Field annealing effect on magnetostriction and sensitivity of the ferromagnetic Fe60Co18Ga22/Si(1Â 0Â 0) film

As-deposit (AD) and field-anneal (FA) Fe60Co18Ga22 films have been made. We found that after FA treatment, both the macro-stress and saturation magnetostriction in the film increase greatly. Also, after FA treatment, the tetragonal L12 phase shows up, and coexists within the original two-phase (A2 + D03) field. In agreement with the theory, the occurrence of large stress and magnetostriction is related to the magnetic-field-induced flip of the tetragonal axis of the L12 phase crystal by FA. As a low-field sensor, FA could enhance the sensitivity of the Fe60Co18Ga22 film element up to 18.9 ppm/Oe.