Epitaxial ferromagnetic metal/GaAs(100) heterostructures

Ferromagnetic bcc-Fe_xCo_1-x(100) films have been successfully grown on GaAs(100) and Sc_yEr_1-yAs(100) by molecular beam epitaxy. X-ray diffraction combined with reflection high energy electron diffraction and low energy electron diffraction patterns revealed the epitaxial orientation of bcc-Fe_xCo _1-x(100)〈010〉∥GaAs(100)〈010〉 and bcc-Fe_xCo_1-x(100) 〈010〉∥Sc_yEr_1-yAs(100)〈010〉. Rutherford backscattering channeling minimum yields, Xmin∼3%, suggest epitaxial films of high crystalline quality. Vibrating sample magnetometry measurements show in-plane uniaxial anisotropy and fourfold in-plane anisotropy for Fe_xCo_1-x grown on GaAs(100) and Sc_yEr_1-yAs(100), respectively. The difference in magnetic anisotropy is interpreted as arising from the Sc_yEr_1-yAs interlayer altering the surface symmetry from twofold symmetry for GaAs(100) to fourfold symmetry. Misoriented substrates were also used to increase the step density in the [Oil] direction, which induced an additional uniaxial anisotropy with a [Oil] easy axis and a [01 1̄] hard axis. This step structure symmetry-induced magnetic anisotropy generated a split field ∼50 Oe in the hard axis for bcc-Fe_xCo_1-x(100) grown on Sc_yEr_1-xAs(100) surfaces.