Magnetic anisotropy and magnetostriction in tetragonal and cubic Ni

The magnetic anisotropy energy (MAE) of face-centered-tetragonal (fct) Ni is calculated as a function of the axial c/a ratio. It is shown that the MAE for fct Ni is tremendously enhanced relative to the MAE for fec Ni. The theoretical results are compared with measurements done by means of ferromagnetic resonance on fct Ni films grown on a Cu(001) substrate. Both experiment and theory show that the tetragonal distortion of Ni is crucial for the understanding of the transition to the out-of-plane magnetization for Ni Alms on Cu(001) for thicknesses above similar to 7 atomic monolayers. We have also calculated the magnetostrictive constants for fee Ni and obtained lambda(001) = - 245 x 10(-6) and lambda(111) = - 110 x 10(-6). The relation between lambda(001) and the MAE of fct Ni is investigated by means of magnetoelastic theory as well as by first principles calculations.