MAGNETIC-ANISOTROPY OF TRANSITION-METAL THIN-FILMS

The magnetic-anisotropy energy (MAE) versus the d-band filling is systematically studied for a number of high-symmetry free-standing transition-metal monolayers and bilayers. We show that a simple tight-binding model combined with the recursion method is very useful in the elucidation of the Complicated MAE problem. A canonical MAE curve is proposed as the simplest one curve consistent with the oscillation theorem and is interpreted in electronic-band-structure terms. Departures from this simple picture found in calculations are discussed in detail based on a symmetry analysis and the generalized theory of Wigner and von Neumann describing the energy-band crossing geometry. Some of our conclusions seem to agree with recent theoretical results and may shed light on the existing controversies regarding the Fe(001) monolayer. Other topics such as the crystal-field splitting, magnetic orbital momentum, the applicability of perturbation theory for MAE evaluation, and the substrate role are touched upon.