Non-uniform response in the pole tips of thin film recording heads

A scanning magneto-optic imaging system has been used to observe the dynamic response of the pole tips of thin film recording heads at the air-bearing surface. The magnetic response at the pole faces is non-uniform. The magnetic response is seen to exhibit maximum switching in the region adjacent to the gap, and along the track edges of the trailing pole. The peaked response adjacent to the gap is due to the closing of flux between the pole faces through the path of least reluctance. The response at the edge is due to the additional flux which must enter this pole from the wider trailing pole. In the region adjacent to the gap, variations in the amount of switching are seen on wider track thin film heads. The non-uniform behavior of the poles has been related to written transitions on thin film medium.