Magnetic anisotropy of Co thin films: Playing with the shadowing effect, magnetic field and substrate spinning

The shape and magneto-crystalline anisotropies of 10 nm thick Co sputtered films have shown to be dependent on the oblique deposition angle (alpha i), the angular velocity of the substrate-holder (omega(S)) and the applied magnetic field (H-o) during the deposition. Oblique deposition geometry is natural in our sputtering setup, being a equal to 22 degrees at the edge of 4 in. sample-holder and 32 degrees at its central part. X-ray diffraction analysis has evidenced a (111) texturized fcc structure for all films. Ferromagnetic resonance has shown that samples prepared under H-o of 250 Oe present dominantly the uniaxial H-U field contribution independent of the omega(S)-value, however its magnitude depends on ai. For a non-magnetic holder, Co films show a mixture of twofold (uniaxial) with fourfold (cubic) in-plane magnetic anisotropies. The fourfold contribution is small and it is not influenced by ai or omega(S) within the experimental error, while the dominant twofold contribution, which is governed by the shadowing effect, is reduced for higher omega(S) and for samples positioned at the center of the sample-holder. In addition, the intrinsic isotropic Gilbert damping dominates the relaxation process, which is followed by anisotropic twofold scattering mechanism due to stripes and defects, interestingly not influenced by the substrate rotation during depositions.