Magnetization profile and magnetocrystalline anisotropy of ferromagnet-semiconductor heterostructure systems - art. no. 104424

Ab initio linear-muffin-tin orbital calculations of the magnetization profi le and the magnetic anisotropy of ferromagnetic-semiconductor (FM/SC) multi layers, bcc Fe/Ge (001) and bcc Fe/GaAs (001), have been carried out to fin d out the microscopic origin of these properties. The electronic magnetic a nisotropy energy (MAE), computed with the force method, was found to favor a magnetization perpendicular to the plane of the layers and to increase wi th the thickness of the ferromagnetic layers. The anisotropy of the energy, i.e., the MAE, as well as the anisotropy of the orbital magnetic moment tu rned out to depend only slightly on the type of semiconductor, Ce or GaAs, and to come mainly from the interface Fe layers. In particular, it was foun d that the relationship between the electronic MAE and the anisotropy of th e orbital moment proposed by van der Laan is very well satisfied in these s ystems. According to that relationship, the magnetic anisotropy of these FM /SC multilayers is mainly due (similar to 80-90%) to a delicate rearrangeme nt of the occupations of certain 3d spin down levels in the interface Fe la yers caused by the change of the magnetization direction.