The growth of magnetic Fe overlayers on sulphur passivated GaAs(100)

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Abstract
This paper describes a new approach for producing epitaxial Fe overlayers on GaAs(100), which prevents the intermixing of the semiconductor elements in the overlayer. This is accomplished by sulphur passivation of the substrate surfaces in an aqueous ammonium sulphide solution prior to Fe deposition. bcc Fe(100) is observed to grow epitaxially on S/GaAs(100) substrates, with most of the S floating out as an ordered overlayer. No evidence of semiconductor interdiffusion into the Fe overlayer is observed. The Fe overlayers are observed to be ferromagnetic, with easy axes along the [010] directions. A uniaxial in-plane anisotropy is observed, in addition to the expected fourfold anisotropy, which is attributed to the bonding geometry at the interface. The saturation magnetization of these overlayers is found to be close to that of bulk Fe.