Control of magnetic anisotropy in Fe1-xCox films on vicinal GaAs and Sc1-yEryAs surfaces

We demonstrate that two distinct surface contributions to the magnetocrystalline anisotropy can be used to control the magnetic properties of thin films of bcc Fe1-xCox grown on GaAs (100) and Sc1-yEryAs (100). The bare GaAs (100) surface has twofold symmetry, and Fe1-xCox films grown directly on it show a strong uniaxial magnetic anisotropy. Fourfold symmetry is restored in films grown on interlayers of Sc1-yEryAs, in which the rock-salt structure provides a fourfold symmetric surface. A uniaxial magnetic anisotropy can be induced in this case by miscutting the substrate towards a {111} plane, so that vicinal steps run along a [011] direction. A simple Neel pair-bonding model describes the evolution of the anisotropy with the degree of miscut. For miscut GaAs (100) surfaces without interlayers, both the intrinsic anisotropy originating from the surface bonding and a step-induced term contribute to the total magnetic anisotropy. Depending on the orientation of the miscut, the step contribution can either enhance or partially suppress the intrinsic uniaxial anisotropy. (C) 2001 American Institute of Physics.