Spin polarization at the Fe/V interface

The local magnetic moments and magnetic order are investigated at the Fe/V interface of thin ${\mathrm{Fe}}_3$/${\mathrm{V}}_{\mathit{n}}$ films and thin V films adsorbed on Fe substrate. Different crystallographic directions (001), (101), (111), and a two-atom-width and monoatomic-height-per-step stepped surface [corresponding to the vicinal (103) surface] are considered. We calculate the spin-polarized electronic-charge distribution of these systems as a function of the exchange integral ${\mathit{J}}_{\mathrm{V}}$ of vanadium in the range 0≤${\mathit{J}}_{\mathrm{V}}$≤0.8 eV using a self-consistent tight-binding real-space model within the unrestricted Hartree-Fock approximation to the Hubbard Hamiltonian. For (001), (011), and (111) crystallographic faces, the spin polarization of the V atoms at the Fe/V interface is nonzero for any ${\mathit{J}}_{\mathrm{V}}$ value, with antiferromagnetic coupling between the Fe and V interface atoms. Due to the hybridization between V and Fe orbitals, the spin polarization at the interface tends to increase in V with respect to the corresponding pure-V system, whereas the opposite happens in Fe, resulting in a magnetic moment induced at the interface V atoms by the Fe substrate. This effect is less pronounced in the (101) orientation. Both results can be qualitatively explained by considering two facts: (a) the stronger electron-electron interaction of Fe with respect to V; (b) Fe atoms at the interface have fewer V atoms at nearest-neighbor positions for the (101) orientation than for the (001) orientation. In the case of V adsorbed on the (103) vicinal surface of Fe, the internal and external V atoms at the surface layer of each step are coupled antiferromagnetically. For this particular case, there is a strong competition between the tendencies of V to couple antiferromagnetically with the ferromagnetic Fe substrate and with its V nearest neighbors.