Structure-induced magnetic anisotropy in the Fe(110)/Mo(110)/Al2O3(1120)system

Abstract

Fe(110) films were epitaxially grown on sapphire substrates using a Mo(110) buffer layer in an ultrahigh-vacuum molecular-beam epitaxy system. The magnetic properties were examined ex situ by Brillouin light scattering and superconducting quantum interference device magnetometry. To determine the magnetic anisotropy constants the frequency of the Damon-Eshbach [J Phys. Chem. Solids 19, 308 (1961)] surface spin-wave mode was measured as a function of the in-plane angle between the external magnetic field and the Fe [001] crystal axis. The angle-dependent frequency was fitted by a spin-wave model. We found that the easy axis of the cubic magnetocrystalline anisotropy K1 and an additional uniaxial in-plane anisotropy K॥2 are aligned parallel to the in-plane Fe[001] axis for Fe-layer thicknesses from 0.8 to 37 nm, with K1 increasing and K॥2 decreasing with increasing Fe thickness. Possible origins of the observed uniaxial anisotropy are discussed.