MAGNETIC-ANISOTROPY OF CLOSE-PACKED (111) ULTRATHIN TRANSITION-METAL FILMS - ROLE OF INTERLAYER PACKING

The magnetic anisotropy of close-packed (111) ultrathin transition-met al films is studied in the framework of a d-electron tight-binding Ham iltonian which includes hopping, exchange, and spin-orbit interactions on the same electronic level as well as the dipole-dipole energy cont ributions. The role of the interlayer packing on the magneto-anisotrop ic behavior is determined by considering fcc- and hcp-like films havin g up to four layers. Using parameters corresponding to Fe, Co, and Ni we perform self-consistent calculations from which the magnetic anisot ropy energy (MAE) is obtained in a nonperturbative fashion as differen ce between electronic energies. The role of the self-consistent determ ination of the spin-polarized charge redistribution on the MAE is quan tified by comparison with simpler constant-exchange-splitting calculat ions. The spin and orbital magnetic moments and the MAE are analyzed a s a function of him thickness, d-band filling, and d-electron exchange splitting giving emphasis to the differences between fcc- and hcp-lik e films. Finally, the main limitations of the model are pointed out to gether with some relevant extensions.