Structural aspects of the superionic conduction mechanism in Ag-GeSe glasses

Stellhorn, J. R.*; Hosokawa, Shinya*; Pilgrim, W.-C.*; Kawakita, Yukinobu; Kamimura, Kenji*; Kimura, Koji*; Blanc, N.*; Boudet, N.*

Zeitschrift fr Physikalische Chemie, 230(3), p.369 - 386, 2016/03

https://doi.org/10.1515/zpch-2015-0667

Momentum dependence of Mott gap excitations in optimally doped YBaCuO studied by resonant inelastic X-ray scattering

Ishii, Kenji; Tsutsui, Kenji*; Endo, Yasuo*; Toyama, Takami*; Kuzushita, Kaori; Inami, Toshiya; Owada, Kenji; Maekawa, Sadamichi*; Masui, Takahiko*; Tajima, Setsuko*; et al.

AIP Conference Proceedings 850, p.445 - 446, 2006/09

https://doi.org/10.1063/1.2354776

Mott gap excitations in the optimally doped high- superconductor YBaCuO ( = 93 K) have been studied by the resonant inelastic X-ray scattering method. Anisotropic spectra in the -plane are observed in a twin-free crystal. The excitation from the one-dimensional CuO chain is enhanced at 2 eV near the zone boundary of the direction, while the excitation from the CuO plane is broad at 1.5-4 eV and almost independent of the momentum transfer. Theoretical calculation based on the one-dimensional and two-dimensional Hubbard model reproduces the observed spectra when different values of the on-site Coulomb energy are assumed. The Mott gap of the CuO chain site is found to be much smaller than that of the CuO plane site.

Resonant magnetic X-ray scattering study of UPdAl

Ishii, Kenji; Kuzushita, Kaori; Murakami, Yoichi; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika

Journal of the Physical Society of Japan, 75(Suppl.), p.102 - 104, 2006/08

UPdAl is an attractive material because of the coexistence of the antiferromagnetic order below = 14.5 K and superconductivity below = 2 K. In order to discuss the coupling between magnetism and superconductivity by resonant magnetic X-ray scattering (RMXS), nature of the resonance at each absorption edge should be clarified before the measurements across . Therefore we performed RMXS study from U to edge at . In addition to a huge resonance at -edge, we observed a resonant feature at -edge which corresponds to the transition from to orbitals, while resonance at -edge and -edge is rather small.

Momentum dependence of charge excitations in the electron-doped superconductor NdCeCuO; A Resonant inelastic X-ray scattering study

Ishii, Kenji; Tsutsui, Kenji*; Endo, Yasuo*; Toyama, Takami*; Maekawa, Sadamichi*; Hoesch, M.; Kuzushita, Kaori; Tsubota, Masami; Inami, Toshiya; Mizuki, Junichiro; et al.

Physical Review Letters, 94(20), p.207003_1 - 207003_4, 2005/05

https://doi.org/10.1103/PhysRevLett.94.207003

We report a resonant inelastic X-ray scattering (RIXS) study of charge excitations in the electron-doped high- superconductor NdCeCuO. The intraband and interband excitations across the Fermi energy are separated for the first time by tuning the experimental conditions properly to measure charge excitations at low energy. A dispersion relation with -dependent width emerges clearly in the intraband excitation, while the intensity of the interband excitation is concentrated around 2 eV near the zone center. The experimental results are consistent with theoretical calculation of the RIXS spectra based on the Hubbard model.

Charge-order pattern of the low-temperature phase from a monoclinic single domain of NaVO uniquely determined by resonant X-ray scattering

Owada, Kenji; Fujii, Yasuhiko; Katsuki, Yuya*; Muraoka, Jiro*; Nakao, Hironori*; Murakami, Yoichi; Sawa, Hiroshi*; Ninomiya, Emi*; Isobe, Masahiko*; Ueda, Yutaka*

Physical Review Letters, 94(10), p.106401_1 - 106401_4, 2005/03

https://doi.org/10.1103/PhysRevLett.94.106401

The present resonant X-ray scattering has been performed on a monoclinically-split single domain of NaVO. The observation of a critically enhanced contrast between V and V ions has led us to the unequivocal conclusion of the charge-order pattern of low-temperature phase of NaVO below = 35 K. In spite of the possible four types of configuration of the zig-zag-type charge-order patterns in the -plane (A, A', B and B'), the stacking sequence along the -axis is determined as the AAA'A' type by comparison with model calculations. By assigning the A and A' configurations to Ising spins, one can reasonably explain the previously discovered "devil's staircase"-type behavior with respect to the modulation of layer-stacking sequences at high pressures and low temperatures, which clearly resembles the global phase diagram theoretically predicted by the ANNNI model.

Resonant inelastic X-ray scattering study of the hole-doped manganites LaSrMnO (, )

Ishii, Kenji; Inami, Toshiya; Owada, Kenji; Kuzushita, Kaori; Mizuki, Junichiro; Murakami, Yoichi; Ishihara, Sumio*; Endo, Yasuo*; Maekawa, Sadamichi*; Hirota, Kazuma*; et al.

Physical Review B, 70(22), p.224437_1 - 224437_6, 2004/12

https://doi.org/10.1103/PhysRevB.70.224437

Electronic excitations in the hole doped manganese oxides (LaSrMnO, and ) have been elucidated by using the resonant inelastic X-ray scattering (RIXS) method. A doping effect in the strongly correlated electron systems has been observed for the first time. The scattering spectra show that a salient peak appears in low energies indicating the persistence of the Mott gap. At the same time, the energy gap is partly filled by doping holes and the spectral weight energy shifts toward lower energies. The excitation spectra show little change in the momentum space as is in undoped LaMnO. On the other hand, the scattering intensities in the low energy excitations of are anisotropic in temperature dependence, which indicates an anisotropy of magnetic interaction and underlying effect of the orbital.

Interference between thomson scattering and resonant scattering in X-ray diffraction from CeB

Nagao, Tatsuya*; Igarashi, Junichi

Journal of the Physical Society of Japan, 72(9), p.2381 - 2384, 2003/09

https://doi.org/10.1143/JPSJ.72.2381

We examine the mechanism of the X-ray diffraction process by including the Thomson scattering (TS) term in addition to the resonant X-ray scattering (RXS) term near the Ce L absorption edge in the antiferroquadrupole (AFQ) ordering phase of CeB. Assuming the AFQ order in the 4f states but without any lattice distortion, we obtain the TS intensity comparable to the RXS intensity, owing to the anisotropic charge distribution of 4f states. The present calculation reproduces well the interference pattern between the TS and RXS terms for the (5/2,3/2,3/2) spot observed in the recent experiment. The result suggests that the TS signal as well as the main peak of the RXS signal are a direct reflection of the AFQ order in CeB.

Mechanism of resonant X-ray scattering in DyBC

Nagao, Tatsuya*; Igarashi, Junichi

Physica B; Condensed Matter, 329-333(Part2), p.628 - 630, 2003/05

https://doi.org/10.1016/S0921-4526(02)02531-0

For elucidating the relation between the resonant X-ray scattering (RXS) signal and the orbital order, we calculate the RXS spectra near the Dy L absorption edge in DyBC, in the antiferro-quadrupole (AFQ) ordering phase. Using a microscopic model that the 4f states of Dy are atomic while the 5d states form an energy band with a reasonable density of states, we obtain sufficient RXS intensities on the AFQ superlattice spot assuming the quadrupole order in the 4f states but without any lattice distortion, in good agreement with the recent experiment. The present result demonstrates the mechanism that the intensity is brought about by the modulation of 5d states through the anisotropic term of the 5d-4f Coulomb interaction.

Magnetic resonant X-ray scattering in KCuF

Takahashi, Manabu*; Usuda, Manabu; Igarashi, Junichi

Physical Review B, 67(6), p.064425_1 - 064425_7, 2003/02

https://doi.org/10.1103/PhysRevB.67.064425

We study the magnetic resonant X-ray scattering (RXS) spectra around the K edge of Cu in KCuF on the basis of an ab initio calculation. We use the full-potential linearlized augumented plane wave method in the LDA+U scheme, and introduce the lattice distortion as inputs of the calculation. We obtain finite intensity on magnetic superlattice spots by taking account of the spin-orbit interaction. We also calculate the RXS intensity on orbital superlattice spots. It is found that the intensity increases with increasing Jahn-Teller distortion.