SURFACE MAGNETIC RECONSTRUCTION

The phenomenon of surface magnetic reconstruction (i.e. a different or ientation of the surface spins with respect to the bulk ones) is overv iewed in the framework of mean-field theory as an area-preserving map, where the surfaces are introduced as appropriate boundary conditions. In this way, the nonuniform ground state both of semi-infinite system s and films, can be calculated very rapidly and with a great precision for a variety of magnetic models: (i) a uniaxial antiferromagnet in a n applied magnetic field, a model able to describe Fe/Cr(211) superlat tices with antiferromagnetic interlayer coupling; (ii) a ferromagnet w ith enhanced surface exchange, and with a surface anisotropy favouring the spins to lie perpendicularly to the film surface, while the bulk anisotropy favours in-plane alignment, a model able to describe Gd(000 1)/W(110) films.