Double magnetization reorientation in epitaxial Cu/Ni/Cu/Si(111) ultra-thin films

We have deposited epitaxial Cu/Ni/Cu sandwiches on the 7 x 7 reconstructed surface of single-crystal (111)-Si substrate with nominal Ni thickness in the range between 10 and 60 Angstrom. Brillouin light scattering from thermally excited spin waves and surface magneto-optic Kerr effect magnetometry show that the preferred direction of the magnetization is perpendicular to the film plane for Ni film thicknesses between 15 and 30 Angstrom, while it is aligned along the film plane for both thicker and thinner films. The observed double reorientation transition is interpreted in terms of a competition between the magnetostatic energy term (shape anisotropy) and both the magnetoelastic and magnetocrystalline anisotropy energy contributions. (C) 1999 Elsevier Science B.V. All rights reserved.