Effect of Stress on Magnetic Performance of GMR Head Used for Hard-Disk Drive

The effect of stress on the magnetic performance of a giant magneto-resistive (GMR) head was investigated. The stress in the GMR head consists of residual stress caused by thin-film processing and thermal stress due to heat dissipation in the GMR element. When the difference between the in-plane stresses in the GMR element is large, the output voltage of the head changes; thus, the read characteristic of the hard-disk drive is deteriorated. The stress in the GMR head was analyzed by a three-step finite-element analysis, called zooming FEA, and the magnetic performance of the head under the effect of the stress was calculated. Accordingly, it was found that to reduce the effect of the stress on magnetic performance, the intrinsic stress in the protective layer on the head must be optimized and the temperature rise of the GMR element must be decreased during operation.