The influence of the textural development on magnetic properties in Co-Cr thin films

Two series Co81Cr19 films (5-980 nm) were chosen to investigate the influence of textural development on magnetic properties. It was demonstrated that both the texture and the magnetic properties strongly depend on the film thickness. In the thickness range from 12 to 980 nm, the coercivity Hc and the orientation ratio ORm of the magnetization are mainly determined by the orientation of a hcp crystallites. In the case of Series B films having thickness range of 46-980 nm, there is a critical thickness, at which the Hc, the orientation ratio ORm and the orientation ratio ORc of the crystallite reach their maximum values and the strain in film is about zero. As the thickness increases, the magnetostriction anisotropy constant gradually changes from the negative to the positive value. The changes of the calculated Hc with the thickness agree much better with experimental value if the magnetostatic interaction is considered in calculation. Without considering the effect of the magnetostatic interaction, the agreement with experiment is poor. This result proves that Hc is mainly controlled by the magnetocrystalline and shape anisotropy, and that the magnetostriction anisotropy exerts a rather small influence on Hc. In the thickness range of 5-12nm, the Co18Cr19 films exhibit an anomalous behaviour, and the observations can be made: (1) Hc is almost independent of the thickness; (2) the squareness ratio Rs increases with increasing thickness, even though the orientation ratio ORc of the crystallite increases with increasing thickness.