Surface morphology, structure and magnetic anisotropy in epitaxial Ni films

Understanding the correlation between film structure and its ferromagnetic properties is very important for applications. To this end, we have investigated epitaxial and smooth Ni films grown on MgO substrates using molecular beam epitaxy (MBE) and dc sputtering. To establish correlation between film morphology and structure with magnetic properties, we have used in situ and ex situ scanning tunneling microscopy (STM) images along with studies on the azimuthal dependence of the magnetization reversal utilizing longitudinal Kerr effect (MOKE). Our MOKE azimuthal studies on annealed MBE-grown (0 0 1) Ni films indicate additional uniaxial anisotropy possibly related to surface nano-patterning, superimposed to the expected four-fold symmetry due to magneto-crystalline anisotropy. This uniaxial anisotropy is absent in non-annealed MBE-grown (0 0 1) Ni films as well as sputtered annealed and non-annealed (0 0 1) Ni films. Conversely, neither annealed MBE-grown nor sputtered (1 1 1) oriented Ni films exhibit surface nano-patterning and their structural and magnetic properties exhibit identical azimuthal dependence. © 2003 Elsevier B.V. All rights reserved.