Magnetic anisotropy of close-packed (111) ultrathin transition-metal films: Role of interlayer packing

The magnetic anisotropy of close-packed (111) ultrathin transition-metal films is studied in the framework of a d-electron tight-binding Hamiltonian which includes hopping, exchange, and spin-orbit interactions on the same electronic level as well as the dipole-dipole energy contributions. The role of the interlayer packing on the magneto-anisotropic behavior is determined by considering fcc- and hcp-like films having up to four layers. Using parameters corresponding to Fe, Co, and Ni we perform self-consistent calculations from which the magnetic anisotropy energy (MAE) is obtained in a nonperturbative fashion as difference between electronic energies. The role of the self-consistent determination of the spin-polarized charge redistribution on the MAE is quantified by comparison with simpler constant-exchange-splitting calculations. The spin and orbital magnetic moments and the MAE are analyzed as a function of him thickness, d-band filling, and d-electron exchange splitting giving emphasis to the differences between fcc- and hcp-like films. Finally, the main limitations of the model are pointed out together with some relevant extensions.