PERPENDICULAR AND INPLANE MAGNETIC-ANISOTROPY IN EPITAXIAL CU NI/CU/SI(111) ULTRATHIN FILMS/

Epitaxial ultrathin Cu/Ni/Cu films with Ni thickness in the range 1.5- 6 nm have been grown by UHV evaporation on the Si(111)-7 x 7 surface. In situ characterization made by low-energy electron diffraction and K ikuchi electron diffraction revealed that both Ni and Cu films glow ep itaxially on Si, with a (111) orientation and with their ((1) over bar 10) axis parallel to the (1 (2) over bar 1) axis of the Si substrate. Magneto-optical Kerr effect measurements performed at room temperatur e have shown that the preferential direction of magnetization lies in the film plane for Ni thickness above 3 nm, while it is perpendicular to the film plane for lower thickness. Brillouin light scattering was then exploited to study the spin-wave dispersion as a function of both the applied magnetic field and the wave vector direction on the surfa ce plane. In order to interpret the Brillouin data, we have used a mac roscopic model which takes into account both dipolar and exchange inte ractions, as well as bulk and interface anisotropy for the (111) plane of a cubic crystal. This enabled us to determine, in addition to the other magnetic parameters, both the in-plane and the out-of-plane anis otropy constants. The observed dependence of these constants on the fi lm thickness indicates that the magnetic anisotropy is mainly of magne toelastic origin. [S0163-1829(97)07838-7].