Crossover from in-plane to perpendicular magnetization in ultrathin Ni/Cu(001) films

Abstract

The easy axis of magnetization in Ni/Cu(001) films exhibits a crossover from in-plane to perpendicular orientation with increasing film thickness. This reorientation at \ensuremath{\approxeq}7 monolayers, observed by ferromagnetic resonance, is substantially different from previous findings for Fe and Co films and can be extrapolated from thin-film data. The artificial lattice structure of Ni on Cu yields within magnetoelasticity theory a volume anisotropy of 29 \ensuremath{\mu}eV/atom agreeing perfectly with experiment. In thinner films the surface anisotropy of -77 \ensuremath{\mu}eV/atom dominates.