Simulation of magnetization distribution in magnetoresistive film under a longitudinal bias field

Abstract

The effects of longitudinal bias field, used for domain control on the magnetization distribution in a magnetoresistive (MR) film, have been investigated by computer simulation. The longitudinal bias field was generated by an exchange-coupled antiferromagnetic or permanent magnetic film formed on the MR film outside the sensing region. It was assumed that the magnetization in the part of the MR film on which the bias-generating films were formed was fixed along the easy axis. The spatial sensitivity of the MR film along the track width was evaluated by calculating the dependence of the resistance change on the position of a narrow track recording medium. It was found that the resistance change in the MR film with the anti-ferromagnetic film was roughly twice as large as the change in the film with the permanent magnetic film. The asymmetric sensitivity profile with respect to reflection about the track width mid-plane was also obtained. The asymmetry in the track sensitivity profile was found to be caused by three factors: asymmetric magnetization distribution about the track width mid-plane due to the transverse bias field, the difference in angular changes in the magnetization direction in the left and right regions facing the recording medium, and anisotropic flux propagation in the MR film.

Numerical analysis of sensitivity distribution for MR strips stabilized by permanent magnet films

“…Ishikawa et a1. [5] demonstrated that the leakage field of the domain control films suppressed magnetization rotation in the MR films especially at the track edges and hence formed lower sensitivity region at the track edges and decreased the effective track width.…”

“…In this work, we apply micromagnetic calculations [5]. [7] to the unshielded soft adjacent layer (SAL) [6] bias MR strip stabilized by the permanent magnet films, and numerically analyzed the effects of the leakage field on the bias profile.…”