C(2X2) ANTIFERROMAGNETIC SUPERSTRUCTURE OF MN OVERLAYERS ON PD(001)

A self-consistent real-space calculation within the d-band tight-bindi ng Hubbard Hamiltonian in the unrestricted Hartree-Fock approximation is carried out to examine the magnetic structure of epitaxial ultrathi n body-centered tetragonal (bct) Mn layers on the surface (001) of Pd for different Mn thicknesses (1 to 5 atomic layers). In plane ferromag netic p(1 X 1) and c(2 X 2) superstructure phases are considered throu ghout this calculation. The c(2 X 2) in plane antiferromagnetic soluti on is found more stable for the monolayer in agreement with ab initio methods. The layer antiferromagnetic solutions are found more stable f or thicker films so that Mn forms ferromagnetic (001) sheets and these sheets align antiferromagnetically.