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electron state in the heavy fermion superconductor NpPd
Al
Metoki, Naoto; Aoki, Dai*; Griveau, J.-C.*; Otsuki, Junya*
Journal of the Physical Society of Japan, 89(2), p.024707_1 - 024707_6, 2020/02
Times Cited Count：3 Percentile：22.83(Physics, Multidisciplinary)The pseudo triplet ground state in the heavy-fermion superconductor NpPdAl was concluded. The magnetic susceptibility 
can be reproduced by the singlet ground state 
with the main component of 
and the first excited doublet 
dominated by 
at 
,K. The magnetization curve can be explained from the effective local hamiltonian for pseudo spin 
=1 with 
(
) equivalent to the quadrupole operator 
. The specific heat can be described with the Kondo model normalized to give the entropy R
, corresponding to the pseudo triplet state. The derived Kondo temperature 
,K comparable to the level splitting ,K indicates the contribution of the excited doublet to the possible multi-channel Kondo effect.
states in UPdAl and valence crossover in the Vicinity of Heavy-Fermion superconductivityMetoki, Naoto; Haga, Yoshinori; Yamamoto, Etsuji; Matsuda, Masaaki*
Journal of the Physical Society of Japan, 87(11), p.114712_1 - 114712_9, 2018/11
Times Cited Count：3 Percentile：24.98(Physics, Multidisciplinary)The localized 5 states with 5 (
) configuration of U
ion have been revealed in UPdAl. We found that the low-lying states are the same as PrPdAl flat orbitals with large 
are stabilized by a two-dimensional CEF potential in the unique crystal structure. The present study involves the valence crossover from tetravalent to trivalent in a series of AnPdAl, demonstrated by lattice and/or transport anomaly as well as many body effects in the vicinity of the boundary. The valence instability plays important role for the unusual heavy fermion superconductivity in NpPdAl.
Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Haga, Yoshinori; Yamamoto, Etsuji
Journal of the Physical Society of Japan, 83(11), p.114710_1 - 114710_6, 2014/11
Times Cited Count：2 Percentile：18.76(Physics, Multidisciplinary)
Ga NMR has been measured in the metallic ferromagnet UGa. The 
-dependence of the internal field at the Ga site has been determined and is found to coincide with that of the spontaneous magnetization. The electric field gradient (EFG) and transferred hyperfine coupling constant at the Ga site are found to be modified in the ferromagnetically ordered state, presumably due to a modification of the 
electronic state caused by the ferromagnetic ordering. The spin-lattice relaxation rate 
is enhanced due to ferromagnetic fluctuations around 
. The 5 magnetic moments are considered to be nearly localized in UGa, in spite of good metallic conduction.
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
Matsumura, Tatsuro; Takeshita, Kenji*
ACS Symposium Series, 933, p.261 - 273, 2006/07
Three TPEN isomers with different positon of nitrogen donor in pyridyl groups, t2pen, t3pen and t4pen, were synthesized and the extraction separation of Am(III) and Eu(III) with these ligands and a fatty acid, decanoic acid, was investigated. All isomers were similar in the complexation in the aqueous phase, such as the protonation and the formation of metal complex, however, they showed different extraction behavior of Am and Eu. The synergistic extraction effect for Am was observed for t2pen and the high separation factor about 100 was measured, when 1:2. The value is comparable to that for the extraction system with a famous nitrogen-donor extractant, BTP. On the other hand, the extractability of other isomers was very low and no separation of Am and Eu was observed. Only t2pen, in which nitrogen donor in pyridyl groups is positioned in the vicinity of the skeletal structure (N-C-C-N structure) of ligand, is available for the extraction separation of Am.
UO
; A Canted ferromagnet with double-perovskite related orthorhombic structureNakamura, Akio; Yoshii, Kenji
Physica B; Condensed Matter, 378-380, p.548 - 549, 2006/05
Times Cited Count：2 Percentile：11.63(Physics, Condensed Matter)BaUO with double-perovskite related orthorhombic structure has been prepared. The magnetic susceptibility measurement has revealed that this system undergoes successive magnetic transitions at 60 K and 19 K. Curie-Weiss analysis was consistent with the presence of U
in the distorted octahedral sites. The magnetization vs. magnetic field data at 2 K exhibited a clear hysteresis loop without saturation. These results suggest that this material is a canted ferromagnet.
SiHonda, Fuminori; Metoki, Naoto; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika
Journal of Physics; Condensed Matter, 18(2), p.479 - 492, 2006/01
Times Cited Count：21 Percentile：64.24(Physics, Condensed Matter)no abstracts in English
(T=Fe, Rh and Ni)Aoki, Dai*; Homma, Yoshiya*; Shiokawa, Yoshinobu; Sakai, Hironori; Yamamoto, Etsuji; Nakamura, Akio; Haga, Yoshinori; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan, 74(8), p.2323 - 2331, 2005/08
Times Cited Count：53 Percentile：84.39(Physics, Multidisciplinary)no abstracts in English
electrons and the Fermi surface properties in an enhanced Pauli paramagnet NpGe
Aoki, Dai*; Yamagami, Hiroshi*; Homma, Yoshiya*; Shiokawa, Yoshinobu; Yamamoto, Etsuji; Nakamura, Akio; Haga, Yoshinori; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan, 74(8), p.2149 - 2152, 2005/08
Times Cited Count：25 Percentile：71.91(Physics, Multidisciplinary)no abstracts in English
Ikeda, Shugo; Metoki, Naoto; Haga, Yoshinori; Kaneko, Koji; Matsuda, Tatsuma; Onuki, Yoshichika
Physica B; Condensed Matter, 359-361, p.1030 - 1032, 2005/06
Times Cited Count：1 Percentile：5.75(Physics, Condensed Matter)We have succeeded to grow a single crystal of uranium ternary intermetallic compound UPdGa by the Ga self-flux method. The magnetic susceptibility showed a weak temperature dependence and small anisotropy,consistent with an itinerant character of 5 electrons. We observed a clear drop in the susceptibility and electrical resistivity below the Neel temperature 
= 31 K. The magnetic structure was studied by means of a neutron diffraction measurement. We observed an antiferromagnetic peak with the propagation vector 
=[0,0,1/2]. The uranium 5 moment of 0.33
parallel to the 
-axis was found to order ferromagnetically in the basal -plane and coupled antiferromagnetically along the -axis.
Galatanu, A.; Haga, Yoshinori; Matsuda, Tatsuma; Ikeda, Shugo; Yamamoto, Etsuji; Aoki, Dai*; Takeuchi, Tetsuya*; Onuki, Yoshichika
Journal of the Physical Society of Japan, 74(5), p.1582 - 1597, 2005/05
Times Cited Count：40 Percentile：79.95(Physics, Multidisciplinary)We investigated the magnetic property of typical uranium compounds by measuring the magnetic susceptibility in an extended temperature range up to about 800 K. The magnetic susceptibility follows the Curie-Weiss law for a localized 5-electron compound UPd
and a ferromagnetic insulator UFe
P
. In most of the investigated compounds we observed a crossover effect of the 5 electrons from a low-temperature itinerant nature to a high-temperature localized one. This is found to be characteristic for ferromagnetic superconductors such as UGe and UIr, and also for antiferromagnets like USb or UNiSb. To assess an extension of this characteristic property in the uranium compounds we also investigated typical 5-itinerant compounds like UGa and UPtGa. The crossover effect is essentially important in heavy fermion compounds such as UPt, UPdAl and URuSi. Even in the paramagnetic compound of UB, the magnetic susceptibility is not temperature-independent, but approaches a 5-localized tendency at high temperatures. Since the samples were single crystals, we were also able to trace the evolution of the magnetic anisotropy. The high-temperature anisotropic susceptibility data were analyzed on the basis of the crystalline electric field scheme.
Tanaka, Kumiko; Hirata, Masaru; Sekine, Rika*
Journal of Nuclear and Radiochemical Sciences, 5(2), p.27 - 31, 2004/12
The relativistic discrete-variational Dirac-Fock-Slater (DV-DFS) method was performed to investigate the electronic structure of MgO doped with Pu or Am atoms. The differences between these systems, in particular, the participation of d-electrons and f-electrons in chemical bonding, were clarified by calculating their electronic structures. Substitution of actinide atoms was found to result in the effective charges of MgO becoming smaller, with a large charge transfer occurring as far as the second layer. It was also found that the bonding feature between the center atom and the surrounding oxygen atoms was extended to lower energy in the case of actinide (An) substituted systems. Moreover, the bonding characteristics were assigned; a bonding interaction for An6d-O2p and an anti-bonding for An5f-O2p near the HOMO level. These complex effects were found to dominate the strength of the covalent bonding between MgO and actinide atoms.
Mirvaliev, R.*; Watanabe, Masayuki; Matsumura, Tatsuro; Tachimori, Shoichi*; Takeshita, Kenji*
Journal of Nuclear Science and Technology, 41(11), p.1122 - 1124, 2004/11
Times Cited Count：23 Percentile：78.84(Nuclear Science & Technology)Transmutation is a technology aimed to reduce HLW from reprocessing process. Minor actinides in the HLW will be converted to short-lived nuclides. However, lanthanides in HLW adversely affects on the efficiency of the transmutation. It is well known that separating An(III) and Ln(III) is very difficult because of their similarity of chemical properties. Therefore, the separation is one of the essential subjects to establish the transmutation technology. Considerable efforts have been devoted to the development of new extractants for the separation. N,N,N',N'-tetrakis(2-methylpyridyl)ethylenediamine (TPEN) demonstrates 100-fold preference for Am(III) over Ln(III) between stability constants with the ions in the aqueous phase. We have reported that Am(III) was selectively extracted from the aqueous phase containing Ln(III) by TPEN in nitrobenzene system and synergistic system with TPEN and D2EHPA in octanol. This work presents our recent results that Am(III) is separated from Eu(III) by a synergistic extraction system with TPEN and decanoic acid diluted with 1-octanol.
ssbauer Isomer shifts and Structures of Neptunium compoundsSaeki, Masakatsu; Nakada, Masami; Kitazawa, Takafumi*
KURRI-KR-106, p.38 - 42, 2004/03
no abstracts in English
antiferromagnet UPtSiMetoki, Naoto; Koike, Yoshihiro; Haga, Yoshinori; Bernhoeft, N.*; Lander, G. H.*; Tokiwa, Yoshifumi; Onuki, Yoshichika
Acta Physica Polonica B, 34(2, Part2), p.979 - 982, 2003/02
no abstracts in English
and UPtGaTokiwa, Yoshifumi; Haga, Yoshinori; Metoki, Naoto; Nakamura, Akio; Ishii, Yoshinobu; Onuki, Yoshichika
Journal of Nuclear Science and Technology, 39(Suppl.3), p.210 - 213, 2002/11
no abstracts in English
Omichi, Toshihiko*; Arai, Yasuo
Journal of Nuclear Science and Technology, 39(Suppl.3), p.156 - 159, 2002/11
no abstracts in English
under pressureNakamura, Mitsutaka; Koike, Yoshihiro; Metoki, Naoto; Kakurai, Kazuhisa; Haga, Yoshinori; Lander, G. H.; Aoki, Dai*; Onuki, Yoshichika
Journal of Physics and Chemistry of Solids, 63(6-8), p.1193 - 1196, 2002/06
Times Cited Count：15 Percentile：58.24(Chemistry, Multidisciplinary)no abstracts in English
and UPtGaTokiwa, Yoshifumi; Haga, Yoshinori; Metoki, Naoto; Ishii, Yoshinobu; Onuki, Yoshichika
Journal of the Physical Society of Japan, 71(3), p.725 - 728, 2002/03
no abstracts in English
U Mssbauer spectroscopic study of UX(X=Ga, P, As, Sb)Tsutsui, Satoshi; Nakada, Masami; Nasu, Saburo*; Haga, Yoshinori; Homma, Tetsuo; Yamamoto, Etsuji; Tokiwa, Yoshifumi; Aoki, Dai*; Wi
niewski, P.*; Onuki, Yoshichika
Journal of the Physical Society of Japan, Vol.70, Supplement A, p.34 - 36, 2001/05
no abstracts in English
