Influence of spacer thickness reduction on bias level and peak asymmetry in SAL-biased MR heads

The peak asymmetry relates to the bias level of a magnetoresistive sensor. However, the peak asymmetry is affected not only by bias level but also by the shape of the transfer curve. Measured MR bias level and peak asymmetry are less sensitive to bias current variation when the spacer thickness between MR and SAL is reduced. The numerical calculation shows that the magnetization distribution in the MR film becomes more uniform when a thinner spacer is used, indicating stronger magnetostatic coupling between layers. Calculated results of the peak asymmetry and the bias level versus bias current are in good agreement with the experimental data.