R. Schafer et al., GRAIN INFLUENCES ON DOMAINS AND READ-BACK PULSE DISTORTIONS OF FERRITE MIG HEADS, IEEE transactions on magnetics, 29(6), 1993, pp. 3876-3878
Direct observations using micro-ellipsometry, Kerr microscopy, and ele
ctron back-scatter diffraction are made for the first time on individu
al grains in the leading pole-tip region of polycrystalline ferrite MI
G heads intended for narrow track (less than or similar to 10 mu m) da
ta recording. These observations, compared with readback-after-write w
aveforms, indicate that waveform instabilities and asymmetry which can
cause high error rate would be diminished by controlling grain size a
nd orientation in this critical pole-tip region. When large grains (ne
ar the gap) exceed the single domain size (similar or equal to 5 mu m)
but are oriented so their media-facing surface contains an easy-axis
of magnetization, the head produces smaller asymmetry and instability
than when missoriented (large) gap grains or multiple single-domain si
ze grains are present. This indication from a limited sampling of MIG
heads appears consistent with polarized neutron and permeability measu
rements on bulk polycrystalline ferrite and an understanding of surfac
e domain behavior in single crystal ferrite MIG heads.