Magnetism of monoatomic wires on vicinal surfaces

There are three key steps in the development of one-dimensional nanostructures: fabrication, characterization and application. In our contribution we concentrate on the second step, the characterization of the structure and magnetic behavior of monoatomic wires grown on Cu and Ag surfaces with a high density of steps from the theoretical point of view. At first, the geometry of clean Cu(11n) and Cu(10n) vicinal surfaces is optimized by means of ab initio density-functional calculations, and the formation energies of steps along the 〈1 1 0〉 and 〈1 0 0〉 directions are compared with experimental estimates. In the following, the monoatomic Fe wires are placed at various positions onto Cu substrate. The preferential positions of wires are predicted to be the inner corner sites of the steps. From the total energy differences between ferromagnetic and antiferromagnetic configurations the effective intrawire and interwire magnetic coupling constants are estimated. In all investigated cases the resulting magnetic order is ferromagnetic. Finally, the possibility of magnetism in monoatomic wires made of fifth and sixth row elements, which are nonmagnetic in a solid, is explored and discussed. The obtained results are in complete agreement with the known trends that a reduced dimensionality promotes magnetism.