Thin film heads with electroplated NiFe magnetic cores are the main parts of hard disk drives. It is generally agreed that a uniform negative magnetostriction magnetic core is essential to minimize stress-induced anisotropy and to obtain a controlled magnetic domain structure. Only weak tensile stress is induced to the core with the traditional process. In this paper, a new process is presented to obtain a more stabilized domain structure core that has a large magnetization distribution from negative to positive. Annealing at the final stage of water fabrication generates a stress distribution from tensile to compressive across the core. Therefore the magnetization distribution is effective to induce stress-induced anisotropy at right angles to the magnetic path. A desired magnetization distribution can be formed by electroplating technologies. Results of the finite elements method show the origin of this stress distribution to be plastic deformation or creep deformation of the core layer on the organic insulation layer.