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 th at the MAE for fct Ni is tremendously enhanced relative to the MAE for fec Ni. The theoretical results are compared with measurements done b y means of ferromagnetic resonance on fct Ni films grown on a Cu(001) substrate. Both experiment and theory show that the tetragonal distort ion of Ni is crucial for the understanding of the transition to the ou t-of-plane magnetization for Ni Alms on Cu(001) for thicknesses above similar to 7 atomic monolayers. We have also calculated the magnetostr ictive 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 a s well as by first principles calculations.