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Ga
and NpGaMetoki, Naoto
Journal of the Physical Society of Japan, 75(Suppl.), p.24 - 29, 2006/08
no abstracts in English
SiHonda, Fuminori; Metoki, Naoto; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.121 - 123, 2006/08
no abstracts in English
Si studied by neutron scatteringKaneko, Koji; Metoki, Naoto; Bernhoeft, N.*; Matsuda, Tatsuma; Haga, Yoshinori; Yasuda, Takashi*; Takeuchi, Tetsuya*; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.177 - 179, 2006/08
no abstracts in English
SR studies of Pu metal and the Pu-based superconductor PuCoGa
Heffner, R. H.; Bauer, E. D.*; Chung, B.*; Fluss, M. J.*; Higemoto, Wataru; Ito, Takashi; MacLaughlin, D. E.*; Morales, L. A.*; Morris, G. D.*; Oishi, Kazuki; et al.
Journal of the Physical Society of Japan, 75(Suppl.), p.14 - 19, 2006/08
no abstracts in English
; Comparison with UO
from 
O-NMRTokunaga, Yo; Homma, Yoshiya*; Kambe, Shinsaku; Aoki, Dai*; Ikushima, Kenji; Sakai, Hironori; Ikeda, Shugo; Yamamoto, Etsuji; Nakamura, Akio; Shiokawa, Yoshinobu; et al.
Journal of the Physical Society of Japan, 75(Suppl.), p.33 - 35, 2006/08
The low-temperature phase transition in NpO has attracted much attention as a promising candidate for a new class of phase transitions associated with octupolar degrees of freedom. In order to elucidate the nature of this exotic phase transition in NpO, we have initiated the first O-NMR measurements on this system using a powder sample. From the O-NMR spectrum, the occurrence of two inequivalent oxygen sites has been confirmed below 
= 26 K. It has also been shown that the temperature and field dependence of the O NMR spectrum can be understood by considering an unconventional hyperfine interaction between the O nuclear spins and field-induced antiferromagnetic moments arising from the longitudinal triple-
antiferro-quadrupolar order. These NMR results give strong evidence for the occurrence of the longitudinal triple- multipole structure in NpO. We will also discuss our recent O-NMR results in a single crystal.
-electron systemsKubo, Katsunori; Hotta, Takashi
Journal of the Physical Society of Japan, 75(Suppl.), p.232 - 237, 2006/08
Novel magnetism and exotic superconductivity in actinide compounds have attracted much attention. Among several interesting properties of actinide materials, we review two topics from a microscopic view point. One is multipole ordering in cubic systems, such as peculiar magnetism in NpO. The other topic is a potential role of multipole fluctuations in tetragonal systems. Such fluctuations characteristic to -electron systems may relate to the superconductivity of the so-called Pu-115 materials (PuCoGa and PuRhGa) with relatively high transition temperatures.
Si probed by muon spin relaxationHigemoto, Wataru; Haga, Yoshinori; Matsuda, Tatsuma; Onuki, Yoshichika; Koda, Akihiro*; Saha, S. R.*; Oishi, Kazuki; Kadono, Ryosuke*
Journal of the Physical Society of Japan, 75(Suppl.), p.180 - 182, 2006/08
We report on the Magnetism, magnetic penetration depth and the Knight shift in polycrystalline sample of CePtSi by means of muon spin rotation and relaxation method. The appearance of the internal field under the zero magnetic field in whole volume of the specimen, was observed, which indicating clear evidence of antiferromagnetism. The muon Knight shift was measured down to 20mK at 17kOe. Three different frequencies are seen in the muon spin rotation spectra, which depend on the temperature. The symmetry of the superconducting Cooper pair will be discussed.
BFujimoto, Tatsuya; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Walstedt, R. E.; Ikeda, Shugo; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.113 - 115, 2006/08
The low-dimensional systems exhibit wide-variety of physical properties. In the antiferromagnetic triangular lattice, for instance, resonating valence bond state is expected, furthermore, in one-dimensional (1D) systems, metal-insulator transition (Peierls transition) occurs due to charge-lattice couplings. Up to now, the study of low-dimensional systems has been mostly performed in oxides and organic compounds, but it is rare in the rare-earth and actinide intermetallics. To looking for the novel low-dimensionality in -electron systems, we focused on the UIrB, and NMR measurement was carried out. From Knight shift and nuclear spin-lattice relaxation rates, ferromagnetic correlations develop above 50 K, but below 50 K, the emergence of antiferromagnetic correlations was clarified along with the saturation of ferromagnetic correlations. The possible model to explain the obtained result is nesting effect on the 1D Fermi surface, and it is expected that UIrB will be the typical compound to investigate the physical properties of 1D -electrons systems.
Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Fujimoto, Tatsuya; Kato, Harukazu; Walstedt, R. E.; Ikeda, Shugo; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.127 - 129, 2006/08
Recently, new superconductors have been discovered in Pu-based HoCoGa(115) structure compounds: PuCoGa (
) and PuRhGa (
). The discovery has stimulated a lot of interest in actinide compounds. We report NMR measurements on a high-quality single crystal sample of the non-superconducting U- and Np-based 115 compounds. In order to elucidate universal magnetic properties and the origin of superconductivity in the 115 families, spin-lattice relaxation and Knight shift measurements have been performed systematically in the non-superconducting 115 compounds. Comparison of dynamical properties with the superconducting Pu115 compounds will be presented.
and LuCoGaMatsuda, Tatsuma; Haga, Yoshinori; Sakai, Hironori; Ikeda, Shugo; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.85 - 87, 2006/08
Recently quasi-two-dimensional electron state in rare earth and actinide compounds with HoCoGa-type tetragonal crystal structure was attracted a lot attention in relation to heavy fermion superconductivity observed in CeCoIn, CeIrIn and PuCoGa. In order to elucidate the role of electron in these compounds, it is necessary to compare their electronic state with that of lanthanum and thorium compounds which do not possess the -electrons. The number of valence electrons in the thorium compound is the same as that of the corresponding 4
-itinerant cerium compound. We have recently tried to make thorium 115 compounds by indium flux method and have succeeded in discovering the new material of ThRhIn. Crystal structure and quality were confirmed by X-ray diffraction, fluorescent X-ray analysis and EPMA. The lattice parameters were determined to be 4.681(6) 
and 
, respectively. The positional parameter 
of In(4
) site was also determined to be 
.
by ac calorimetryTateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma; Ikeda, Shugo; Nakashima, Miho*; Thamizhavel, A.*; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.174 - 176, 2006/08
We have investigated the physical properties of Heavy Fermion superconductors by the ac calorimetry under high pressure using a thermocouple. The method is powerful tool since the high sensitive measurement of the heat capacity is possible and the precise pressure dependence of transition temperatures such as the superconducting transition can be determined. In this conference, I would like to report our investigations on the heavy fermion superconductors CePtSi, CeNiGe and UIr. We have made pressure phase diagram of these compounds and discuss the relation between the magnetism and superconductivity.
Ikeda, Shugo; Sakai, Hironori; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; Shiokawa, Yoshinobu; Haga, Yoshinori; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.116 - 118, 2006/08
no abstracts in English
AlIshii, 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.
Okane, Tetsuo; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Okamoto, Jun*; Mamiya, Kazutoshi*; Muramatsu, Yasuji*; Fujimori, Atsushi; Ochiai, Akira*; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 75(Suppl.), p.105 - 106, 2006/08
no abstracts in English
Fujimori, Shinichi; Terai, Kota; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Kobayashi, Keisuke; Fujimori, Atsushi; Yamagami, Hiroshi*; Ikeda, Shugo; Matsuda, Tatsuma; et al.
Journal of the Physical Society of Japan, 75(Suppl.), p.99 - 101, 2006/08
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)In the present study, we have performed SX-ARPES experiments on some heavy Fermion (HF) uranium compounds such as UPdAl using soft X-ray synchrotron radiation from BL23SU of SPring-8. UPdAl is an HF uranium compound which has transitions into an antiferromagnetic phase at 
K and into a superconducting phase at 
=2 K. To describe the various properties of this compound, the dual model for U 5 states is proposed. In this model, two of the three U 5f states are in a localized state while the third electron has delocalized character. We have obtained U 5f sensitive band structure of UPdAl by SX-ARPES, and the results are compared with this scenario. Temperature dependence of the U 5 electronic structure in this compound is also discussed.
; A Theoretical approach to Pr-based compound from itinerant pictureMaehira, Takahiro*; Hotta, Takashi
Journal of the Physical Society of Japan, 75(Suppl.), p.262 - 265, 2006/08
We calculate energy band structure and the Fermi surface of PrCoIn by using a self-consistent relativistic linear augmented-plane-wave method with the exchange and correlation potential in a local density approximation. It is found in common with other rare-earth and actinide compounds with the HoCoGa-type tetragonal crystal structure that the energy bands in the vicinity of the Fermi level are mainly due to the large hybridization between Pr 
and In 
electrons. The Fermi surface is found to consist of a large quasi-two-dimensional hole sheet. We discuss the comparison of our Fermi surface with experimental results on PrCoIn.
around the critical pressureSettai, Rikio*; Kubo, Tetsuo*; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika; Harima, Hisatomo*
Journal of the Physical Society of Japan, 75(Suppl.), p.167 - 169, 2006/08
We have studied a change of the Fermi surface in an antiferromagnet CeIn via the de Haas-van Alphen experiment under pressure up to 2.9 GPa. In the pressure region P
= 2.6 GPa, we have observed a large main Fermi surface named 
, which indicates that the electronic state of 4 electron in CeIn changes from localized to itinerant at . The cyclotron effective mass 
of this main Fermi surface is extremely enhanced around .
-electron systemsOnishi, Hiroaki; Hotta, Takashi
Journal of the Physical Society of Japan, 75(Suppl.), p.266 - 269, 2006/08
In order to clarify multipole correlations in -electron systems, we investigate a one-dimensional -electron model based on a 
- coupling scheme by exploiting a density-matrix renormalization group method. We discuss the effect of a crystalline electric field and the dependence on the change of -electron numbers in detail.
Shishido, Hiroaki*; Yamamoto, Etsuji; Haga, Yoshinori; Ikeda, Shugo; Nakashima, Miho*; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.119 - 120, 2006/08
Times Cited Count：1 Percentile：10.62(Physics, Multidisciplinary)no abstracts in English
Haga, Yoshinori; Aoki, Dai*; Yamagami, Hiroshi*; Matsuda, Tatsuma; Nakajima, Kunihisa; Arai, Yasuo; Yamamoto, Etsuji; Nakamura, Akio; Homma, Yoshiya*; Shiokawa, Yoshinobu*; et al.
Journal of the Physical Society of Japan, 75(Suppl.), p.4 - 9, 2006/08
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)The discovery of the high-temperature in PuCoGa and PuRhGa promoted us to extend our research to other actinide compounds. We recently succeeded in growing single crystals of PuRhGa and performed magnetic measurements and NMR study both in the normal and superconducting states in collaboration with Tohoku university. The magnetic susceptibility consists of Curie-Weiss and temperature-independent terms where the former corresponds to the paramagnetic effective moment close to the 5
configuration. On the other hand, the superconducting upper critical field is anisotropic. It is explained by the anisotropic mass model with an effective mass ratio of 4, indicating the presence of quasi-two-dimensional Fermi surfaces. These characteristics are reminiscent of those observed in CeCoIn.
