Effect of Mn substitution on the electronic structure for Mn-doped indium-tin oxide films studied by soft and hard X-ray photoemission spectroscopy

Otsuki, Daiki*; Ishida, Tatsuhiro*; Tsutsumi, Naoya*; Kobayashi, Masaki*; Inagaki, Kodai*; Yoshida, Teppei*; Takeda, Yukiharu; Fujimori, Shinichi; Yasui, Akira*; Kitagawa, Saiki*; et al.

Physical Review Materials (Internet), 7(12), p.124601_1 - 124601_6, 2023/12

https://doi.org/10.1103/PhysRevMaterials.7.124601

Investigation of the electronic structure of the MgZnY alloy using X-ray photoelectron spectroscopy

Miyazaki, Hidetoshi*; Akatsuka, Tatsuyoshi*; Kimura, Koji*; Egusa, Daisuke*; Sato, Yohei*; Itakura, Mitsuhiro; Takagi, Yasumasa*; Yasui, Akira*; Ozawa, Kenichi*; Mase, Kazuhiko*; et al.

Materials Transactions, 64(6), p.1194 - 1198, 2023/06

https://doi.org/10.2320/matertrans.MT-MD2022019

We investigated the electronic structure of the MgZnY alloy using hard and soft X-ray photoemission spectroscopy and electronic band structure calculations to understand the mechanism of the phase stability of this material. Electronic structure of the MgZnY alloy showed a semi-metallic electronic structure with a pseudo-gap at the Fermi level. The observed electronic structure of the MgZnY alloy suggests that the presence of a pseudogap structure is responsible for phase stability.

Revising the 4 symmetry in CeCuGe; Soft X-ray absorption and hard X-ray photoemission spectroscopy

Aratani, Hidekazu*; Nakatani, Yasuhiro*; Fujiwara, Hidenori*; Kawada, Moeki*; Kanai, Yuina*; Yamagami, Kohei*; Fujioka, Shuhei*; Hamamoto, Satoru*; Kuga, Kentaro*; Kiss, Takayuki*; et al.

Physical Review B, 98(12), p.121113_1 - 121113_6, 2018/09

AA2018-0352.pdf:1.16MB

https://doi.org/10.1103/PhysRevB.98.121113

Nanoscale spatial analysis of clay minerals containing cesium by synchrotron radiation photoemission electron microscopy

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

https://doi.org/10.1063/1.5005799

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.

Exotic hadrons from heavy ion collisions

Cho, S.*; Hyodo, Tetsuo*; Jido, Daisuke*; Ko, C. M.*; Lee, S. H.*; Maeda, Saori*; Miyahara, Kenta*; Morita, Kenji*; Nielsen, M.*; Onishi, Akira*; et al.

Progress in Particle and Nuclear Physics, 95, p.279 - 322, 2017/07

AA2016-0538.pdf:0.74MB

https://doi.org/10.1016/j.ppnp.2017.02.002

With upgraded detectors at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), it has become possible to measure hadrons beyond their ground states in high energy heavy ion collisions. Therefore, heavy ion collisions provide a new method for studying exotic hadrons that are either molecular states made of various hadrons or compact system consisting of muliquarks. Because their structures are related to the fundamental properties of Quantum Chromodynamics (QCD), studying exotic hadrons is currently one of the most active areas of research in hadron physics. The present review is a summary of the current understanding of a selected set of exotic candidate particles that can be potentially measured in heavy ion collisions.

Electronic structures of ferromagnetic CeAgSb; Soft X-ray absorption, magnetic circular dichroism, and angle-resolved photoemission spectroscopies

Saito, Yuji; Fujiwara, Hidenori*; Yamaguchi, Takashi*; Nakatani, Yasuhiro*; Mori, Takeo*; Fuchimoto, Hiroto*; Kiss, Takayuki*; Yasui, Akira*; Miyawaki, Jun*; Imada, Shin*; et al.

Journal of the Physical Society of Japan, 85(11), p.114713_1 - 114713_7, 2016/11

https://doi.org/10.7566/JPSJ.85.114713

We report on the electronic structures of ferromagnetic CeAgSb using soft X-ray absorption (XAS), magnetic circular dichroism (XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce XAS spectra show very small satellite structures, reflecting a strongly localized character of the Ce 4 electrons. The linear dichroism effects in the Ce XAS spectra demonstrate the ground-state Ce 4 symmetry of , the spatial distribution of which is directed along the -axis. Nevertheless, ARPES spectra at the Ce 3-4 resonance show the momentum dependence of the intensity ratio between Ce 4 and 4 peaks in a part of the Brillouin zone, suggesting the non negligible momentum-dependent hybridization effect between the Ce 4 and the conduction electrons. This is associated with the moderate mass enhancement in CeAgSb.

Probing strongly correlated 4-orbital symmetry of the ground state in Yb compounds by linear dichroism in core-level photoemission

Mori, Takeo*; Kitayama, Satoshi*; Kanai, Yuina*; Naimen, Sho*; Fujiwara, Hidenori*; Higashiya, Atsushi*; Tamasaku, Kenji*; Tanaka, Arata*; Terashima, Kensei*; Imada, Shin*; et al.

Journal of the Physical Society of Japan, 83(12), p.123702_1 - 123702_5, 2014/12

https://doi.org/10.7566/JPSJ.83.123702

We show that the strongly correlated 4-orbital symmetry of the ground state is revealed by linear dichroism in core-level photoemission spectra, as we have discovered for YbRhSi and YbCuSi. Theoretical analysis shows us that the linear dichroism reflects the anisotropic charge distributions resulting from a crystalline electric field. We have successfully determined the ground-state 4 symmetry for both compounds from the polarization-dependent angle resolved core-level spectra at a temperature well below the first excitation energy. The excited-state symmetry is also probed by temperature dependence of the linear dichroism where the high measurement temperatures are on the order of the crystal-field-splitting energies.

Itinerant magnetism in URhGe revealed by angle-resolved photoelectron spectroscopy

Fujimori, Shinichi; Kawasaki, Ikuto*; Yasui, Akira*; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi*; Yamagami, Hiroshi; Haga, Yoshinori; Yamamoto, Etsuji; et al.

Physical Review B, 89(10), p.104518_1 - 104518_7, 2014/03

https://doi.org/10.1103/PhysRevB.89.104518

The electronic structure of the ferromagnetic superconductor URhGe in the paramagnetic phase has been studied by angle-resolved photoelectron spectroscopy using soft X rays ( = 595-700 eV). Dispersive bands with large contributions from U 5 states were observed in the ARPES spectra, and form Fermi surfaces. The band structure in the paramagnetic phase is partly explained by the band-structure calculation treating all U 5 electrons as being itinerant, suggesting that an itinerant description of U 5 states is a good starting point for this compound. On the other hand, there are qualitative disagreements especially in the band structure near the Fermi level ( 0.5 eV). The experimentally observed bands are less dispersive than the calculation, and the shape of the Fermi surface is different from the calculation. The changes in spectral functions due to the ferromagnetic transition were observed in bands near the Fermi level, suggesting that the ferromagnetism in this compound has an itinerant origin.

Observation of bulk band dispersions of YbRhSi using soft X-ray angle-resolved photoemission spectroscopy

Yasui, Akira*; Saito, Yuji; Fujimori, Shinichi; Kawasaki, Ikuto*; Okane, Tetsuo; Takeda, Yukiharu; Lapertot, G.*; Knebel, G.*; Matsuda, Tatsuma*; Haga, Yoshinori; et al.

Physical Review B, 87(7), p.075131_1 - 075131_6, 2013/02

https://doi.org/10.1103/PhysRevB.87.075131

We have performed soft X-ray angle-resolved photoemission spectroscopy (ARPES) measurements on YbRhSi and clarified its three-dimensional bulk valence-band structures. The ARPES spectra have not only Yb multiplet peaks but also a finite contribution of Yb peaks at 15 K, corresponding to the valence fluctuating behavior in this compound. This means that Yb 4f electrons in this compound have itinerant character below the . We have found that dispersions of the valence bands except the vicinity of the Yb 4f bands agree better with those of the band-structure calculation of LuRhSi than those of YbRhSi within a local-density approximation. In addition, the Yb 3d-4f resonant photoemission spectra of YbRhSi strongly suggest the existence of Yb 5d electrons in the valence band. We conclude that the charge transfer from the Yb 4f state to the Yb 5d state has an important role in the formation of the valence band of YbRhSi.

Itinerant U 5 nature in antiferromagnet U(RuRh)Si; Soft X-ray angle-resolved photoemission spectroscopy

Kawasaki, Ikuto; Fujimori, Shinichi; Okane, Tetsuo; Yasui, Akira; Saito, Yuji; Yamagami, Hiroshi*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*

Journal of the Physical Society of Japan, 80(12), p.124710_1 - 124710_5, 2011/12

https://doi.org/10.1143/JPSJ.80.124710

We have carried out soft X-ray angle-resolved photoemission spectroscopy experiments on U(RuRh)Si, which shows antiferromagnetic (AFM) ordering at low temperatures. We have revealed that U 5 electrons contribute to the formation of the energy band as well as Fermi surface. This suggests that the AFM ordering is caused by a spin density wave of itinerant U 5 electrons. The observed band dispersion and Fermi surface are nearly identical to those of URuSi. Therefore, the AFM ordering vector = (1,0,0) can be a possible ordering vector of the hidden order phase in URuSi.