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The creation of three-dimensional (3D) geometrical shapes with atomically ordered surfaces and the investigation of their physical properties are major steps contributing to the development of a new paradigm in surface science. We produced a 3D-patterned Si sample with atomically flat and reconstructed {111} facet surfaces, and investigated its structural and physical properties. To apply the conventional techniques in surface science to 3D samples with various oriented surfaces, instead of two-dimensional planar samples, an appropriate relationship between the crystallographic surface ordering on the 3D-architected surfaces and the angle-resolved photoelectron spectroscopy (ARPES) setup considering the configuration in 3D space is indispensable. The distinctive and complex low-energy electron diffraction (LEED) patterns reflecting the 3D-arranged facet surfaces showed the realization of atomically reconstructed facet surfaces on 3D-patterned Si. Surface states of the 3D-patterned Si{111} surfaces are mapped by ARPES by considering the 3D geometrical relationship. The selection of the appropriate alignment of the incident electron beam (light) for the target surfaces allows the clear observation of the band dispersion from the produced {111}7×7 facet surfaces in 3D space. Our demonstration of accessibility of ARPES technique could provide useful guidelines for new methodologies, giving a fundamental understanding of 3D-shape-induced novel functionalities.

Dynamic surface structures of Tin (Sn) on Si(111) were studied by using low energy electron microscope (LEEM). Different from the reported phase diagram, (√3 × √3)-R 30° Sn structure is found existing only in a narrow Sn film thickness range and disappearing quickly over 1/3 monolayer (ML) Sn deposition at substrate temperature of 400°C. Sn islands, which are different from the S-K mode growth, begin to grow from around 1/5 ML along steps or domain boundaries. The models of Sn growth on Si(111) are proposed. [DOI: 10.1380/ejssnt.2005.350]

Both ${\mathrm{Ba}}_{24}{\mathrm{Si}}_{100}$ and ${\mathrm{Ba}}_{24}{\mathrm{Ge}}_{100}$ with crystallographically identical structure are found to be superconducting at 1.4 and 0.27 K, respectively. Physical properties of this superconductor ${\mathrm{Ba}}_{24}{\mathrm{Si}}_{100}$ are studied by electric transport, specific heat capacity, and magnetic susceptibility measurements. The density of states at the Fermi level ${N}_{{E}_{F}}=0.148$ states ${\mathrm{eV}}^{\ensuremath{-}1}\phantom{\rule{0.3em}{0ex}}{(\mathrm{Si}\phantom{\rule{0.3em}{0ex}}\text{atom})}^{\ensuremath{-}1}$ and a distinct jump of ${C}_{p}$ at the superconducting transition temperature $\ensuremath{\Delta}{C}_{p}=0.272\phantom{\rule{0.3em}{0ex}}\mathrm{J}\phantom{\rule{0.2em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}\phantom{\rule{0.2em}{0ex}}{\mathrm{mol}}^{\ensuremath{-}1}$ are obtained. An exponential fit of ${C}_{p}$ below the superconducting states gives an energy gap $2\ensuremath{\Delta}=0.423\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ and shows that this is a superconductor having $s$-wave character or isotropic energy gap. On the basis of our experimental data other important physical parameters are also derived.

The domain structure of antiferromagnetic (AFM) NiO(100) has been investigated by nonmagnetic x-ray linear dichroism (XLD) at the O $K$ edge using photoemission electron microscopy and linearly polarized x-ray light. The evolution of XLD image contrast as the function of the angle between the crystal orientation and the incident $s$- or $p$-polarized light is clearly observed. The angular dependence of the XLD contrast is in good agreement with the calculated x-ray absorption cross section of O 1$s$ to 2$p$ orbital that is deformed anisotropically by the strong hybridization with Ni 3$d$ orbitals. This agreement strongly supports the conclusion that the observed XLD contrast reflects the twin-domain ($T$-domain) structure of the NiO crystal. By comparing the experimental data with the calculation, it is possible to assign each domain contrast to a specific $T$-domain in the quantitative manner. The proposed simple and clear way of $T$-domain assignment will be useful for investigating the magnetic domain structures of NiO and other oxide AFM materials such as FeO, CoO, and CuO, and will be important for understanding the magnetic properties of AFM materials, such as the exchange bias effect.