Shigekazu Suwabe

MIG mini composite head using single crystal Mn-Zn ferrite

Metal-in-gap (MIG) miniature composite heads whose magnetic circuit is composed of single-crystal Mn-Zn ferrite and sputtered Fe-Al-Si film were prepared. Recording and readback characteristics are compared with those of MIG heads using polycrystalline Mn-Zn ferrite. The relationship between timing asymmetry and bit shift is discussed. Results of magnetic-domain observation by SPIN SEM (scanning electron microscopy) are presented. The output voltage of the single-crystal ferrite MIG head showed a 35% higher value than that of ordinary polycrystalline ferrite. This result is due to the higher readback efficiency, arising from higher permeability of the stressed ferrite. Bit shifts of single-crystal MIG heads are small because of their small timing asymmetry and sharp distribution. Timing asymmetry fluctuations are thought to be due to Barkhausen-like domain-wall pinning through readback. This phenomenon is much less significant in single-crystal ferrites; hence, MIG heads are more suitable for high-density recording than polycrystalline ferrite heads. >

Recording characteristics of MIG heads

The recording characteristics of two different types of metal-in-gap (MIG) heads for rigid disks have been studied. In one the surface facing the recording medium is trapezoidal, while in the other it is straight. Both heads show excellent recording performance, especially for high-H/sub c/ media, compared to non-MIG heads. D/sub 50/ was 30 KFCI with an H/sub c/=1200 Oe disk. The trapezoid type MIG head has 30% higher output voltage than the parallel type, but has a frightening field at the gap, so the effective track width is 2 approximately 3 mu m wider than the optical track width. The parallel type has less fringing field. >

Low inductance double-sided Metal-In-Gap nano composite slider using Fe-Ta-N magnetic film system for 250 Mb/in/sup 2/ recording

We studied some characteristics of a double-sided Metal-In-Gap (DMIG) nano composite slider that has a low inductance structure, Fe-Ta-N type of magnetic film and new geometrical configuration of the gap area. The inductance of this head is approximately 1.0 nH/T/sup 2/. The electrical performance of this head has been evaluated with 5.5 /spl mu/m Track Width and 0.25 /spl mu/m Gap Length for 1800 Oe media. O/W is less than -34 dB at 53 kFCI. Output voltage is more than 150 nVp-p/(um.m/s.turns) at 53 kFCI. This performance is seen to be promising for 250 Mb/in/sup 2/ recording. >

A double sided metal-in-gap head for 150 Mb/in/sup 2/ recording

The performance of double-sided metal-in-gap (D-MIG) composite heads has been evaluated on thin-film media of various coercive forces. The O/W of D-MIG was better than that of the single-sided one because of its higher intensity of the recording magnetic field. The total signal-to-noise ratio (SNR) of a D-MIG on a medium of 1600 Oe was better than that on a medium of 1250 Oe. Consequently, for a D-MIG, predicted recording density extended to 150 Mb/in/sup 2/ on a medium of 1600 Oe with the criterion of O/W(-28 dB) and total SNR (31 dB). >

Bit shift characteristics of MIG head

The bit shift characteristics of MIG (metal-in-gap) heads were compared with those of ferrite and Ni-Fe thin film heads. A small isolated pulsewidth and large S/N (signal/noise) ratio were found to lead to a small bit shift. The bit shifts of MIG heads are smaller than those of non-MIG heads. The bit shifts of composite heads are slightly larger than those of monolithic ones because of the small S/N ratio. Within a 10% ratio, the secondary gap pulse does not have a significant influence on bit shift. >

Growth of 2H-SiC Single Crystals in a C-Li-Si Ternary Melt System

We have achieved the first successful growth of 2H-SiC single crystals using the C-Li-Si melt system. Li-Si melt, whose melting point is lower than 1000 oC, was chosen because the 2H-SiC polytype is more stable at lower temperatures than other polytypes such as 3C-, 4H-, and 6H-SiC. Many hexagonal-shaped crystals of approximately 100 uf06dm in diameter were observed via a scanning electron microscope (SEM). A high resolution transmission electron microscope (HR-TEM) lattice image of the grown crystals showed a periodical structure with A-B stacking along the <0001> direction. These results indicated that the Li-based flux was useful for growing bulk 2H-SiC single crystals.

Magnetic properties of Co-M-C (M=Zr, Hf, Ta) films

The magnetic properties of sputtered Co-M-C (M=Zr, Hf, Ta) films for MIG (metal-in-gap) head applications have been investigated. The Co-Hf-C films had a relatively higher thermal stability of the soft magnetic properties than the other films. After annealing at 700 degrees C, the Co-Hf-C films have high mu (>2000), low H/sub c/( >