In-plane volume and interface magnetic anisotropies in epitaxial Fe films on GaAs(001)

Epitaxial Fe alms were grown on Ga-terminated GaAs(0 0 1) surfaces by molec ular beam epitaxy. Samples with constant Fe thickness as well as step patte rned Fe films have been studied. In-plane magnetic anisotropy energies were determined from hysteresis loops measured by alternating gradient magnetom etry and magneto-optic Kerr effect. A superposition of anisotropies with fo urfold and uniaxial symmetry was found in all films. From the linear variat ion of both contributions with the inverse Fe thickness, the volume and the interface term are determined. The fourfold anisotropy constant of the Fe/ GaAs(0 0 1) interface amounts to -(1.41 +/- 0.2) x 10(-2) erg/cm(2). As a c onsequence, the easy and hard directions of the fourfold term are rotated b y 45 below 6 ML. The uniaxial anisotropy turns out to be a pure interface t erm originating exclusively from the Fe/GaAs interface. The huge anisotropy constant, K-U(Fe/GaAs) = (1.2 +/- 0.2) x 10(-1) erg/cm(2), produces an in- plane anisotropy field up to 2 kOe. (C) 1999 Elsevier Science B.V. All righ ts reserved.