The influence of substrate edge stress on magnetoresistive head anisotropy

It is found that the film anisotropy H_k, 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 H _k 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 H_k 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