Magnetic Field Dependence of the Magnetocrystalline Anisotropy Energy in hcp Co

Magnetic field dependences of the first and the second uniaxial magnetocrystalline anisotropy constants K u1 and K u2 for hcp Co were obtained at various temperatures between 4.2 and 616 K by using the 90-points least mean square routine. It was found that the contribution of the Fermi level-dependent term to d K u1 /d H is as large as that of the magnetization dependent one, while in the temperature variation of K u1 the Fermi level-dependent term is negligibly small. The temperature variation of K u2 was explained reasonably by a relation derived by considering a changes in the lattice parameter ratio and in the magnetization.