NONCOLLINEAR ORDER CONTRIBUTION TO THE EXCHANGE COUPLING IN FE CR(001) SUPERLATTICES/

By means of a d-band tight-binding Hamiltonian, we calculate the nonco llinear distribution of magnetic moments in Fe/Cr superlattices, as a function of the relative orientation Delta phi of the magnetic moments at the center of two adjacent Fe layers. All magnetic moments are com puted self-consistently in both magnitude and angle. We find that for thick layers of a Cr spacer, the total energy varies parabolically as a function of Delta phi, in accordance with the phenomenological proxi mity magnetism model proposed by Slonczewski. However, this model is n ot entirely satisfied for small Cr thicknesses because of the assumpti ons made in it.