ATOMIC-SCALE EVOLUTION OF MAGNETIC ANISOTROPIES

The results of in situ studies of the evolution of the magnetic anisot ropy of Co(100) and Co(110) epitaxial films are discussed. It is shown that uniaxial magnetic anisotropies are the generic signature of symm etry breaking atomic and nm scale structures, e.g. steps, clusters, is lands revealed by scanning tunnelling microscopy (STM) studies, and ar e strongly affected by nonmagnetic overlayers. However, the thickness dependent behaviour is surprisingly complex, with strong changes in an isotropy behaviour occurring with submonolayer depositions of nonmagne tic overlayers, These effects cannot be understood within the usual fr amework of the Neel model but are discussed in terms of several contri buting mechanisms, e.g. strain, dipolar interactions and edge and surf ace anisotropies.