High speed characteristics of thin film write heads at deep submicron track width

This article presents a micromagnetic study of the dynamic magnetic switchi ng process in the pole tip region of stitched-pole thin film write heads. T he impacts of track width reduction and pole material saturation moment on the high frequency performance of the heads have been investigated. It is f ound that the magnetic switching process of the pole tip region at low reco rding frequencies can be characterized by three stages: the nucleation of a vortex (or vortices), followed by the motion of the vortex (or vortices), and finally the annihilation of the vortex (or vortices). At high frequenci es, however, a residual vortex (or vortices) will always remain in the pole tips, resulting in lower head field amplitude. Frequency roll-off characte ristics of the head field response have been calculated. The roll off is th e result of residual vortex (or vortices), and the vortex moving speed limi ts the operational frequency range of the head. Reducing the track width lo wers the head field 3 dB roll-off frequency. The simulation also finds that the use of 45/55 NiFe, which has significantly higher moment than permallo y, results in higher roll-off frequency as compared to permalloy. (C) 2000 American Institute of Physics. [S0021-8979(00)73108-2].