Akio Takada

Dual-stage servo with on-slider PZT microactuator for hard disk drives

A dual-stage servo system with an on-slider piezoelectric (PZT) microactuator is developed for future high-density hard disk drives. The parallel control scheme is used in servo design with considerations over the stroke limitation and the hysteresis of the microactuator. Experimental results on a spin-stand with a laser Doppler vibrometer as the position sensor demonstrate that the system has a servo bandwidth higher than 4 kHz and has disturbance rejection capability up to near 5 kHz.

Advanced vertical MR head

A newly designed vertical magnetoresistive (MR)/inductive head has been developed. In this new head, the read element has the tri-layer structure, in which the insulator layer is sandwiched between the two permalloy layers, and both ends of the elements are filled with the insulator. The sense current lead is connected only to the upper NiFe layer. As a result, not only the sense current density is enlarged but also the film Hk is reduced. The sensor sensitivity is estimated to be 2.5 times as large as that of the conventional vertical MR sensor. The output level of about 700 /spl mu/Vpp is obtained at the read track width of 1.5 /spl mu/m. The D/sub 50/ is at about 5.8 kfc/mm.

Vertical AMR Sensor With New Magnetic Stabilizing Design

We have developed a new vertical anisotropic magnetoresistive (AMR) sensor for narrow track recording. In this design, the lower NiFe layer is deposited on the hard magnetic film. A large exchange coupling occurs between these films. The upper NiFe layer is magnetostatically coupled with the lower NiFe film. As a result, a stable operation is achieved even with a narrow 1 /spl mu/m track width sensor. This head exhibits excellent recording characteristics.

Dual-stage servo with on-slider PZT microactuator for HDD

Summary form only given. A broad bandwidth dual-stage servo system with a novel on-slider PZT microactuator (/spl mu/act) is developed to enable faster system dynamics and to suppress more disturbances for HDD applications.

AMR Head With Newly Designed Vertical MR Sensor For Over 4Gbit/in Density

Takuji Shibata, Akio Takada, Koji Fukumoto, Mmekatsu Fukuyama, Wataru Ishikawa and Yutaka Soda Magnetic Storage Dep., SOW Corp. , 3 4 1 S a k u r a s i , T ~ a j o s h i , ~ y ~ k ~ 9 8 5 , J a p ~ Introduction The h4R head is a key device for the progress of hard disk recording technology. To achieve of the higher areal density, the narrower gap and the narrower track width of MR head are required. The vertical MR head has the severat advantages to this requirement[l-3]. In this study, we tried to achieve an a r d density over 4Gbith2 by the vertical AMR head. In order to keep the high sensitivity and magnetic stabiity at narrow MR track width, the newly designed vertical MR sensor was used as the read element [4]. We discussed the design and recording performance of this head. H The head have the 3-pole structure. The head have been fabricated with the following parameters : 1.5 um read track width, 0.20 um read gap, 1.5 um write track Width, 0.4 um write gap, and 12 coil tums. The read element is the vertical AMR sensor with the structure of Cr-d Magnetic Film/PliFelInsulator/TaMiFeC41. The write pole has a high-Bs magnetic film. The Focused-Ion-Beam etching technique is used to determine the write track width. Fig. 1 shows the micrograph of the head at ABS. Recording Performance Fig.2 shows the roll-off curve of this head. The fly height is 20 nm and the media characteristics are Hp191 Wm, Mrt=13mTum. The measured sense w e n t is 8mA. The output level and PW50 of isolated pulse is about 0.68mVpp and 0.23Oum, respectively. DS0 is around 710Ofc/mm. Fig.3 shows the readback waveform at 7874fdmm. This waveform is very smooth. Fig.4 shows the ofhack profile. The effective read track is 0.97~11. These results suggest that an areal density of over 4Gbh2 is achievable with this head. Result We have developed the AMR head with newly designed vertical MR sensor. The high recording performances of this head were demonstrated. This head is suitable for an areal density of over 4Gb/ii2.