THE INFLUENCE OF SUBSTRATE EDGE STRESS ON MAGNETORESISTIVE HEAD ANISOTROPY

It is found that the film anisotropy Hk, in an unshielded magnetoresistive (UMR) sensor is changed after the establishment of a tape-bearing surface. It is demonstrated experimentally and by a theoretical 2-D stress/micromagnetic treatment of the UMR head configuration that the undesirable change in Hk is caused by the interaction of an anisotropic stress localized in the vicinity of the lapped tape-bearing surface with the UMR element, which inevitably possesses nonzero magnetostriction. The theory predicts that the change in Hk can be minimized by minimizing the thickness of the SiO2 layers used above and beneath the UMR element. By this means and by minimization of MR element magnetostriction, the intrinsic high sensitivity of the UMR sensor can be preserved in a lapped head.