An abrupt and large increase in the absolute magnitude of λs in sputtered polycrystalline permalloy (Ni 81Fe19) films for thicknesses below 7 nm was observed. Permalloy films maintain near-zero magnetostriction with film thicknesses above 7 nm. Film surface studies and microstructural characterizations suggest that the magnetostriction observed in this study is possibly due to an altered surface morphology of microstructural origin. This observation appears to be critical from the viewpoint of permalloy-based giant magnetoresistive or spin-valve sensor fabrication where typical permalloy film thicknesses are 3-10 nm. Because thin films with nonzero magnetostriction can induce an undesirable magnetoelastic anisotropy during sensor operation, the control and adjustment of the film composition seems necessary to minimize magnetostriction.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)