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 electrical characterisations and electron microscopical structural investigations of the materials used for the heads. We measure quantitatively the difference in stray field widths of heads of different design, the saturation drive current, the three-dimensional magnetic field distribution from electron beam tomography and the flux leakage from secondary gaps in addition to that of the primary gap. The use of functional layers is the gap region reduces the flux leakage from secondary gaps of structural origin. In images obtained from Lorentz microscopy, however, it is still possible to observe and quantity these flux leaks.