MAGNETIC MULTILAYERS - A DETAILED ANALYSIS OF CONTINUUM VERSUS DISCRETE TREATMENTS

A critical comparison is made between discrete and continuum treatments put forward to determine the magnetic ordering of exchange coupled superlattices. In particular, our interest is focused on the spatial patterns adopted by the coupling between ferromagnetic layers across the nonmagnetic spacers. We find that for values of the spacer electron Fermi wavevector k(F) > pi/a, where a is the lattice parameter, the continuum model breaks down. This gives rise to interesting interference effects, which emerge in the discrete three-dimensional treatment, but which are missed in a continuum pseudo one-dimensional approximation. The experimental evidence is discussed, and an analytic derivation of the critical k(F) value is also given.