Superlattice symmetry in magnetic multilayer systems

The problem of superlattice symmetry, i.e., the question of periodicity along the growth direction (surface normal) in magnetic multilayer systems, is discussed using discrete Fourier transformations for the anisotropy energy, as well as, for the antiparallel and perpendicular interface exchange coupling. We analyze the system Cu(100)/(Cu3Ni3)(n), where n is the number of repetitions, for the case of free surfaces and surfaces capped semi-infinitely by Cu(100). It will be shown that for some magnetic properties, and only in certain situations, (almost) periodic behavior with respect to n applies, while for other properties an oscillatory behavior is characteristic. Also discussed are implications with respect to typical experimental situations and with respect to traditional supercell approaches.