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Tsutsui, Nao; Ban, Yasutoshi; Suzuki, Hideya*; Nakase, Masahiko*; Ito, Sayumi*; Inaba, Yusuke*; Matsumura, Tatsuro; Takeshita, Kenji*
Analytical Sciences, 36(2), p.241 - 246, 2020/02
Times Cited Count：22 Percentile：81.93(Chemistry, Analytical)To investigate the effective separation of actinides (Ans) from lanthanides (Lns), single-stage batch extraction experiments were performed with a novel extractant, tetradodecyl-1,10-phenanthroline-2,9-diamide (TDdPTDA) with various diluents such as 3-nitrobenzotrifluoride (F-3), nitrobenzene, and 
-dodecane for Am, Cm, and Lns. The extraction kinetics with TDdPTDA was rapid enough to perform the actual extraction flow sheet. The slopes of the distribution ratio versus TDdPTDA concentration and the distribution ratio versus nitric acid concentration were similar for F-3 and nitrobenzene systems but different from -dodecane system. These differences were attributed to the characteristics of the diluents. This study reveals high distribution ratios of Am (
) and Cm ( 
) for TDdPTDA, with the high separation factors (
s) of Am from Lns enough for their separation.
edgeIshii, Kenji*; Toyama, Takami*; Asano, Shun*; Sato, Kentaro*; Fujita, Masaki*; Wakimoto, Shuichi; Tsutsui, Kenji*; Sota, Shigetoshi*; Miyawaki, Jun*; Niwa, Hideharu*; et al.
Physical Review B, 96(11), p.115148_1 - 115148_8, 2017/09
Times Cited Count：29 Percentile：77.61(Materials Science, Multidisciplinary)Tsutsui, Kenji; Kaneshita, Eiji*; Toyama, Takami*
Physical Review B, 92(19), p.195103_1 - 195103_5, 2015/11
Times Cited Count：2 Percentile：9.78(Materials Science, Multidisciplinary)Nonresonant inelastic X-ray scattering (NIXS) is a possible tool to detect charge excitations in electron systems. In addition, multipole transitions at high-momentum-transfer region open a new possibility to determine orbital-selective electronic excitations in multi-orbital itinerant 3
electron systems. As a theoretical example, we chose the antiferromagnetic state of iron arsenides and demonstrate that the orbital-selective excitations are detectable by choosing appropriate momentum transfer in NIXS. We propose that both NIXS and resonant inelastic X-ray scattering are complementary to each other for fully understanding the nature of orbital excitations in multi-orbital itinerant electron systems.
Toyama, Takami*; Tsutsui, Kenji; Mori, Michiyasu; Sota, Shigetoshi*; Yunoki, Seiji*
Physical Review B, 92(1), p.014515_1 - 014515_8, 2015/07
Times Cited Count：14 Percentile：52.17(Materials Science, Multidisciplinary)Resonant inelastic X-ray scattering (RIXS) tuned for Cu 
edge is a possible tool to detect charge excitations in cuprate superconductors. We theoretically investigate the possibility for observing a collective charge excitation by the RIXS. The RIXS process via the intermediate state inevitably makes the spectral weight of charge excitation stronger in electron doping than in hole doping. Electron-hole asymmetry also appears in dynamical charge structure factor, showing a new enhanced small-momentum low-energy mode in electron doping. These facts indicate a possibility of detecting the new charge mode by RIXS in electron-doped systems.
Tsutsui, Kenji; Toyama, Takami*; Maekawa, Sadamichi
JPS Conference Proceedings (Internet), 3, p.017008_1 - 017008_6, 2014/06
Impurity substitution for copper in high-Tc cuprate superconductors has attracted much attention. For Ni substitution, it has been argued from several experiments that hole carriers are strongly localized at around Ni sites. We have demonstrated theoretically that a hole can be bound in the NiO
plaquette forming the Zhang-Rice doublet. In this study, we examine the interaction between the Zhang-Rice doublet and hole carriers. We carry out the numerically exact diagonalization on small clusters of the d-p model with a Ni impurity site and calculate the resonant inelastic X-ray scattering spectra for Ni K-edge.
Sugimoto, Kodai*; Toyama, Takami*; Kaneshita, Eiji*; Tsutsui, Kenji
Journal of the Korean Physical Society, 63(3), p.632 - 635, 2013/08
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)Cr is the representative material of multi-orbital antiferromagnetism. We numerically calculate the band structure and density of states in commensurate antiferromagnetic Cr by multi-orbital Hubbard model with mean-field approximation. The result is adopted to the calculation of optical conductivity. The spectra of the optical conductivity is consistent with experimental data, and this promises the validity of our model.
Sugimoto, Kodai*; Li, Z.*; Kaneshita, Eiji*; Tsutsui, Kenji; Toyama, Takami*
Physical Review B, 87(13), p.134418_1 - 134418_8, 2013/04
Times Cited Count：7 Percentile：33.24(Materials Science, Multidisciplinary)We theoretically investigate spin dynamics and L-edge resonant inelastic X-ray scattering (RIXS) of chromiumwith commensurate spin-density wave (SDW) order, based on a multiband Hubbard model. Obtaining the ground state with the SDW mean-field approximation, we calculate the dynamical spin susceptibility by using random-phase approximation. We find that a collectivespin-wave excitation hardly damps up to 0.6 eV. Above the energy, the excitation overlaps individual particle-hole excitations, leading to broad spectral weight.
Tsutsui, Kenji; Toyama, Takami*; Koshibae, Wataru*; Maekawa, Sadamichi
Journal of Physics; Conference Series, 400(3), p.032105_1 - 032105_4, 2012/12
Times Cited Count：1 Percentile：46.41(Physics, Applied)The two-dimensional nickelate La
Sr
NiO
has received special attention as a reference system of high-
cuprates. The undoped nickelate (
=0) has the charge-transfer gap in the optical conductivity. Upon doping of holes, a broad spectrum appears in the gap. We have shown theoretically that the broad spectrum comes from excitations to the low spin states. In the Ni -edge resonant inelastic X-ray scattering (RIXS) measurement, the momentum-resolved charge excitations are obtained. In this study, we examine theoretically the RIXS spectra on nickelates by using numerically exact diagonalization techniques on the two-band Hubbard model. We also calculate other spectra such as the dynamical charge density function and discuss what excitations appear in the RIXS spectrum.
Cu
N
O as seen via resonant inelastic X-ray scatteringIshii, Kenji; Tsutsui, Kenji; Ikeuchi, Kazuhiko*; Jarrige, I.; Mizuki, Junichiro; Hiraka, Haruhiro*; Yamada, Kazuyoshi*; Toyama, Takami*; Maekawa, Sadamichi; Endo, Yasuo*; et al.
Physical Review B, 85(10), p.104509_1 - 104509_5, 2012/03
Times Cited Count：3 Percentile：14.86(Materials Science, Multidisciplinary)Tsutsui, Kenji; Toyama, Takami*; Maekawa, Sadamichi
Journal of Physics and Chemistry of Solids, 72(5), p.354 - 357, 2011/05
Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)We carry out the numerically exact diagonalization on small clusters of the d-p model with a Ni impurity site to simulate a resonant inelastic X-ray scattering spectra, as well as the single-particle excitation ones. We propose the resonant inelastic X-ray scattering experiment for Ni K edge to confirm the hole binding around the Ni impurity.
Tsutsui, Kenji; Toyama, Takami*; Maekawa, Sadamichi*
Physica C, 470(Suppl.1), p.S232 - S233, 2010/12
Times Cited Count：0 Percentile：0(Physics, Applied)The spectra of the Cu -edge Resonant inelastic X-ray scattering on the ladder cuprates are calculated by using the exact diagonalization method. So far it has been suggested that the momentum-dependence of the spectra on the ladder system is related with the formation of the spin singlet in the ground state. It has also revealed that the stabilization of the spin singlet strongly depends on the sign of the diagonal hopping of holes. In this study, in order to clarify the relationship between the spectra and the formation of the singlet state, the dependence of the spectra on the diagonal hopping of holes is examined. We find that the feature of the spectra is actually changed by the hopping and conclude that the resonant inelastic X-ray scattering can reveal the formation of the spin singlet state in the ladder system.
Cu
Ni
OIshii, Kenji; Ikeuchi, Kazuhiko*; Jarrige, I.; Mizuki, Junichiro; Hiraka, Haruhiro*; Yamada, Kazuyoshi*; Tsutsui, Kenji; Toyama, Takami*; Maekawa, Sadamichi*; Endo, Yasuo*; et al.
Physica C, 470(Suppl.1), p.S155 - S157, 2010/12
Times Cited Count：0 Percentile：0(Physics, Applied)
Cu
O
studied by resonant inelastic X-ray scatteringYoshida, Masahiro; Ishii, Kenji; Ikeuchi, Kazuhiko*; Jarrige, I.; Murakami, Yoichi*; Mizuki, Junichiro; Tsutsui, Kenji; Toyama, Takami*; Maekawa, Sadamichi*; Kudo, Kazutaka*; et al.
Physica C, 470(Suppl.1), p.S145 - S146, 2010/12
Times Cited Count：4 Percentile：21.9(Physics, Applied)
superconductorsTsutsui, Kenji; Toyama, Atsushi*; Toyama, Takami*; Maekawa, Sadamichi*
Journal of Physics and Chemistry of Solids, 69(12), p.3365 - 3368, 2008/12
Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)Substitution of impurities Zn and Ni for Cu in high- superconductors has attracted much attention. The recent neutron scattering experiment show that Ni doping traps holes in the vicinity of Ni sites. We theoretically examine the electronic state with impurity based on the 
model where impurity Zn and Ni 3 orbitals are explicitly treated. We carry out the numerically exact diagonalization method on small cluster. We find the region where a hole is trapped in the Ni site so that the effective hole concentration decreases and the ground state has strong antiferromagnetic correlations, as indicated from the experimental study.
cuprates studied by resonant inelastic X-ray scatteringIshii, Kenji; Hoesch, M.*; Inami, Toshiya; Kuzushita, Kaori*; Owada, Kenji; Tsubota, Masami; Murakami, Yoichi; Mizuki, Junichiro; Endo, Yasuo; Tsutsui, Kenji*; et al.
Journal of Physics and Chemistry of Solids, 69(12), p.3118 - 3124, 2008/12
Times Cited Count：3 Percentile：18.1(Chemistry, Multidisciplinary)CuOIshii, Kenji; Tsutsui, Kenji*; Toyama, Takami*; Inami, Toshiya; Mizuki, Junichiro; Murakami, Yoichi*; Endo, Yasuo*; Maekawa, Sadamichi*; Kudo, Kazutaka*; Koike, Yoji*; et al.
Physical Review B, 76(4), p.045124_1 - 045124_7, 2007/07
Times Cited Count：20 Percentile：63.37(Materials Science, Multidisciplinary)(La,Sr,Ca)CuO is an attractive material in connection with high-
superconductivity because Sr
Ca
CuO becomes a superconductor under high pressure without the CuO planes. We present RIXS at the Cu -edge of (La,Sr,Ca)CuO focusing on the momentum dependence of interband excitation across the Mott gap and the intraband excitation below the gap as a function of hole concentration. The experimental results are consistent with the theoretical predictions.
Seo, Hitoshi; Tsutsui, Kenji*; Ogata, Masao*; Merino, J.*
Journal of the Physical Society of Japan, 75(11), p.114707_1 - 114707_8, 2006/11
Times Cited Count：18 Percentile：67.21(Physics, Multidisciplinary)Effects of geometrical frustration in low-dimensional charge ordering systems are theoretically studied, mainly focusing on dynamical properties. We treat extended Hubbard models at quarter-filling, where the frustration arises from competing charge ordered patterns favored by different intersite Coulomb interactions, which are effective models for various charge transfer-type molecular conductors and transition metal oxides. From previous studies, charge ordered insulating states are known to be unstable in the frustrated region, resulting in a robust metallic phase even when the interaction strenghs are strong. By applying the Lanczos exact diagonalization to finite-size clusters, we have found that fluctuations of different charge order patterns exist in the frustration-induced metallic phase, showing up as characteristic low energy modesin dynamical correlation functions.
Cu
O
studied by resonant inelastic X-ray scatteringIshii, 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
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.
Ce
CuO (x=0, 0.075, and 0.15) studied by Resonant inelastic X-ray scatteringIshii, Kenji; Tsutsui, Kenji*; Endo, Yasuo*; Toyama, Takami*; Maekawa, Sadamichi*; Hoesch, M.; Kuzushita, Kaori; Inami, Toshiya; Tsubota, Masami; Yamada, Kazuyoshi*; et al.
AIP Conference Proceedings 850, p.403 - 404, 2006/09
We report a resonant inelastic X-ray scattering (RIXS) study of charge excitations in the electron-doped high- superconductor Nd
Ce
CuO. 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.
CeCuO; A Resonant inelastic X-ray scattering studyIshii, 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
Times Cited Count：72 Percentile：89.18(Physics, Multidisciplinary)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.
