A first magnetic layer comprising grains is deposited with a segregant such that a portion of the first segregant covers a top surface of the grains of the first magnetic layer and a second portion of the first segregant separates the grains of the first magnetic layer. The first segregant is etched to remove the portion of the first segregant that covers the top surface of the grains.

Media etch process

A method of making a thermally-assisted recording (TAR) disk includes etching an initial layer of generally spherically shaped FePt grains encapsulated by shells of graphitic carbon layers. The etching partially or completely removes the carbon layers on the tops of the shells, exposing the FePt grains while leaving carbon segregant material between the FePt grains. Additional Fe, Pt and C are then simultaneously deposited. The additional Fe and Pt grow on the exposed FePt grains and increase the vertical height of the grains, resulting in growth of columnar FePt grains. The additional C forms on top of the grains that together with the intergranular carbon form larger carbon shells. The resulting FePt grains thus have a generally columnar shape with perpendicular magnetic anisotropy, rather than a generally spherical shape. Lateral grain isolation is maintained by the carbon segregant remaining between the grains.

Method for making a perpendicular thermally-assisted recording (TAR) magnetic recording disk having a carbon segregant

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Palo Alto, CA, United States of America

James William Reiner