SPIN POLARIZATION OF MN LAYERS ON FE(001)

The spin polarization of Mn layers for a body-centered-tetragonal structure on Fe(001) is studied using a self-consistent tight-binding real-space model within the unrestricted Hartree-Fock approximation to the Hubbard Hamiltonian. We investigate all the possible magnetic structures of Mn overlayers with respect to the Fe majority-spin direction as a function of the exchange integral J of Mn. For an antiparallel alignment of a Mn monolayer with the ferromagnetic Fe substrate, the Mn magnetic moment exhibits a second-order transition from low spin to high spin in a large interval of the exchange integral J (0.35\ensuremath{\le}J\ensuremath{\le}0.85 eV). The parallel Fe-Mn arrangement exists only for the high spin (Jg0.49 eV), whereas for J\ensuremath{\le}0.49 eV this solution undergoes a first-order transition towards the antiparallel Fe-Mn. Interesting cases are obtained for thicker Mn slabs, which show different solutions for all possible interlayer magnetic arrangements of Mn as a function of the interfacial Fe-Mn spin alignment. The Mn shows a tendency to form a layer-by-layer antiferromagnetic structure coupled ferromagnetically with the ferromagnetic Fe substrate.