Magnetic switching characteristics at the pole tips of thin film heads

The magnetic response of a thin film inductive magnetic recording head was studied using a high resolution scanning magnetooptic photometer system. The photometer system has a frequency response of 50 MHz and a measuring spot size as small as 0.5 μm in diameter. The position of the sample in relation to the objective lens was determined with precision stepping motors controlled by a computer. This arrangement provides a smooth scan with sub-micron resolution. By scanning across the pole tips of a thin film recording head as the head is being driven with its coils, the profile of the switching magnetization in the poles can be determined. Eddy current effects through the pole tips have been observed. The measured response has been compared to a finite element computer simulation of the head taking into account eddy currents.