Thickness-dependent reorientation of the magnetization of Fe monolayers on InP(001)

Fachbereich Physik and Center for Nanointegration (CeNIDE), Universität Duisburg-Essen - Lotharstr. 1, 47048 Duisburg, Germany, EU

Corresponding author: zakeri@mpi-halle.de

Received: 19 October 2007
Accepted: 15 May 2008

Abstract

Fe films were grown by molecular beam epitaxy on {2 4}InP(001) at room temperature in the thickness range of 521 monolayer equivalent (ML). The magnetic anisotropy and magnetization were studied using in situ ferromagnetic resonance and in situ SQUID magnetometry, respectively. For the whole thickness range the magnetization was found to favor an in-plane alignment. The easy axis of magnetization is parallel to the [ ] -direction below 7 ML, which rotates by 45° towards the [100]-direction for thicker Fe layers. The magnetic anisotropy energy of the system has been quantitatively determined as a function of film thickness. The perpendicular magnetic anisotropy is strongly thickness dependent with a large surface-interface contribution which is comparable to that of Fe grown on GaAs. The cubic anisotropy K₄ ≈ 1 10⁴  J/m³, however, is small compared to that of bulk Fe over the whole thickness regime and almost thickness independent. The in-plane uniaxial anisotropy is strongly thickness dependent and originates at the FeInP interface.