ROLE OF MULTILAYER RELAXATION ON THE MAGNETIC COUPLING OF BILAYER MN ON FE(001)

Interfacial magnetic coupling in a bilayer of Mn on Fe(001) has been d etermined using the all-electron local density full potential lineariz ed augmented plane wave method. Strikingly, the magnetic properties ar e very sensitive to the atomic structure, namely, the multilayer relax ation and the lattice constant in the lateral plane. The magnetic mome nt of the surface Mn appears to favor an antiferromagnetic coupling wi th the underlying Fe substrate, which explains some unusual experiment al results. Since magnetic moments in the two Mn layers are very diffe rent (-2.76 mu(B) for Mn(S) versus 1.09 mu(B) for Mn(I)), a detectable net X-ray magnetic circular dichroism (MCD) signal is predicted for t he antiferromagnetic Mn bilayer.