Study of SAL-biased MR heads with patterned permanent magnet bias

SAL-biased MR heads with patterned permanent magnet (PM) bias have been studied by micromagnetic modeling. The modeling shows that in shielded MR sensors with narrow track width, the magnetic stray field generated by longitudinally magnetized PM not only produces multi-domain structures in the side-wing regions of MR heads but also degrades the biasing level as well as the sensitivity. These can be improved by either putting transverse exchange bias with FeMn on the SAL or tilting the magnetization angle of PM away from the sense current direction. It is found that proper magnetization angle of PM not only can increase the sensitivity greatly, and but also can eliminate multi-domain structures