Interlayer exchange coupling in Fe/SiFe/Fe sandwiches

The interlayer exchange coupling in Fe/c-FeSi/Fe has been theoretically inv estigated in the framework of the ab initio tight-binding linear-muffin-tin -orbitals method. The system is modeled according to recent structural anal ysis performed with LEED techniques, which show that the Si spacer transfor ms into an ordered Si0.5Fe0.5 alloy in the CsCl structure (c-FeSi). We obta in antiferromagnetic coupling between the Fe layers for spacer thicknesses smaller than about 17 Angstrom with non-monotonous decaying behavior. The d ensity of states of the FeSi spacer at the Fermi level is very small, and d isplays a sharp peak at about 0.5 eV above the Fermi level. Our results are discussed and compared with available experimental data. (C) 2001 Elsevier Science B.V. All rights reserved.