Understanding the magnetocrystalline anisotropy of iron borate

Magnetocrystalline anisotropy of iron borate is expected to have two contributions: the crystal field one and the dipole-dipole one. The crystal field contribution is calculated through the perturbation theory using the spin Hamiltonian parameters of isolated Fe 3+ ions in diamagnetic gallium borate. The dipole-dipole interaction energy is calculated for two models of extended dipoles having non-negligible size.