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Magnetic behavior of Fe nanostructures on a vicinal Au(1 1 1) surface have been investigated by X-ray magnetic circular dichroism (XMCD) measurements. It is found that one-dimensional (1D) Fe chains of 2–3 atomic rows exhibit a ferromagnetic long-range order, and have a larger orbital moment in comparison with stripes and two-dimensional (2D) nanostructures. From the temperature-dependent XMCD measurements, the 1D chains exhibit two phase transitions, which are qualitatively ascribed to a ferromagnetic-to-superparamagnetic and a superparamagnetic-to-paramagnetic phase transions. These results suggest that the magnetism of the 1D chains behaves superparamagnetically.

The electronic structure of nanostructured Co adatoms grown by step decoration of a vicinal Au(1 1 1) surface has been investigated by angle-resolved photoemission spectroscopy (ARPES). With increased Co coverage, the intensity of Au 5d valence bands decreases but their peak positions do not change, suggesting that the mixing between Au 5d and Co 3d bands is negligibly weak. The coverage dependence of ARPES spectra near the Fermi level for Co was compared with bulk photoemission results. At the coverage of 1.28 ML Co, the observed Co 3d bands were identified as the exchange splittings between 3d bands with the similar energy value to the bulk.

The electronic and magnetic nature of Fe monatomic chains and two-dimensional (2D) adlayers grown by step decoration of a vicinal Au (7 8 8) surface has been investigated by angle-resolved photoemission spectroscopy (ARPES). By comparing the coverage dependence of ARPES spectra with bulk photoemission data and band structure calculations, we found that the Fe chains have a low ferromagnetic spin state or a nonmagnetic state, and that the 2D Fe adlayers have a high ferromagnetic spin state similar to the bulk Fe. We have succeeded in mapping out the band dispersion of the Fe chains and the 2D adlayers. The band dispersion of the monatomic chains derived from the ARPES measurement show a strong anisotropic feature reflecting a one-dimensional (1D) character. On the other hand, the ARPES spectra of the 2D adlayers show a finite energy dispersion even in the direction perpendicular to the steps, implying the break down of the 1D character. These results suggest that the electronic structures and the magnetism strongly depend on the dimensionality of the Fe adatom structures.

We have investigated the growth of Fe on Au(4 5 5) and Au(7 8 8) surfaces by scanning tunneling microscopy and examined the electronic structures by angle-resolved photoemission spectroscopy. We found that deposited Fe atoms adsorb at the lower corners of the steps, and form one-dimensional monatomic Fe chains. In addition, Fe deposition has significant influence on the surface potential of the regularly stepped surface. After decorating the step edges with monatomic Fe rows, photoemission spectra measured in the direction perpendicular to the steps show parabolic dispersion and a downward energy shift of the bottom of the surface state band. This result suggests that Fe adatoms at step edges act as attractive scatterers and reduce the step potential barrier height.

Reactivity of water molecules on atomically flat SrTiO 3 (0 0 1) surfaces was investigated with a wide range of the water partial pressure from 10 −4 to 10 3 Pa, by means of scanning probe microscopy (SPM) at room temperature. The reactivity on SrTiO 3 (0 0 1) was observed by monitoring the microscopic friction contrast reflecting SrO and TiO 2 terraces, since the contrast is enhanced by a preferential water reaction on the SrO terraces. The remarkable enhancement of the water reactivity was observed at the partial pressure of 10 3 Pa. A simple estimation revealed that, at this pressure, a condensed water layer is formed on the surface, which was confirmed by the temperature dependence measurements. We conclude that the water reaction on SrTiO 3 (0 0 1) is promoted by the condensation, and propose possible promotion mechanisms relating to the condensed water properties.

The perovskite manganite BiMnO 3 thin film was synthesized by a pulsed laser deposition method on a SrTiO 3 single crystal substrate, and its magnetic properties were investigated. The Curie temperature ( T C ) was about 105 K, consistent with the previous report for BiMnO 3 bulk, prepared under high pressure. However, the saturation magnetic moment was 2.8 μ B , which is smaller than that of the bulk (3.6 μ B ). Effect of Sr substitution for the Bi site was also investigated.

Adsorbed states of π-bonded ethylene at 250 K and ethynyl at 300 K on a Pd(110) surface have been studied by scanning tunneling microscopy (STM). Adsorbed π-bonded ethylene occupies an on-top site of the Pd atom. On the other hand, ethynyl exhibits a pair of depressed spots at both sides, located in the neighbor Pd rows. with a protrusive part between them. At low coverage, π-bonded ethylene molecules form a one-dimensional (3 × 1) structure, which reflects the anisotropic intermolecular interactions, while ethynyl species do not form an ordered structure.