Electronic structures of ferromagnetic superconductors UGe and UCoGe studied by angle-resolved photoelectron spectroscopy

Fujimori, 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

https://doi.org/10.1103/PhysRevB.91.174503

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.

The SNARE protein SYP71 expressed in vascular tissues is involved in symbiotic nitrogen fixation in nodules

Hakoyama, Tsuneo*; Oi, Ryo*; Hazuma, Kazuya*; Suga, Eri*; Adachi, Yuka*; Kobayashi, Mayumi*; Akai, Rie*; Sato, Shusei*; Fukai, Eigo*; Tabata, Satoshi*; et al.

Plant Physiology, 160(2), p.897 - 905, 2012/10

https://doi.org/10.1104/pp.112.200782

Electronic structure of heavy fermion uranium compounds studied by core-level photoelectron spectroscopy

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

https://doi.org/10.1143/JPSJ.81.014703

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.

Band structures of CeRu(SiGe) studied by resonant soft X-ray ARPES

Okane, 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

Electronic states of magnetic refrigerator materials MnFePAs using soft X-ray magnetic circular dichroism

Takeda, 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

https://doi.org/10.1088/1742-6596/200/1/012199

no abstracts in English

Bulk 5 electronic states of the uranium monochalcogenide US as seen via soft X-ray photoemission

Takeda, 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

https://doi.org/10.1103/PhysRevB.80.161101

no abstracts in English

Observation of itinerant Ce 4 electronic states in CeIrSi studied by angle-resolved Ce 3 resonance photoemission spectroscopy

Okochi, 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

https://doi.org/10.1143/JPSJ.78.084802

We have applied angle-resolved Ce 34 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.

Experimental observation of bulk band dispersions in the oxide semiconductor ZnO using soft X-ray angle-resolved photoemission spectroscopy

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

BB2009-1947.pdf:0.84MB

https://doi.org/10.1063/1.3116223

4-derived Fermi surfaces of CeRu(SiGe) near the quantum critical point; Resonant soft-X-ray ARPES study

Okane, Tetsuo; Okochi, Takuo*; Takeda, Yukiharu; Fujimori, Shinichi; Yasui, Akira; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi; Matsumoto, Yuji*; Sugi, Motoki*; et al.

Physical Review Letters, 102(21), p.216401_1 - 216401_4, 2009/05

https://doi.org/10.1103/PhysRevLett.102.216401

Observation of 5 electrons in the itinerant limit; Three-dimensional electronic structure of UB

Okochi, Takuo; Fujimori, Shinichi; Yamagami, Hiroshi*; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*

Physical Review B, 78(16), p.165110_1 - 165110_5, 2008/10

https://doi.org/10.1103/PhysRevB.78.165110

We have derived the three dimensional band structure and Fermi surfaces of itinerant uranium compound UB by soft X-ray angle resolved photoelectron spectroscopy. We have observed clear energy dispersions and Fermi surfaces with large contribution from U 5 states. The obtained results have been compared with the result of band-structure calculation within the local density functional approximation as well as the results of dHvA study. The qualitative agreement has been obtained in the size and topology of the Fermi surfaces with the band structure calculation and the dHvA measurement. Meanwhile, their band structure near the Fermi level is slightly different from the calculation. This might be due to a dynamic renormalization beyond the LDA band calculations even in the very itinerant 5 compound.