INVESTIGATIONS ON THE STRAY-FIELDS OF MAGNETIC READ WRITE HEADS AND THEIR STRUCTURAL REASONS/

A systematic investigation of the magnetic stray-fields of read/write heads is given, which involves electron microscopical magnetic imaging techniques for direct visualisation of the stray-fields as well as el ectrical characterisations and electron microscopical structural inves tigations of the materials used for the heads. We measure quantitative ly the difference in stray field widths of heads of different design, the saturation drive current, the three-dimensional magnetic field dis tribution from electron beam tomography and the flux leakage from seco ndary gaps in addition to that of the primary gap. The use of function al layers in the gap region reduces the flux leakage from secondary ga ps of structural origin. In images obtained from Lorentz microscopy, h owever, it is still possible to observe and quantify these flux leaks.