Electron probe measurements of field distributions near magnetic recording heads

A transmission electron-microscope selected-area small-angle diffraction technique is used to measure field distributions near ferrite and thin-film magnetic recording heads. The limit of flux detection is the fluxon unit (4 × 10-7G.cm2). For a head height of 30 μm this allows a field precision of 10 Oe for a position precision of 10-5cm. Experimental results from ferrite and thin-film integrated heads are compared with the existing theories. Experiment shows principally that the head profile cannot be considered as a magnetic equipotential and that practical field gradients are lower than those predicted theoretically.