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Yoshigoe, Akitaka; Shiwaku, Hideaki; Kobayashi, Toru; Shimoyama, Iwao; Matsumura, Daiju; Tsuji, Takuya; Nishihata, Yasuo; Kogure, Toshihiro*; Okochi, Takuo*; Yasui, Akira*; et al.
Applied Physics Letters, 112(2), p.021603_1 - 021603_5, 2018/01
Times Cited Count：6 Percentile：27.84(Physics, Applied)A synchrotron radiation photoemission electron microscope (SR-PEEM) was applied to demonstrate pinpoint analysis of micrometer-sized weathered biotite clay particles with artificially adsorbed cesium (Cs) atoms. Despite the insulating properties of the clay, we observed the spatial distributions of constituent elements (Si, Al, Cs, Mg, Fe) without charging issues. We found that Cs atoms were likely to be adsorbed evenly over the entire particle. Spatially-resolved X-ray absorption spectra (XAS) of the Cs M
-edge region showed Cs to be present in a monocation state (Cs
). Further pinpoint XAS measurements were also performed at the Fe L
-edge to determine the chemical valence of the Fe atoms. Our results demonstrate the utility of SR-PEEM as a tool for spatially-resolved chemical analyses of various environmental substances, which is not limited by the poor conductivity of samples.
and UCoGe studied by angle-resolved photoelectron spectroscopyFujimori, Shinichi; Okochi, Takuo*; Kawasaki, Ikuto*; Yasui, Akira*; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; et al.
Physical Review B, 91(17), p.174503_1 - 174503_9, 2015/05
Times Cited Count：27 Percentile：69.20(Materials Science, Multidisciplinary)The electronic structures of the ferromagnetic superconductors UGe
and UCoGe in the paramagnetic phase were studied by angle-resolved photoelectron spectroscopy using soft X-rays (
= 400-500 eV). The quasi-particle bands with large contributions from U 5
states were observed in the vicinity of EF, suggesting that the U 5 electrons of these compounds have an itinerant character. Their overall band structures were explained by the band-structure calculations treating all the U 5 electrons as being itinerant. Meanwhile, the states in the vicinity of EF show considerable deviations from the results of band-structure calculations, suggesting that the shapes of Fermi surface of these compounds are qualitatively different from the calculations, possibly caused by electron correlation effect in the complicated band structures of the low-symmetry crystals. Strong hybridization between U 5 and 
states in UCoGe were found by the 
2p-3d resonant photoemission experiment, suggesting that states have finite contributions to the magnetic, transport, and superconducting properties.
Koide, Tetsuya*; Sato, Takahiro; Koka, Masashi; Saito, Yuichi; Kamiya, Tomihiro; Okochi, Takuo*; Kotsugi, Masato*; Kinoshita, Toyohiko*; Nakamura, Tetsuya*; Iwase, Akihiro*; et al.
Japanese Journal of Applied Physics, 53(5S1), p.05FC06_1 - 05FC06_4, 2014/05
Times Cited Count：12 Percentile：45.92(Physics, Applied)We previously reported that the magnetic state of FeRh can be controlled by irradiation with ion beams. In this paper, we evaluate possibility of magnetic patterning on FeRh thin films using energetic light ion microbeam irradiation with various shapes and dimensions. Proton microbeam irradiation with 2 MeV was performed at JAEA-Takasaki to produce micron-sized magnetic patterns. XMCD-PEEM observation was performed at SPring8 to confirm the synthesized magnetic patterns. As a result, the XMCD-PEEM images of the various micrometer sized patters in FeRh film were observed using 2 MeV H ion beam. The observed bright regions are considered to have ferromagnetic spin orders, in contrast that the gray areas have anti-ferromagnetic spin order. Since the brightness of the PEEM images is strongly correlated with the magnetization of the samples, we reveal that the magnetic state in local regions of the FeRh thin films can be controlled by changing the ion fluences.
states in uranium mononitride revealed by angle-resolved photoelectron spectroscopyFujimori, Shinichi; Okochi, Takuo*; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika
Physical Review B, 86(23), p.235108_1 - 235108_8, 2012/12
Times Cited Count：36 Percentile：77.87(Materials Science, Multidisciplinary)The electronic structure of the antiferromagnet uranium nitride (UN) has been studied by angle resolved photoelectron spectroscopy using soft X-rays. The band structure as well as the Fermi surfaces in the paramagnetic phase are well explained by the band-structure calculation treating all the U 5 electrons as being itinerant, suggesting that itinerant description of the U 5 states is appropriate for this compound. On the other hand, changes in the spectral function due to the antiferromagnetic transition were very small. The shapes of the Fermi surfaces in a paramagnetic phase are highly three-dimensional, and the nesting of Fermi surfaces is unlikely as the origin of the magnetic ordering.
Ide, Takayuki*; Kawai, Yusuke*; Handa, Hiroyuki*; Fukidome, Hirokazu*; Kotsugi, Masato*; Okochi, Takuo*; Enta, Yoshiharu*; Kinoshita, Toyohiko*; Yoshigoe, Akitaka; Teraoka, Yuden; et al.
Japanese Journal of Applied Physics, 51(6), p.06FD02_1 - 06FD02_4, 2012/06
Times Cited Count：7 Percentile：29.76(Physics, Applied)
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molecular ferromagnetic 
-Mn phthalocyanine studied by soft X-ray magnetic circular dichroismKataoka, Takashi*; Sakamoto, Yuta*; Yamazaki, Yo*; Singh, V. R.*; Fujimori, Atsushi*; Takeda, Yukiharu; Okochi, Takuo*; Fujimori, Shinichi; Okane, Tetsuo; Saito, Yuji; et al.
Solid State Communications, 152(9), p.806 - 809, 2012/05
Times Cited Count：21 Percentile：62.29(Physics, Condensed Matter)no abstracts in English
Aiko, Kazuma*; Toki, Atsushi*; Matsui, Toshiyuki*; Iwase, Akihiro*; Sato, Takahiro; Takano, Katsuyoshi*; Koka, Masashi; Saito, Yuichi; Kamiya, Tomihiro; Okochi, Takuo*; et al.
Journal of Synchrotron Radiation, 19(2), p.223 - 226, 2012/03
Times Cited Count：7 Percentile：35.97(Instruments & Instrumentation)Fujimori, Shinichi; Okochi, Takuo*; Kawasaki, Ikuto; Yasui, Akira; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 81(1), p.014703_1 - 014703_9, 2012/01
Times Cited Count：38 Percentile：82.02(Physics, Multidisciplinary)High-energy-resolution core-level and valence-band photoelectron spectroscopic studies were performed for the heavy Fermion uranium compounds UGe, UCoGe, URhGe, URuSi, UNiAl
, UPdAl, and UPt as well as typical localized and itinerant uranium compounds to understand the relationship between the uranium valence state and their core-level spectral line shapes. The core-level spectra of UGe, UCoGe, URhGe, URuSi, and UNiAl are rather similar to those of itinerant compounds, suggesting that U 5 electrons in these compounds are well hybridized with ligand states. On the other hand, the core-level spectra of UPdAl and UPt show considerably different spectral line shapes from those of the itinerant compounds, suggesting that U 5 electrons in UPdAl and UPt are less hybridized with ligand states, leading to the correlated nature of U 5 electrons in these compounds.
Fukidome, Hirokazu*; Abe, Shunsuke*; Takahashi, Ryota*; Imaizumi, Kei*; Inomata, Shuya*; Handa, Hiroyuki*; Saito, Eiji*; Enta, Yoshiharu*; Yoshigoe, Akitaka; Teraoka, Yuden; et al.
Applied Physics Express, 4(11), p.115104_1 - 115104_3, 2011/11
Times Cited Count：35 Percentile：77.75(Physics, Applied)Fukidome, Hirokazu*; Takahashi, Ryota*; Abe, Shunsuke*; Imaizumi, Kei*; Handa, Hiroyuki*; Kang, H. C.*; Karasawa, Hiromi*; Suemitsu, Tetsuya*; Otsuji, Taiichi*; Enta, Yoshiharu*; et al.
Journal of Materials Chemistry, 21(43), p.17242 - 17248, 2011/11
Times Cited Count：28 Percentile：62.37(Chemistry, Physical)
studied by photoemission and soft X-ray absorption spectroscopiesUtsumi, Yuki*; Sato, Hitoshi*; Kurihara, Hidenao*; Maso, Hiroyuki*; Hiraoka, Koichi*; Kojima, Kenichi*; Tobimatsu, Komei*; Okochi, Takuo*; Fujimori, Shinichi; Takeda, Yukiharu; et al.
Physical Review B, 84(11), p.115143_1 - 115143_7, 2011/09
Times Cited Count：12 Percentile：45.97(Materials Science, Multidisciplinary)We have studied conduction-band (CB) electronic states of a typical valence-transition compound YbInCu by means of temperature-dependent hard X-ray photoemission spectroscopy (HX-PES), soft X-ray absorption spectroscopy (XAS), and soft X-ray photoemission spectroscopy (SX-PES) of the valence band. We have described the valence transition in YbInCu in terms of the charge transfer from the CB to Yb 4 states.
SiOkane, Tetsuo; Kawasaki, Ikuto; Yasui, Akira; Okochi, Takuo*; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi; Matsumoto, Yuji*; et al.
Journal of the Physical Society of Japan, 80(Suppl.A), p.SA060_1 - SA060_3, 2011/07
Times Cited Count：1 Percentile：11.10(Physics, Multidisciplinary)(Si
Ge
) studied by resonant soft X-ray ARPESOkane, Tetsuo; Okochi, Takuo*; Takeda, Yukiharu; Fujimori, Shinichi; Yasui, Akira; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi; Matsumoto, Yuji*; Sugi, Motoki*; et al.
Physica Status Solidi (B), 247(3), p.397 - 399, 2010/03
Kataoka, Takashi*; Kobayashi, Masaki*; Sakamoto, Yuta*; Song, G. S.*; Fujimori, Atsushi*; Chang, F.-H.*; Lin, H.-J.*; Huang, D. J.*; Chen, C. T.*; Okochi, Takuo*; et al.
Journal of Applied Physics, 107(3), p.033718_1 - 033718_7, 2010/02
Times Cited Count：55 Percentile：85.97(Physics, Applied)
Fe
P
As
using soft X-ray magnetic circular dichroismTakeda, Yukiharu; Okane, Tetsuo; Okochi, Takuo*; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Yabuta, Hisato*; Takabatake, Toshiro*
Journal of Physics; Conference Series, 200, p.012199_1 - 012199_4, 2010/02
Times Cited Count：2 Percentile：63.83(Materials Science, Multidisciplinary)no abstracts in English
electronic states of the uranium monochalcogenide US as seen via soft X-ray photoemissionTakeda, Yukiharu; Okane, Tetsuo; Okochi, Takuo*; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi*; Ochiai, Akira*
Physical Review B, 80(16), p.161101_1 - 161101_4, 2009/10
Times Cited Count：8 Percentile：35.82(Materials Science, Multidisciplinary)no abstracts in English
; X-ray magnetic circular dichroism studyOkane, Tetsuo; Okochi, Takuo*; Inami, Toshiya; Takeda, Yukiharu; Fujimori, Shinichi; Kawamura, Naomi*; Suzuki, Motohiro*; Tsutsui, Satoshi*; Yamagami, Hiroshi; Fujimori, Atsushi; et al.
Physical Review B, 80(10), p.104419_1 - 104419_7, 2009/09
Times Cited Count：6 Percentile：28.67(Materials Science, Multidisciplinary) electronic states in CeIrSi studied by angle-resolved Ce 3
resonance photoemission spectroscopyOkochi, Takuo*; Toshimitsu, Takafumi*; Yamagami, Hiroshi; Fujimori, Shinichi; Yasui, Akira; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Miyauchi, Yuichiro*; et al.
Journal of the Physical Society of Japan, 78(8), p.084802_1 - 084802_6, 2009/08
Times Cited Count：10 Percentile：53.99(Physics, Multidisciplinary)We have applied angle-resolved Ce 3
4 resonance photoemission spectroscopy to the non-centrosymmetric pressure-induced superconductor CeIrSi and obtained the 4 band-structure and Fermi surfaces. We have found that the Ce 4 states are located mainly near the Fermi level and that the photoemission intensity derived from the dispersive conduction bands across the Fermi level shows considerable resonant enhancement. In addition, the band structure and Fermi surfaces of CeIrSi are different from those of the non- reference compound, LaIrSi and the difference is well explained by the band structure calculated within the local density approximation (LDA). These results strongly suggest that the Ce 4 electrons in CeIrSi are well hybridized with conduction bands and form itinerant electronic states.
MnAs studied by X-ray magnetic circular dichroismTakeda, Yukiharu; Kobayashi, Masaki*; Okane, Tetsuo; Okochi, Takuo*; Okamoto, Jun*; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Fujimori, Atsushi*; Tanaka, Arata*; et al.
Hoshako, 22(4), p.202 - 209, 2009/07
no abstracts in English
Kobayashi, Masaki*; Song, G.-S.*; Kataoka, Takashi*; Sakamoto, Yuta*; Fujimori, Atsushi; Okochi, Takuo*; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Yamagami, Hiroshi; et al.
Journal of Applied Physics, 105(12), p.122403_1 - 122403_4, 2009/06
Times Cited Count：13 Percentile：46.82(Physics, Applied)
