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electronic state accompanied by unusual moment reorientation in NpRhGa
Jonen, Shintaro; Metoki, Naoto; Honda, Fuminori; Kaneko, Koji; Yamamoto, Etsuji; Haga, Yoshinori; Aoki, Dai*; Homma, Yoshiya*; Shiokawa, Yoshinobu; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.41 - 43, 2006/08
Elastic neutron scattering experiments have been carried out in order to reveal the magnetic structure and 5f electronic state of NpRhGa. This material exhibits two successive antiferromagnetic transition at T
= 36 K and T
= 33 K, respectively. A-type antiferromagnetic structure with the propagation vector q = (0 0 1/2) has been revealed below T. We found a remarkable change in the moment direction, namely the Np moment is parallel and perpendicular to the c-axis for T 
T T and T T, respectively. The magnetic moment exhibits a remarkable jump at T, indicating that the moment reorientation is associated with the change of 5f electronic state. The observed magnetic form factor indicates the dominant contribution of the orbital moment and revealed an itinerant character of the 5f electrons.
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.
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.
-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：10.81(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.
Ito, Takashi; Nishida, Nobuhiko*; Oishi, Kazuki; Higemoto, Wataru; Karaki, Yoshitomo*; Ishimoto, Hidehiko*
Journal of the Physical Society of Japan, 75(Suppl.), p.189 - 191, 2006/08
no abstracts in English
(C
H
O)(CHN)Nakamura, Akio; Nakada, Masami; Nakamoto, Tadahiro*; Kitazawa, Takafumi*; Takeda, Masuo*
Journal of the Physical Society of Japan, 75(Suppl.), p.146 - 148, 2006/08
no abstracts in English
observed by 
Np and 
Fe M
ssbauer spectroscopyHomma, Yoshiya*; Nasu, Saburo; Nakamura, Akio; Nakada, Masami; Aoki, Dai*; Metoki, Naoto; Yamamoto, Etsuji; Sakai, Hironori; Ikeda, Shugo; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 75(Suppl.), p.44 - 46, 2006/08
no abstracts in English
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 PuCoGaHeffner, 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.
