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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.

The control of three-dimensional (3D) geometrical shapes is one of important approaches that contribute the development of new functionalities in material science. We produced 3D Si pyramids with a...

Interfacial spin transport efficiency was studied in a yttrium iron garnet (YIG)/Pt spin-pumping system with different nickelic interlayers. It was found that the magnitude of the spin-pumping signals is sensitive to the chemical composition and crystalline orientation of the nickelic interlayers. As shown by the results obtained, a 2 nm thick metallic Ni interlayer enhances the spin-pumping signal, making it several times larger than that found for a YIG/Pt control sample. The spin-pumping signal around room temperature was found to be enhanced (suppressed) by antiferromagnetic NiO interlayers with perfect [111] orientation (without perfect [111] orientation). Our results confirm that a nickelic interlayer is a possible choice for optimizing interfacial spin transport, which is important for the development of a highly effective spin-based device.

Spin Seebeck effect (SSE) for an yttrium iron garnet (YIG)/nickel oxide (NiO)/platinum (Pt) trilayer device was studied in a wide temperature range. It is found that the SSE signal is nonmonotonic in the temperature domain and shows a maximum around the Neel temperature of the NiO layer, which is similar to the temperature dependence of the spin pumping signal in the same device. This result identified that the thermal-excited incoherent spin currents are also sensitive to the fluctuation of an antiferromagnetic system and can be used to probe the antiferromagnetic phase transition. Furthermore, the antiferromagnetic NiO layer is considered to be valuable for the optimization of spin transport efficiency at YIG/Pt interface, which enhances the SSE signal around room temperature.

Sb deposition and reaction on In/Si(111) were investigated by low-energy electron microscopy, low-energy electron diffraction, synchrotron radiation micro X-ray photoelectron spectroscopy and synchrotron radiation X-ray photo-emission electron microscopy. The Sb deposition process strongly depends on the initial In/Si(111) phases such as √3 × √3, √31 × √31 and 4 × 1. On the In/Si(111) surface where two phases co-exist, the diffusion of In atoms, which are released by the attack of Sb, modifies the deposition and reaction process of Sb. On a mixed In/Si(111) √31 × √31 + 4 × 1 surface, an InSb(111) 2 × 2 structure with elongated domains initially forms along steps. Then In atoms are replaced by Sb atoms and InSb(111) 2 × 2 transforms into Sb/Si(111) 2 × 1 by further reaction with Sb atoms. Here, the existence of the 4 × 1 phase promotes the formation of larger InSb(111) 2 × 2 domains.

The electronic properties of p- and n-type Ba8Ga16Ge30 (BGG) are studied using soft X-ray photoelectron spectroscopy at a high-energy facility. Three bands are resolved in the valence band region. The first band for n-type BGG is sensitive to temperature, while the second band is sensitive for p- type BGG. The change in the ratio of Ba to Ga, from which the carrier type is controlled in this system, modifies the positions of Ga residing at the larger (Ga-CGe)(24) cage. This modi. cation in the host network is responsible for the large differences observed in electronic properties of p- and n-BGGs in this clathrate family. (C) 2009 Elsevier B. V. All rights reserved.

Direct observation of the antiferro (AF) magnetic domain structures of a NiO (0 0 1) surface is found to be possible using a spectroscopy photoelectron low-energy electron microscope (SPELEEM) and a commercial UV Hg excitation light source without using any polarizers. The principle is based on the magnetic linear dichroism (MLD) effect, where different domain contrasts are produced according to the relative angle between the antiferromagnetic axis and the linearly polarized light. The observed AF magnetic domain structures are strongly affected by both bulk AF magnetic domain structures and the stresses induced during the sample cleaving process. Moreover, the AF magnetic domain structures are found to be irreversible when the sample is heated to over its Neel temperature and then cooled. The possibility of imaging AF magnetic domain structures without using synchrotron radiation or a polarizer is attractive.

Sb adsorption processes on In/Si(111) √3 × √3 and √31 × √31 surfaces were investigated in the present work. The dynamic growth behavior was observed with low energy electron microscopy (LEEM), and the local surface structure change was monitored with selected area low energy electron diffraction (LEED). X-ray generated photo emission electron microscopy using synchrotron radiation (SR-XPEEM) was employed in order to see the variation of the chemical state on the surface. On both √3 x √3 and √31 × √31 surfaces, Sb adsorption induces the surface structural change and modifies the chemical interaction of In atoms with Si. In atoms are replaced by impinged Sb atoms, and the discharged In atoms form islands.

Two photoemission electron microscopy (PEEM) systems with different characteristics have been introduced in SPring-8 for a nanotechnology support project. One is an easy to use system (ELMITEC PEEMSPECTOR), which is equipped with an electrostatic lens. The other one is a high end system spectroscopic photoemission and low energy electron microscope (ELMITEC LEEM/PEEM III), which is equipped with a magnetic lens and an energy filter. Test experiments have been done using the PEEM systems and high quality x-rays at SPring-8. In this paper, some experimental results will be presented.

The complex magnetic properties of Fe films epitaxially grown on Cu(0 0 1) have been discussed in relation to their atomic structure. We have studied the Fe films on Cu(0 0 1) by a new direct method for three-dimensional (3D) atomic structure analysis, so-called “stereoscopic photography”. The forward-focusing peaks in the photoelectron angular distribution pattern excited by the circularly polarized light rotate around the light axis in either clockwise or counterclockwise direction depending on the light helicity. By using a display-type spherical mirror analyzer for this phenomenon, we can obtain stereoscopic photographs of atomic structure. The photographs revealed that the iron structure changes from bcc to fcc and almost bcc structure with increasing iron film thickness.

The reaction of dimethylthio- (1) and ethylenedithio-tetrathiafulvalenothioquinone-1,3-dithiolemethides (2) with CuCl2 afforded the corresponding CuCl4 salts, (1)2·CuCl4 and (2)3·CuCl4. For (1)2·CuCl4 the 1 molecules are stacked to form a one-dimensional column, and in each column the neighboring 1 molecules are dimerized. On the other hand, the 2 molecules in (2)3·CuCl4 are stacked one-dimensionally in a triad unit. The CuCl4 ions intervene between the 1- or 2-stacked columns in each case. The electrical resistivities (ρ) for single crystals of (1)2·CuCl4 and (2)3·CuCl4 were 3 × 104 and 0.6 Ω cm at room temperature, respectively. The ρ value of (2)3·CuCl4 increased continuously on cooling, and its activation energy was 0.15 eV, which became gradually smaller with increasing applied pressure. For (1)2·CuCl4 the Cu(II) spins on the CuCl4 ions were only present whilst (2)3·CuCl4 involved both conducting π electrons on the 2-stacked column and localized Cu(II) spins on the CuCl4 ions which did not interact with each other between 300 and ca. 170 K, but below ca. 170 K the conducting π electrons disappeared, presumably as a result of interaction with the localized d spins.

The effect of uniaxial strain to spin-density-wave (SDW) transition in the organic conductor (TMTSF) 2 PF 6 was studied. Strain was applied along the a -, b '- and c * -axes separately. It was found that the SDW transition was most strongly suppressed by the strain along the one-dimensional (1-D) a -axis, and most weakly along the c * -axis, whereas our first expectation was that the most effective strain to the SDW suppression was along the b '-axis, since the interaction along b or b ' is directly associated with the denesting of the quasi-one-dimensional Fermi surface. We discuss why the strain along the axes other than the b '-axis suppress the 1-D nature and therefore SDW.

Photoelectron angular distributions (PEAD) of 2H-NbSe 2 were studied by using a display-type spherical mirror analyzer (DIANA) and circularly polarized light. Forward focusing peaks in a wide acceptance angle of ±60° are clearly observed. The forward focusing peaks in the two PEAD patterns taken with clockwise (cw) and counterclockwise (ccw) circularly polarized light show the three-dimensional atomic arrangements around specific atoms. Three-dimensional atomic arrangements up to at least the third nearest-neighbor layer atoms upon the Nb layer were observed. The characteristic of this experimental method is the full application of the forward focusing peak rotation due to the exciting circularly polarized light.

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]

The temperature–uniaxial pressure (T–P) phase diagram of metal, spin density wave in (TMTSF)2PF6 was apparently quite similar to that of hydrostatic pressure irrespective of the direction of the uniaxial pressure in strain method. However, by the examination of ρa, ρb′ and ρc∗ under three uniaxial pressures, it was found that the anisotropy was similar between hydrostatic and a-axis-uniaxial pressure. The strain along b′ and c∗-axes reduces the anisotropy strongly, i.e. ta/tb′=4.3 with p//c ∗ =10 kbar , for instance, where still spin density wave is present. Although a-compression seems to vary the anisotropy similarly to that of the hydrostatic pressure, the so-called rapid oscillation was not observed under a-compression but under the hydrostatic pressure. This result implies that the effect of a-compression is still different from that of the hydrostatic pressure. We discuss how our result is related with the electron correlation.

We used spectroscopic photoemission and low-energy electron microscopy to investigate the electronic properties of epitaxial few-layer graphene grown on 6H-SiC(0001). Photoelectron emission microscopy (PEEM) images using secondary electrons (SEs) and $\text{C}\text{ }1s$ photoelectrons can discriminate areas with different numbers of graphene layers. The SE emission spectra indicate that the work function increases with the number of graphene layers and that unoccupied states in the few-layer graphene promote SE emission. The $\text{C}\text{ }1s$ PEEM images indicate that the $\text{C}\text{ }1s$ core level shifts to lower binding energies as the number of graphene layers increases, which is consistent with the reported thickness dependence of the Dirac point energy.

Spectroscopic photoemission and low energy electron microscope (SPELEEM) improved its performance after installation at BL17SU/SPring-8, where a multipolarization-mode undulator is employed to produce circularly and linearly polarized soft x rays. This undulator enables us to study the domain structures of ferromagnetic and antiferromagnetic materials by x-ray magnetic circular dichroism and x-ray magnetic linear dichroism. SPELEEM is used to study light elements (C, N, and O), 3d transition-metal elements and 4f rare earth elements, utilizing a wide range of photon energies. The two cylindrical mirrors adopted in front of SPELEEM ensure an illumination area of 14 x 14 microm(2) on the samples. The lateral resolution of a secondary electron photoemission electron microscope image is estimated to be better than 85 nm, whereas the energy resolution of the instrument is better than 0.4 eV.

The anion ordering in (TMTSF) 2 ClO 4 as a function of pressure was examined up to 1.1 GPa by detecting the anomaly in the temperature dependence of resistance under pressure. It turned out that the anion ordering transition was observed up to at least 1.1 GPa by means of an extremely careful control of the rate of slow cooling (< 5 K/h). It is remarkable that the temperature of anion ordering was found to increase up to 41 K, while the strength of the transition determined by the magnitude of resistivity anomaly was reduced.

To clarify the reaction process of Co and Fe with a oxide layer on Si substrates, the annealing processes were analyzed using spectroscopic photoemission and low-energy electron microscopy for a special surface where oxide areas and clean substrate areas (voids) coexist closely in a micrometer-order view. From analyses of XAS spectra and edge jump ratios obtained from the photoemission electron microscopy image, we clarified that Co atoms in the void area remain because of the formation of silicides, but that those on the oxide layer disappear because metallic Co atoms easily diffuse. In contrast, in the case of Fe, we found the formation of various silicides and their gradual diffusion into Si substrate even in the form of silicides.

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.

Examples of the application of photoelectron emission microscopy (PEEM) combined with synchrotron radiation excitation are reviewed. In particular, the combination study of PEEM and X-ray magnetic dichroism spectroscopy is very valuable for magnetic domain imaging. According to the demands of the industry, such as the production of magnetic recording media, the application method becomes very important. In this review, several examples of studies using magnetic circular and/or linear dichroism spectroscopy for ferro- and antiferromagnetic materials are introduced. In addition, pump–probe time-resolved PEEM is introduced. These methods allow us to measure the dynamical motion of micro-magnetic structures in mesoscopic size magnets in response to the field pulse in the sub-nanosecond range.

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.

The anion ordering of (TMTSF) 2 ClO 4 as a function of pressure was examined up to 1.1 GPa by detecting the anomaly in the temperature dependence of resistance under pressure. It turns out that the anion ordering transition is observed up to at least 1.1 GPa by means of an extremely careful control of the rate of slow cooling (< 5 K/h). It is remarkable that the temperature of anion ordering is found to increase up to 41 K, while the strength of the transition observed by the magnitude of resistivity anomaly is reduced.

We investigated the local electronic structures of a molecularly thin ferromagnetic Ti0.8Co0.2O2 nanosheet by means of x-ray nanospectroscopy with spectroscopic photoemission and low energy electron microscopy. By analyzing the Co 2p x-ray absorption and photoemission spectra, the chemical state of doped Co ions in individual Ti0.8Co0.2O2 nanosheet was found to be Co2+ low-spin state, which is consistent with previous magnetization data and first-principles calculation [M. Osada et al., Phys. Rev. B 73, 153301 (2006)]. Furthermore, we employed photoelectron emission microscopy to image the variation in chemical states in Ti0.8Co0.2O2 nanosheets with different stacking structures and clarified the identical Co2+ low-spin state in monolayer and overlapped cases.

Stereoatomscope was used to study the atomic arrangements of intercalation compound Fe1∕3NbS2. The three-dimensional atomic arrangements around different kinds of atoms (Nb and Fe) are visualized by taking the photoelectron angular distribution (PEAD) patterns at clockwise and counterclockwise circularly polarized lights. Atomic distances between the emitters and the scatterers are obtained from the PEAD patterns by measuring the rotation angles of the forward focusing peaks. The applications of stereoatomscope to intercalation compound show the possibility to build an ultimate microscope for scientist.