Ferromagnetic behavior of ultrathin manganese nanosheets

Ferromagnetic behaviour has been observed experimentally for the first time in nanostructured Manganese. Ultrathin ($\sim$ 0.6 nm) Manganese nanosheets have been synthesized inside the two dimensional channels of sol-gel derived Na-4 mica. The magnetic properties of the confined system are measured within 2K-300K temperature range. The confined structure is found to show a ferromagnetic behaviour with a nonzero coercivity value. The coercivity value remains positive throughout the entire temperature range of measurement. The experimental variation of susceptibility as a function of temperature has been satisfactorily explained on the basis of a two dimensional system with a Heisenberg Hamiltonian involving direct exchange interaction.Comment: 13 pages, 9 figure

Structure électronique auto-cohérente d'une surface traitée en liaisons fortes

We develop the self-consistent band structure of a semi-infinite crystal in the tight-binding approximation. We discuss especially the eigenstates of the semi-infinite medium and we determine the electronic density distribution with a Green's function method. We apply the model to the computation of the electronic density distribution of simple cubic crystal with (100) surface, in the non-degenerate case. We discuss especially the dominant role of the dipolar potential. The variations of self-consistent électron charges in T.B. give only a very small contribution to the surface dipolar layer.Nous développons la structure de bandes auto-cohérente d'un cristal semi-infini dans l'approximation des liaisons fortes. Nous discutons notamment les états propres du milieu semi-infini, et déterminons le profil des densités électroniques par la méthode des fonctions de Green. Nous appliquons le modèle au calcul du profil de densité électronique d'un cristal cubique simple (100), dans le cas non dégénéré. Nous discutons notamment du rôle dominant du potentiel dipolaire. Les variations de charge des électrons en liaisons fortes donnent une contribution très faible à la couche dipolaire de surface

North-Holland, Amsterdam MULTI-ADATOM INTERACTIONS ON METAL SURFACES

We present an electronic calculation of interactions between impurities adsorbed on transition metal surfaces. The interaction energies are determined in a self-consistent way within the tight-binding formalism which includes correlation and interatomic repulsion terms. We apply our formalism to Re, and Re, on W(110) and compare the numerical results with recent experiments. 1