Micromagnetic Simulation of Hard Bias Field Effects on Submicron Spin Valve Heads

Abstract

The three-dimensional micromagnetic simulations of submicron spin valve (SV) heads are presented. At such sensor widths, the amplitude of SV head output is reduced. An effective way to improve this reduction is to weaken the longitudinal bias field from permanent magnets. Results of simulations reveal that the magnetizations of the pinned layer near the air bearing surface rotate irregularly below a critical permanent magnet strength at a positive external medium field. This irregular rotation causes hysteresis of transfer curve. The critical permanent magnet strength decreases linearly with an increase in the reciprocal of the square of the sensor width. At the optimum permanent magnet strength, the amplitude of the sensor with 0.3 μm wide is almost the same as that of the sensor with 1.0 μm wide. It is important to evaluate the domain stability of the pinned layer when designing a SV head with submicron sensor widths.