Shape induced in-plane magnetic anisotropy rorientation in epitaxial hexagonal close packed cobalt dots

The in-plane magnetic easy-axis reorientation was investigated for the arra ys of (10.0) hcp Co rectangular dots 0.2 mu m in width with a variable leng th from 3 to 5 mu m perpendicular to the c axis. In the system, the magnitu de of the shape anisotropy contribution is determined by a lateral aspect r atio of the dot, while the magnetocrystalline anisotropy contribution is te mperature dependent. The torque curves for the dot arrays exhibited a chara cteristic fourfold symmetry due to the easy-axis reorientation. The reorien tation angle from the initial easy axis was found to be dependent on the va lue of in-plane demagnetization factors as well as the temperature variable first and second magnetocrystalline anisotropy constants. The experimental results are in good agreement with the calculated effective magnetic aniso tropy. (C) 2000 American Institute of Physics. [S0021-8979(00)37708-8].