Grain influences on domains and read-back pulse distortions of ferrite mig heads

Abstract

Direct observations using micro-ellipsometry, Kerr microscopy, and electron back-scatter diffraction are made for the first time on individual grains in the leading pole-tip region of polycrystalline ferrite MIG heads intended for narrow track (≲10μm) data recording. These observations, compared with readback-after-write waveforms, indicate that waveform instabilities and asymmetry which can cause high error rate would be diminished by controlling grain size and orientation in this critical pole-tip region. When large grains (near the gap) exceed the single domain size (⋍5μm) 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 size grains are present. This indication from a limited sampling of MIG heads appears consistent with polarized neutron and permeability measurements on bulk polycrystalline ferrite and an understanding of surface domain behavior in single-crystal ferrite MIG heads. © 1993 IEEE