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We study the magnetic structure of perpendicularly magnetized Fe nanowires grown on Au͑788͒ by means of x-ray magnetic circular dichroism. The average size of ferromagnetic domains in the nanowires exponentially decreases with temperature, leading to a steeper decay in magnetization compared to nanoislands of Fe. The temperature dependence of magnetization and domain structures can be well described in terms of local atomic geometry, the number of atomic chains in nanowires, exchange coupling between adjacent spins, and magnetic anisotropy. The nonlinear coverage dependence of the activation energy for the creation of magnetic domains can be explained by overall shape of nanowires, which also implies that the magnetic switching processes are strongly shape dependent at the nanoscale.

We fabricated monatomic Fe wires on vicinal Au(111) surfaces and found that decoration of step edges with Fe adatoms has a significant influence on the behavior of surface state electrons confined between regularly arranged steps. On a surface with Fe monatomic rows, angle-resolved photoemission spectra measured in the direction perpendicular to the steps shows parabolic dispersion, in contrast to one-dimensional quantum-well levels observed on a clean surface. Simple analysis using a one-dimensional Kronig-Penney model reveals potential barrier reduction from 20 to 4.6 eV A, suggesting an attractive nature of the Fe adatoms as scatterers.

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