Nature of structural instabilities in superconducting SrIrSn

Kaneko, Koji; Cheung, Y. W.*; Hu, Y.*; Imai, Masaki*; Tanioku, Yasuaki*; Kanagawa, Hibiki*; Murakawa, Joichi*; Moriyama, Kodai*; Zhang, W.*; Lai, K. T.*; et al.

JPS Conference Proceedings (Internet), 30, p.011032_1 - 011032_6, 2020/03

https://doi.org/10.7566/JPSCP.30.011032

Zeolitic vanadomolybdates as high-performance cathode-active materials for sodium-ion batteries

Zhang, Z,*; Wang, H.*; Yoshikawa, Hirofumi*; Matsumura, Daiju; Hatao, Shuya*; Ishikawa, Satoshi*; Ueda, Wataru*

ACS Applied Materials & Interfaces, 12(5), p.6056 - 6063, 2020/02

https://doi.org/10.1021/acsami.9b19808

Lattice dynamics in FeSe via inelastic X-ray scattering and first-principles calculations

Murai, Naoki; Fukuda, Tatsuo; Nakajima, Masamichi*; Kawamura, Mitsuaki*; Ishikawa, Daisuke*; Tajima, Setsuko*; Baron, A. Q. R.*

Physical Review B, 101(3), p.035126_1 - 035126_6, 2020/01

https://doi.org/10.1103/PhysRevB.101.035126

We report an inelastic X-ray scattering investigation of phonons in FeSe superconductor. Comparing the experimental phonon dispersion with density functional theory (DFT) calculations in the non-magnetic state, we found a significant disagreement between them. A better overall agreement was obtained by allowing for spin-polarization in DFT calculations, despite the absence of magnetic order in FeSe. This calculation gives a realistic approximation, at DFT level, of the disordered paramagnetic state of FeSe, in which strong spin fluctuations are present.

X-ray absorption spectroscopy and magnetocaloric study of PrSrCoO (00.5)

Matsumura, Daiju; Tsuji, Takuya; Yoshii, Kenji

Materials Chemistry and Physics, 238, p.121885_1 - 121885_5, 2019/12

https://doi.org/10.1016/j.matchemphys.2019.121885

We have conducted X-ray absorption spectroscopy study for perovskite cobaltite PrSrCoO (00.5) to understand Sr doping effect and magnetocaloric measurement for PrSrCoO to reveal the origin of magnetic anomaly at around 110 K. The extended X-ray absorption fine structure (EXAFS) measurements at the Co -edge suggest that the average valence value of Co ions increases, the interatomic distance of Co-O bonding decreases, and the local distortion of CoO octahedron increases as Sr is doped in PrCoO. The interatomic distance of Co-O bonding shrinks more greatly for the larger doping region. No temperature dependent electronic and structural changes were observed from Co -edge X-ray absorption spectra in the whole thermal range studied (17-300 K). The magnetocaloric effect of PrSrCoO indicates the change of magnetic structure at 110 K.

Short- and middle-ranges order structures of KNbO nanocrystals

Yoneda, Yasuhiro; Kunisada, Ryoichi*; Chikada, Tsukasa*; Ueno, Shintaro*; Fujii, Ichiro*; Nagata, Hajime*; Ohara, Koji*; Wada, Satoshi*

Japanese Journal of Applied Physics, 58(SL), p.SLLA03_1 - SLLA03_7, 2019/11

https://doi.org/10.7567/1347-4065/ab37e2

Electronic structure of UTe studied by photoelectron spectroscopy

Fujimori, Shinichi; Kawasaki, Ikuto; Takeda, Yukiharu; Yamagami, Hiroshi; Nakamura, Ai*; Homma, Yoshiya*; Aoki, Dai*

Journal of the Physical Society of Japan, 88(10), p.103701_1 - 103701_5, 2019/10

https://doi.org/10.7566/JPSJ.88.103701

Magnetic-impurity-induced modifications to ultrafast carrier dynamics in the ferromagnetic topological insulators SbVTe

Sumida, Kazuki*; Kakoki, Masaaki*; Reimann, J.*; Nurmamat, M.*; Goto, Shinichi*; Takeda, Yukiharu; Saito, Yuji; Kokh, K. A.*; Tereshchenko, O. E.*; Gdde, J.*; et al.

New Journal of Physics (Internet), 21(9), p.093006_1 - 093006_8, 2019/09

https://doi.org/10.1088/1367-2630/ab3ac6

Synchrotron radiation real-time photoelectron spectroscopy study on adsorption reactions of oxygen molecule at semiconductor surfaces

Yoshigoe, Akitaka

Hoshako, 32(4), p.185 - 198, 2019/07

Synchrotron radiation photoelectron spectroscopy is a beneficial technique for precise analysis of chemical states of solid surfaces. Owing to its high luminosity, it ensures availability of termed synchrotron radiation real-time photoelectron spectroscopy which enables "" observation of chemical reactions with gas molecules occurring at surfaces. In this review, oxygen adsorption reactions in the oxidation of silicon single crystal surfaces are focused. Through the demonstration of our research, the usefulness of synchrotron radiation real-time photoelectron spectroscopy to study molecular adsorption reactions at solid surfaces is briefly described and the future perspective would also be shown.

Electronic structure of the high- ferromagnetic semiconductor (Ga,Fe)Sb; X-ray magnetic circular dichroism and resonance photoemission spectroscopy studies

Sakamoto, Shoya*; Tu, N. T.*; Takeda, Yukiharu; Fujimori, Shinichi; Hai, P. N.*; Anh, L. D.*; Wakabayashi, Yuki K.*; Shibata, Goro*; Horio, Masafumi*; Ikeda, Keisuke*; et al.

Physical Review B, 100(3), p.035204_1 - 035204_8, 2019/07

https://doi.org/10.1103/PhysRevB.100.035204

Mass transport in the PdCu phase structures during hydrogen adsorption and absorption studied by XPS under hydrogen atmosphere

Tang, J.*; Yamamoto, Susumu*; Koitaya, Takanori*; Yoshigoe, Akitaka; Tokunaga, Takuma*; Mukai, Kozo*; Matsuda, Iwao*; Yoshinobu, Jun*

Applied Surface Science, 480, p.419 - 426, 2019/06

https://doi.org/10.1016/j.apsusc.2019.02.180

Mass transports during hydrogen adsorption and absorption processes of PdCu alloys that has advantages of higher hydrogen diffusivity and economically lower-cost than the other Pd-alloys were studied. The research was made with a comparison of the well-known ordered phase of the bcc structure (the B2 phase) and a mixed phase of the fcc and B2 structures. ultrahigh vacuum X-ray photoelectron spectroscopy and ambient pressure X-ray photoelectron spectroscopy using synchrotron radiation were carried out to trace the chemical states of the Pd and Cu atoms as a function of temperatures. It is elucidated that the initial adsorption and absorption processes were similar in the two phases, but a hydrogen diffusion rate to the bulk was higher in the ordered phase than in the mixed one. We found the dynamics of the Pd and Cu atoms during the hydrogen adsorption/absorption processes largely depend on temperature. In the hydrogen atmosphere, the Pd atoms segregate at the surface below 373 K and Cu atoms segregate at the surface above 373 K. The present results agree well with the previous theoretical calculations and, thus, provide appropriate inputs toward developments of the hydrogen permeation materials.