Atomic arrangement at the GaAs/Fe interface for an As-terminated unreconstructed GaAs (001) face and the epitaxial bcc Fe. The crystallographic orientations are indicated on the left of the figure.
Magnetic hysteresis loops for the Fe film (sample A) observed at a series of temperatures for magnetic field applied along the  crystallographic direction.
Measured temperature dependence of the exchange bias field HE and coercivity field H C of the GaAs/Fe/Au film (sample A). The blocking temperature (TB) is estimated as ∼25 K.
Coordinate system used in the experiments. The applied magnetic field is kept in the plane of the Fe film. Orientations of crystal faces are shown on the sides of the structure.
Magnetic hysteresis loops of the Fe film for the external field H applied at a series of azimuthal angles φH measured from the  direction, as shown in Fig. 4 . The panels on the left show the hysteresis loops observed at 5 K in the ZFC mode. Panels on the right show simulations of the magnetic hysteresis loops for the four angles φH . used in the experiments.
Double hysteresis loops of two GaAs/Fe/Au samples (samples D and E, respectively) measured at 5 K after zero-field cooling (ZFC), indicating the presence of two independent populations of AFM orderings, which pin two populations of FM domains. “S” indicates the point where the first training loop (indicated by black curve) begins.
X-ray reflectivity data for a typical GaAs/Fe/Au multilayer grown on a GaAs (001) substrate. Black curve is experimental; red curve is a computer fit obtained with interfacial layers assumed to be GaAs/Fe2As/Fe/FeO/Au. The thicknesses of the successive layers d obtained from the best fit are as follows: dFe(2)As = 0.73 ± 0.19 nm, dFe = 3.65 ± 0.48 nm, dFeO = 1.4 ± 0.48 nm, and dAu = 1.72 ± 0.36 nm. The data and modeling start at angles just below the critical angle of 0.3°.
Fe L2,3 XAS spectra recorded at room temperature for Fe/GaAs with two different capping layers: The blue curve is for sample A capped by ∼2 nm Au layer, and the red curve is for a sample coated by ∼2 nm Al.
Comparison of magnetic hysteresis loops observed for GaAs/Fe/Au multilayer at (a) 5 K and (b) 25 K; and (c) for a GaAs/Fe/Al multilayer observed at 5 K.
Structural and magnetic parameters of five GaAs/Fe/Au samples studied in the present work. Note that the thicknesses of Fe and Au are estimated from the ion current of the e-beam evaporator, which has a large uncertainty. The thicknesses of the layers are estimated from the growth rate with the error of around 5% for LT-GaAs, and of around 30% for the Fe and Au layers due to possible flux instabilities of the e-beam evaporator.
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