Okamoto, Jun*; Okane, Tetsuo; Saito, Yuji; Terai, Kota*; Fujimori, Shinichi; Muramatsu, Yasuji*; Yoshii, Kenji; Mamiya, Kazutoshi*; Koide, Tsuneharu*; Fujimori, Atsushi; et al.
Physical Review B, 76(18), p.184441_1 - 184441_5, 2007/11
CaSrRuO, which is ferromagnetic for Sr concentration x 0.3, has been studied by X-ray magnetic circular dichroism (XMCD) in Ru 3 and O 1 core-level X-ray absorption. XMCD signals appear at x 0.3 and monotonically increases with x in the ferromagnetic phase. While the monotonic increase of the XMCD signals with x is of a typical Stoner-type, the absence of appreciable change in the spectral line shapes of both the Ru 3 and O 1 XMCD spectra indicate that the itinerant-electron ferromagnetism in CaSrRuO is influenced by strong electron correlation.
Ishida, Yukiaki*; Hwang, J. I.*; Kobayashi, Masaki*; Takeda, Yukiharu; Mamiya, Kazutoshi*; Okamoto, Jun*; Fujimori, Shinichi; Okane, Tetsuo; Terai, Kota*; Saito, Yuji; et al.
Applied Physics Letters, 90(2), p.022510_1 - 022510_3, 2007/01
no abstracts in English
Okane, Tetsuo; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Okamoto, Jun*; Mamiya, Kazutoshi*; Muramatsu, Yasuji*; Fujimori, Atsushi; Ochiai, Akira*; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 75(Suppl.), p.105 - 106, 2006/08
no abstracts in English
Okane, Tetsuo; Takeda, Yukiharu; Fujimori, Shinichi; Terai, Kota; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika
Physica B; Condensed Matter, 378-380, p.959 - 960, 2006/05
no abstracts in English
Fujimori, Shinichi; Terai, Kota; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Yamagami, Hiroshi*; Ikeda, Shugo; Matsuda, Tatsuma; et al.
Physica B; Condensed Matter, 378-380, p.995 - 996, 2006/05
Recently, photoemission experiments in soft X-ray region have attracted much attention due to their high sensitivities for bulk electronic structures of strongly correlated electron system. We have carried out the high-resolution photoemission experiments on some uranium compounds using soft X-ray synchrotron radiation from SPring-8 to understand their electronic structures. Bulk- and U 5-sensitive band structure and Fermi surface were obtained for itinerant U 5 compounds UFeGa and USb, and they are compared with the results of the band structure calculations treating U 5 states as being itinerant. In addition, we show the results of photoemission study on some heavy fermion compounds such as UPdAl and UNiAl. The temperature dependences of the U 5 electronic structure of UPdAl will be also reported.
Fujimori, Shinichi; Terai, Kota; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Yamagami, Hiroshi*; Tokiwa, Yoshifumi*; Ikeda, Shugo; et al.
Physical Review B, 73(12), p.125109_1 - 125109_6, 2006/03
We have performed angle-resolved photoemission spectroscopy (ARPES) experiments on paramagnetic UFeGa using soft X-ray synchrotron radiation (=500 eV) and derived the bulk- and U 5-sensitive electronic structure of UFeGa. Although the agreement between the experimental band strucure and the LDA calculation treating U 5 electrons as beeing itinerant is qualitative, the morphology of the Fermi surface is well explained by the calculation. This result claims that the importance of the electron correlation effect even for the itinerant U 5 compound.
Okane, Tetsuo; Okamoto, Jun*; Mamiya, Kazutoshi*; Fujimori, Shinichi; Takeda, Yukiharu; Saito, Yuji; Muramatsu, Yasuji*; Fujimori, Atsushi*; Haga, Yoshinori; Yamamoto, Etsuji; et al.
Journal of the Physical Society of Japan, 75(2), p.024704_1 - 024704_5, 2006/02
no abstracts in English
Imazono, Takashi; Hirono, Toko*; Kimura, Hiroaki*; Saito, Yuji; Ishino, Masahiko; Muramatsu, Yasuji*; Koike, Masato; Sano, Kazuo*
Review of Scientific Instruments, 76(12), p.126106_1 - 126106_4, 2005/12
Polarizance of a reflection-type polarizer made with a synthetic mica (fluorophlogopite) single crystal was evaluated at the photon energy of 880 eV by means of the rotating-analyzer method in conjunction with the evaluation of the degree of linear polarization of the insertion beamline, SPring-8 BL23SU, featuring an APPLE-2 type variably polarizing undulator. When the undulator was tuned to the horizontal linear polarization mode, the maximum reflectances for s- and p-polarization for a symmetric Bragg reflection of synthetic mica(002) were 2.6% and 0.013%, respectively, at incident angles of near 45. Our analysis based on the rotating-analyzer method gave the polarizance of the polarizer of at least 0.997 0.002 and the degree of linear polarization of 0.993 0.004 in the linear polarization mode.
Kobayashi, Masaki*; Ishida, Yukiaki*; Hwang, J. I.*; Mizokawa, Takashi*; Fujimori, Atsushi*; Mamiya, Kazutoshi*; Okamoto, Jun*; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; et al.
Physical Review B, 72(20), p.201201_1 - 201201_4, 2005/11
no abstracts in English
Muramatsu, Yasuji; Yamashita, Michiru*; Motoyama, Muneyuki*; Hirose, Mika*; Denlinger, J. D.*; Gullikson, E. M.*; Perera, R. C. C.*
X-Ray Spectrometry, 34(6), p.509 - 513, 2005/11
Surface carbon films on the weathered Japanese roof tiles were characterized by soft X-ray spectroscopy. From the X-ray absorption measurements, it was confirmed that the surface carbon films were oxidized by weathering. On the ohterhand, from the X-ray emission measurements, it can be confirmed that the degree of the orientation was kept in the inner carbon films.
Iihara, Junji*; Muramatsu, Yasuji; Takebe, Toshihiko*; Sawamura, Akitaka*; Namba, Akihiko*; Imai, Takahiro*; Denlinger, J. D.*; Perera, R. C. C.*
Japanese Journal of Applied Physics, Part 1, 44(9A), p.6612 - 6617, 2005/09
Electronic structure transition between semiconducting and metallic states in boron (B) -doped diamonds was element-selectively observed by soft X-ray emission and absorption spectroscopy using synchrotron radiation. For the lightly B-doped diamonds, the B 2-density of states (DOS) in the valence band were enhanced with a steep-edge-feature near the Fermi level, and localized acceptor levels, characteristic of semiconductors, were clearly observed both in B 2- and C 2-DOS in the conduction bands. For the heavily B-doped diamonds, the localized acceptor levels developed into extended energy levels and new energy levels were generated to form an extended conduction band structure which overlapped with the valence band. Thus, this clarified that the metallic energy band structure is actually formed by heavy boron doping. Such valence and conduction band structures observed by soft X-ray emission and absorption spectroscopy well accounted for the electrical properties of the B-doped diamonds.
Rigaku Janaru, 36(1), p.35 - 42, 2005/04
Microstructure and weathering effects of carbon films on the Japanese smoked roof tile "Ibushi-Kawara" were investigated by soft X-ray spectroscopy using synchrotron radiation. The take-off/incident-angle dependence on the X-ray emission/absorption spectra of Kawara shows that the carbon-black-like sp2 carbon atoms partially form a layer structure oriented parallel to the basal clay plane, and that the degree of orientation of the carbon films is estimated to be 50% that of highly oriented pyrolytic graphite (HOPG). X-ray absorption measurements revealed that weathering oxidizes the carbon films and partial carboxy chemical bonding occurs.
Okamoto, Jun*; Mamiya, Kazutoshi*; Fujimori, Shinichi; Okane, Tetsuo; Saito, Yuji; Muramatsu, Yasuji*; Yoshii, Kenji; Fujimori, Atsushi*; Tanaka, Arata*; Abbate, M.*; et al.
Physical Review B, 71(10), p.104401_1 - 104401_5, 2005/03
The antiferromagnetic-to-ferromagnetic transition in SrFeCoO (0.15) induced by Co doping has been studied by magnetic circular X-ray dichroism. The orbital and spin magnetic moments of the Fe and Co 3 states under the magenetic field of 2 T are found to show different dependences: The spin polarization of Fe 3 gradually increases with Co concentration; On the other hand, a large spin polarization of Co 3 is induced already in the antiferromagnetic phase, indicating that the Co moment is nearly fully alligned already in the antiferromagnetic phase. This suggests that the alignment of the Fe magnetic moment in SrFeCoO is induced by interaction with doped Co magnetic moment. Possible formation of ferromagnetic Co rich region is discussed.
X-sen Bunseki No Shimpo, 36, p.47 - 62, 2005/03
Research trends in soft X-ray absorption, electron, and soft X-ray emission spectroscopies using synchrotron radiation for chemical analysis are briefly explained. Measurements in the higher-energy region over 2 keV, liquid sample measurements, and MCD measurements have recently been achieved in the soft X-ray absorption spectroscopy. In electron spectroscopy, high-resolution measurements and bulk-sensitive measurements using higher-energy excitation have been achieved. In soft X-ray emission spectroscopy, higher-resolution X-ray spectrometers have been developed and liquid-sample measurements have also been achieved. In addition, chemical analysis of surface carbon films on Japanese smoked roof tiles and electronic structure analysis of boron-doped diamond are demonstrated as the successful analytical studies using soft X-ray spectroscopy.
Muramatsu, Yasuji; Yamashita, Michiru*; Motoyama, Muneyuki*; Denlinger, J. D.*; Gullikson, E. M.*; Perera, R. C. C.*
Spectrochimica Acta, Part B, 59(8), p.1317 - 1322, 2004/08
Polarized emission spectra from graphite have been measured by an EPMA and discussed by means of molecular orbital calculation of 2p electrons densities of state of graphite by some of the present authors. The present study treats the refined measurements of the polarized C K-emission band spectra from the highly oriented pyrolytic graphite (HOPG) and discusses the structure of the surface carbons of Japanese traditional smoked roof tiles, Ibushi Kawara.
Muramatsu, Yasuji; Tomizawa, Kana; Denlinger, J. D.*; Perera, R. C. C.*
Journal of Electron Spectroscopy and Related Phenomena, 137-140(1-3), p.823 - 826, 2004/07
High-resolution CK X-ray emission spectra of polycyclic aromatic hydrocarbons (PAH) were measured using synchrotron radiation. The main peak energies in the PAH X-ray spectra shifted to a higher energy region as the ratio of hydrogenated outer carbon atoms to the non-hydrogenated inner carbon atoms increased. Discrete variational (DV)-X molecular orbital calculations provided theoretical confirmation that the spectral features depend on the ratio of hydrogenated/non-hydrogenated carbon atoms, which suggests that the features around the main peaks provide the information of the degree of hydrogenation in PAH compounds.
Yamamoto, Tomoyuki*; Mizoguchi, Teruyasu*; Tatsumi, Kazuyoshi*; Tanaka, Isao*; Adachi, Hirohiko*; Muramatsu, Yasuji; Gullikson, E. M.*; Perera, R. C. C.*
Materials Transactions, 45(7), p.1991 - 1993, 2004/07
First principles calculations have been carried out to investigate the core-hole effects on the theoretical fine structures of the X-ray absorption spectra of MgF and ZnF ath FK-edge. Experimental profiles of the near-edge X-ray absorption fine structures are well reproduced by the theoretical calculations when the core-hole effect is introduced. The dependence of supercell size on the theoretical fine structures is also examined.
Okane, Tetsuo; Fujimori, Shinichi; Mamiya, Kazutoshi; Okamoto, Jun; Muramatsu, Yasuji; Fujimori, Atsushi; Suzuki, Hiroyuki*; Matsumoto, Takehiko*; Furubayashi, Takao*; Isobe, Masaaki*; et al.
Journal of Magnetism and Magnetic Materials, 272-276(Suppl.), p.e297 - e298, 2004/05
The electronic structure of spinel-type chalcogenide CuIrS, which exhibits a metal-insulator transition (MIT) as a function of temperature, has been studied by photoemission spectroscopy (PES). Below the transition temperature , the valence-band PES spectra indicate a gap formation, while the overall valence-band structure is shifted to the higher binding-energy side. The line shape of the Ir 4 core-level PES spectra shows a dramatic change across , which may be associated with the variation of the Ir 5 electron states.
Okane, Tetsuo; Okamoto, Jun; Mamiya, Kazutoshi; Fujimori, Shinichi; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Ochiai, Akira*
Physica B; Condensed Matter, 345(1-4), p.221 - 224, 2004/03
Magnetic circular dichroism (MCD) has been measured at the U absorption edges of ferromagnetic uranium monochalcogenides US, USe and UTe. The MCD signals are weaker in US than in USe and UTe. Both the spin and orbital moments are increased in going from US to USe, and then reduced from USe to UTe.
Muramatsu, Yasuji; Gullikson, E. M.*; Perera, R. C. C.*
X-sen Bunseki No Shimpo, 35, p.125 - 136, 2004/00
Soft X-ray emission and absorption spectra in the CK region of typical solid carbon compounds (HOPG, carbon nanotube, diamond, fullerene, polyethylene, -terphenyl, anthracene) are demonstrated. Take-off/incident-angle dependent X-ray spectra of HOPG are also shown to utilize for the structural analysis of anistropic crystals. Spectral analysis of these compounds using discrete variational (DV)-X molecular orbital calclations is also demonstrated.