Magnetic anisotropy of ultrathin epitaxial Fe films on As-terminated GaAs(001)-(2/spl times/1) surfaces

We quantitatively study the in-plane uniaxial magnetic anisotropy of ultrathin Fe films epitaxially grown on As-terminated GaAs(001)-(2/spl times/1) surfaces in dependence of the film thickness and temperature. It is found that the effective anisotropy constant of the in-plane uniaxial magnetic interface anisotropy first increases with reducing the thickness of the Fe film and then drops to zero. The strength of the in-plane uniaxial magnetic anisotropy is very large with anisotropy fields up to 3 kOe and amounts to 0.2 erg/cm/sup 2/ at T =10 K.