Yoshiaki Sonobe

6468670, Oct 22, 2002

Jan 19, 2000

09/487234

Yoshihiro Ikeda - San Jose CA
Manfred Ernst Schabes - San Jose CA
Yoshiaki Sonobe - San Jose CA
Kentaro Takano - San Jose CA
Dieter Klaus Weller - San Jose CA

International Business Machines Corporation - Armonk NY

G11B 566

428611, 428 653, 428 657, 428669, 428670, 428694 TM, 428694 TS

A composite perpendicular magnetic recording disk has two distinct magnetic layers formed on the disk substrate, each with strong perpendicular magnetic anisotropy, that are strongly exchange coupled perpendicularly to each other across their interface. The first layer is a CoCr granular layer formed on a growth-enhancing sublayer, such as titanium, so as to have strong perpendicular magnetic anisotropy. The second layer is a continuous layer, preferably a continuous multilayer of Co/Pt or Co/Pd palladium formed on top of the granular layer. An interface layer, such as a layer of platinum or palladium, depending on whether the top multilayer is Co/Pt or Co/Pd, respectively, may be located between the two layers to enhance the growth of the continuous multilayer.

6537638, Mar 25, 2003

Dec 13, 2000

09/681056

Hoa Do - Fremont CA
Yoshihiro Ikeda - San Jose CA
Yoshiaki Sonobe - San Jose CA
Kentaro Takano - San Jose CA

International Business Machines Corporation - Armonk NY

G11B 566

428 653, 428 656, 428694 TS, 428694 TM, 428900

A perpendicular magnetic recording disk has an underlayer structure that causes the magnetic layer to have perpendicular magnetic anisotropy and high signal-to-noise ratio (SNR). The underlayer structure comprises a B2 type body-centered-cubic (BCC) material, such as the binary alloys NiAl, RuAl and RuTi, as an underlayer, and a Ti or TiCr alloy sublayer formed directly on the underlayer. The magnetic layer, such as a CoCrPt alloy, is deposited directly on the sublayer. The magnetic layer has perpendicular magnetic anisotropy due to the sublayer yet excellent SNR because of the smaller grain size of the sublayer material formed directly on the B2 type underlayer.

6687067, Feb 3, 2004

Mar 9, 2001

09/802636

Francesco Brianti - San Jose CA
Bertrand Gabillard - Paris, FR
Martin Aureliano Hassner - Palo Alto CA
Manfred Ernst Schabes - San Jose CA
Yoshiaki Sonobe - San Jose CA
Barry Marshall Trager - Yorktown Heights NY

International Business Machines Corporation - Armonk NY

G11B 509

360 46, 360 67, 360 65, 360 69

A Hilbert transform is used to process perpendicular magnetic recording signals from both single layer and dual layer disks to produce a complex analytic signal. This complex analytic signal is used to derive angles of magnetization, which depend on the distance between recorded magnetic transitions and consequently which can be used in error estimation. Moreover, the Hilbert transform in cooperation with an equalizer FIR optimizes transformation of the signal such that conventional longitudinal recording processing methods can subsequently be used to process the signal that is read back from the magnetic recording medium.