Anisotropy of magneto-optical spectra in ultrathin Fe/Au/Fe bilayers

Molecular beam epitaxy grown Au(5 nm)/Fe(1.1 nm)/Au(t)/Fe(1.1 nm)/Au(100 nm)/Fe(1 nm)/MgO(001) structures with t between 1 and 2.5 nm were the subject of optical and magneto-optical (MO) ellipsometry studies at photon energies between 1.5 and 5.4 eV. Both the optical ellipsometry and MO polar Kerr rotation spectra can be explained with a multilayer model based on the bulk optical and MO data for Fe and Au. However, the longitudinal MO Kerr effect spectra depart from the model prediction showing an additional well-resolved structure between 3 and 4 eV. This demonstrates a stronger effect of interfaces on the electronic properties at in-plane magnetization in ultrathin magnetic films. On a macroscopic level the effect can be accounted for by a reduced symmetry of the linear MO tensor. (C) 2002 American Institute of Physics.