Giant enhancement of orbital moments and perpendicular anisotropy in epitaxial Fe/GaAs(100)

The spin and orbital magnetic moments and the perpendicular magnetic anisot ropy of 8 and 33 monolayer epitaxial bcc Fe films grown on GaAs(100)-4 x 6 have been measured using x-ray magnetic circular dichronism and polar magne to-optical Kerr effect. Both the films have approximately the same spin mom ents of about 2.0 mu (B) close to that of the bulk value. The ultrathin fil m shows a giant orbital moment enhancement of about 300% with respect to th e bulk value and a perpendicular interface anisotropy field H-s(Fe-GaAs) of the order of -5 x 10(4) Oe. This may be partially due to an increased degr ee of localization of electronic states at the Fe/GaAs interface associated with the atomic scale interface structure. (C) 2001 American Institute of Physics.