Elsevier Acta Medica Okayama 0040-6090 698 2020 Strain effects on spinodal decomposition in TiO2-VO(2)films on TiO2(100) substrates 137854 EN Yuji Muraoka Research Institute for Interdisciplinary Science (RIIS), Okayama University Fumiya Yoshii Graduate School of Natural Science and Technology, Okayama University Takahiro Fukuda Graduate School of Natural Science and Technology, Okayama University Yuji Manabe Graduate School of Natural Science and Technology, Okayama University Mikiko Yasuno Graduate School of Natural Science and Technology, Okayama University Yoshito Takemoto Graduate School of Natural Science and Technology, Okayama University Kensei Terashima Research Institute for Interdisciplinary Science, Okayama University Takanori Wakita Research Institute for Interdisciplinary Science (RIIS), Okayama University Takayoshi Yokoya We investigate the influence of lattice strain in the c-axis direction on spinodal decomposition in rutile TiO2-VO2 films on TiO2(100) substrates. The [100]-oriented Ti0.4V0.6O2 (TVO) solid-solution films are fabricated on rutile TiO2(100) substrates using a pulsed laser deposition with a KrF excimer laser, and are annealed inside the spinodal region. X-ray diffraction and scanning transmission electron microscopy are employed for characterization. Consequently, the in-plane tensile strain in the c-axis direction promotes the Ti-V interdiffusion in TVO/TiO2(100) under thermal annealing. In contrast, relaxation of the tensile strain results in the occurrence of spinodal decomposition along the c-axis direction in the film. These results indicate that the relaxation of the tensile strain in the c-axis direction is critically important for enabling spinodal decomposition in TVO/TiO2(100). Our work helps deepen the understanding of spinodal decomposition in the TVO film and provides information on achieving novel nanostructures via spinodal decomposition in TVO/TiO2(100). No potential conflict of interest relevant to this article was reported.

Nature Publishing Group Acta Medica Okayama 2045-2322 9 2019 Fermi level tuning of Ag-doped Bi2Se3 topological insulator 5376 EN Eri Uesugi Research Institute for Interdisciplinary Science, Okayama University Takaki Uchiyama Research Institute for Interdisciplinary Science, Okayama University Hidenori Goto Research Institute for Interdisciplinary Science, Okayama University Hiromi Ota Advanced Science Research Centre, Okayama University Teppei Ueno Research Institute for Interdisciplinary Science, Okayama University Hirokazu Fujiwara Research Institute for Interdisciplinary Science, Okayama University Kensei Terashima Research Institute for Interdisciplinary Science, Okayama University Takayoshi Yokoya Research Institute for Interdisciplinary Science, Okayama University Fumihiko Matsui Graduate School of Materials Science, Nara Institute of Science and Technology Jun Akimitsu Research Institute for Interdisciplinary Science, Okayama University Kaya Kobayashi Research Institute for Interdisciplinary Science, Okayama University Yoshihiro Kubozono Research Institute for Interdisciplinary Science, Okayama University The temperature dependence of the resistivity (rho) of Ag-doped Bi2Se3 (AgxBi2-xSe3) shows insulating behavior above 35 K, but below 35 K, rho suddenly decreases with decreasing temperature, in contrast to the metallic behavior for non-doped Bi2Se3 at 1.5-300 K. This significant change in transport properties from metallic behavior clearly shows that the Ag doping of Bi2Se3 can effectively tune the Fermi level downward. The Hall effect measurement shows that carrier is still electron in AgxBi2-xSe3 and the electron density changes with temperature to reasonably explain the transport properties. Furthermore, the positive gating of AgxBi2-xSe3 provides metallic behavior that is similar to that of non-doped Bi2Se3, indicating a successful upward tuning of the Fermi level. No potential conflict of interest relevant to this article was reported.

American Chemical Society Acta Medica Okayama 15306984 19 9 2019 Asymmetric Phosphorus Incorporation in Homoepitaxial P-Doped (111) Diamond Revealed by Photoelectron Holography 5915 5919 EN T. Yokoya Research Institute for Interdisciplinary Science (RIIS), Okayama University K. Terashima Research Institute for Interdisciplinary Science (RIIS), Okayama University A. Takeda Graduate School of Science and Technology, Okayama University T. Fukura Graduate School of Science and Technology, Okayama University H. Fujiwara Graduate School of Science and Technology, Okayama University T. Muro Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8 T. Kinoshita Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8 H. Kato Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) S. Yamasaki Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) T. Oguchi Institute of Scientific and Industrial Research, Osaka University T. Wakita Research Institute for Interdisciplinary Science (RIIS), Okayama University Y. Muraoka Research Institute for Interdisciplinary Science (RIIS), Okayama University T. Matsushita Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8 Diamond has two crystallographically inequivalent sites in the unit cell. In doped diamond, dopant occupation in the two sites is expected to be equal. Nevertheless, preferential dopant occupation during growth under nonequilibrium conditions is of fundamental importance, for example, to enhance the properties of nitrogen-vacancy (N-V) centers; therefore, this is a promising candidate for a qubit. However, the lack of suitable experimental techniques has made it difficult to study the crystal- and chemical-site-resolved local structures of dopants. Here, we confirm the identity of two chemical sites with asymmetric dopant incorporation in the diamond structure, via the photoelectron holography (PEH) of heavily phosphorus (P)-doped diamond prepared by chemical vapor deposition. One is substitutionally incorporated P with preferential site occupations and the other can be attributed to a PV split vacancy complex with preferential orientation. The present study shows that PEH is a valuable technique to study the local structures around dopants with a resolution of crystallographically inequivalent but energetically equivalent sites/orientations. Such information provides strategies to improve the properties of dopant related-complexes in which alignment is crucial for sensing of magnetic field or quantum spin register using N-V centers in diamond. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 96 4 2017 Evolution of the remnant Fermi-surface state in the lightly doped correlated spin-orbit insulator Sr2-xLaxIrO4 041106 EN Kensei Terashima Research Institute for Interdisciplinary Science, Okayama University M. Sunagawa Graduate School of Natural Sciences, Okayama University H. Fujiwara Graduate School of Natural Sciences, Okayama University T. Fukura M. Fujii Graduate School of Natural Sciences, Okayama University K. Okada Aoyama Gakuin University K. Horigane Research Institute for Interdisciplinary Science, Okayama University K. Kobayashi Research Institute for Interdisciplinary Science, Okayama University R. Horie Research Institute for Interdisciplinary Science, Okayama University J. Akimitsu Research Institute for Interdisciplinary Science, Okayama University E. Golias Helmholtz-Zentrum Berlin für Materialien und Energie D. Marchenko Helmholtz-Zentrum Berlin für Materialien und Energie A. Varykhalov Helmholtz-Zentrum Berlin für Materialien und Energie N. L. Saini Dipartimento di Fisica, Universitá di Roma “La Sapienza T. Wakita Research Institute for Interdisciplinary Science, Okayama University Y. Muraoka Research Institute for Interdisciplinary Science, Okayama University T. Yokoya Research Institute for Interdisciplinary Science, Okayama University The electronic structure of the lightly electron-doped correlated spin-orbit insulator Sr2IrO4 has been studied by angle-resolved photoelectron spectroscopy. We have observed the coexistence of a lower Hubbard band and an in-gap band; the momentum dependence of the latter traces that of the band calculations without on-site Coulomb repulsion. The in-gap state remained anisotropically gapped in all observed momentum areas, forming a remnant Fermi-surface state, evolving towards the Fermi energy by carrier doping. These experimental results show a striking similarity with those observed in deeply underdoped cuprates, suggesting the common nature of the nodal liquid states observed in both compounds. No potential conflict of interest relevant to this article was reported.

The American Physical Society Acta Medica Okayama 1098-0121 90 22 2014 Proximity to Fermi-surface topological change in superconducting LaO0.54F0.46BiS2 EN Kensei Terashima Junki Sonoyama Takanori Wakita Masanori Sunagawa Kanta Ono Hiroshi Kumigashira Takayuki Muro Masanori Nagao Satoshi Watauchi Isao Tanaka Hiroyuki Okazaki Yoshihiko Takano Osuke Miura Yoshikazu Mizuguchi Hidetomo Usui Katsuhiro Suzuki Kazuhiko Kuroki Yuji Muraoka Takayoshi Yokoya The electronic structure of nearly optimally doped novel superconductor LaO1−xFxBiS2(x = 0.46) was investigated using angle-resolved photoemission spectroscopy (ARPES). We clearly observed band dispersions from 2 to 6 eV binding energy and near the Fermi level (EF), which are well reproduced by first-principles calculations when the spin-orbit coupling is taken into account. The ARPES intensity map near EF shows a squarelike distribution around the (Z) point in addition to electronlike Fermi-surface (FS) sheets around the X(R) point, indicating that FS of LaO0.54F0.46BiS2 is in close proximity to the theoretically predicted topological change. No potential conflict of interest relevant to this article was reported.