Magnetic anisotropies in Co/NI(111) multilayers

The magnetic anisotropy and the saturation magnetization have been investigated in several series of Co/Ni multilayers, with relatively thick Co and Ni layers, grown in ultrahigh vacuum (UHV) and high vacuum (HV) by vapor deposition. The volume and interface contributions to the magnetic anisotropy were determined from magnetization measurements. The Co/Ni interface contribution was found to favor perpendicular anisotropy. A series of 2 Å Co/4 Å Ni multilayers, grown in HV, exhibited an easy axis perpendicular to the layer planes, as evidenced both by polar Kerr rotation and ferromagnetic resonance (FMR) measurements. The first- and second-order anisotropy constants were determined from FMR. Indications were found that the presence of FMR signals in (perpendicular easy) samples with low magnetic sublayer thicknesses depends on the magnitude of the surface anisotropy and on the amplitude of fluctuations in the magnetic layer thicknesses