Intrinsic magnetic anisotropy versus coupling in arrays of closely spaced circular Fe/GaAs(110) dots, patterned by focused ion beam

We present the results of a detailed magneto-optical Kerr effect and Brillouin light scattering investigation of an epitaxial Fe/GaAs(110) film, 9 nm thick, achieving a quantitative determination of its anisotropy constants. Starting from this film, three different arrays of circular dots with diameter of 200 nm and interdot spacings of 200, 60 and 30 nm, have been produced by focused ion beam patterning. The modification of both the magnetization curves and the spin wave spectrum of the patterned specimens are discussed in terms of structural imperfections, intrinsic magnetocrystalline anisotropy and interdot dipolar coupling.