Toshikazu Nishiyama

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. >

Recording characteristics of metal-in-gap mini composite head

A metal-in-gap mini composite head for rigid disk drives which is composed of CaTiO 3 slider and Fe-Al-Si thin film deposited magnetic core has been developed. Magnetic recording characteristics were studied by comparing with mini monolithic and thin film heads. As a result, metal-in-gap mini composite head displayed excellent recording performance, especially with narrow gap length. High density recording is expected in combination with high H c disks.

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). >

Recording performance of double sided metal-in-gap composite head

The recording performance of the double-sided MIG (metal-in-gap) composite head was studied and compared to that of the ordinary single-sided head. Double-sided MIG heads have better overwrite performance and improved electrical performance, i.e. output amplitude, bit shift. The overwrite value of double-sided MIG heads is 8 dB higher and achieves less than -30 dB for 1800-Oe media at 0.15 mu m of FH and 0.45 mu m of GL. It is thought that this performance is caused by the strong variations of magnetic moment in the vicinity of Fe-Al-Si film deposited on the trailing edge core. >

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. >