Jonen, Shintaro; Metoki, Naoto; Honda, Fuminori; Kaneko, Koji; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Haga, Yoshinori; Shiokawa, Yoshinobu; Onuki, Yoshichika
Physica B; Condensed Matter, 378-380, p.1018 - 1020, 2006/05
The magnetic structure of NpRhGa has been investigated by neutron scattering. NpRhGa exhibits two antiferromagnetic phases with transition temperatures at T = 36 K and T = 33 K. Neutron scattering experiments revealed an antiferromagnetic structure with propagation vector q = (0 0 1/2) for both, where the Np magnetic moments are oriented parallel to the c-axis for T T T and parallel to the  direction on basal plane for T T. At T the reorientation of magnetic moments is accompanied by a sudden increase of magnetic moments, indicative of the first order transition. The magnetic form factor revealed a dominant contribution of the orbital moments.
Metoki, Naoto; Kaneko, Koji; Raymond, S.*; Sanchez, J. P.*; Piekarz, P.*; Parlinski, K.*; Ole, A. M.*; Ikeda, Shugo; Matsuda, Tatsuma; Haga, Yoshinori; et al.
Physica B; Condensed Matter, 378-380, p.1003 - 1004, 2006/05
no abstracts in English
Matsuda, Tatsuma; Haga, Yoshinori; Shishido, Hiroaki*; Ikeda, Shugo; Harima, Hisatomo*; Settai, Rikio*; Onuki, Yoshichika
Physica B; Condensed Matter, 378-380, p.1021 - 1022, 2006/05
We have succeeded in growing a high-quality single crystal of ThIn with the cubic structure by the In-flux method and measured the de Haas-van Alphen (dHvA) effect. Several dHvA branches were observed, ranging from 9.0 10 to 9.37 10 Oe. The experimental results are compared to the dHvA results of CeIn under pressure of 2.7 GPa, together with the results of energy band calculations.
Honda, Fuminori; Metoki, Naoto; Kaneko, Koji; Jonen, Shintaro; Yamamoto, Etsuji; Aoki, Dai*; Shiokawa, Yoshinobu*; Shiokawa, Yoshinobu; Onuki, Yoshichika
Physica B; Condensed Matter, 378-380, p.1009 - 1010, 2006/05
no abstracts in English
Fujimoto, Tatsuya; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Walstedt, R. E.; Ikeda, Shugo; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika
Physica B; Condensed Matter, 378-380, p.997 - 998, 2006/05
We report B NMR results of a single crystal UIrB. The measurement was performed by Fast Fourier Transformation technique, because spectral line width is extremely narrow ( 10 kHz) and NMR occurs in quite limited r.f. band due to a good sample quality. From temperature variation of Knight shift and nuclear spin-lattice relaxation rate, the development of ferromagnetic correlations was clarified in the temperature range above K. On the other hand, the magnetic dynamics was changed into another novel state below ; ferromagnetic correlations are restrained, meanwhile antiferromagnetic correlations are newly emerged. To explain this characteristic ground state, the one-dimensional electrons state due to the unique structural lattice of UIrB was proposed.
Tokunaga, Yo; Homma, Yoshiya*; Kambe, Shinsaku; Aoki, Dai*; Sakai, Hironori; Yamamoto, Etsuji; Nakamura, Akio; Shiokawa, Yoshinobu; Walstedt, R. E.; Yasuoka, Hiroshi
Physica B; Condensed Matter, 378-380, p.929 - 930, 2006/05
We have initiated the first O-NMR measurements in the ordered state of NpO. From the O-NMR spectrum, we have confirmed the occurrence of two inequivalent oxygen sites below = 26 K. It has also been shown that the O-NMR spectrum in the ordered state 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.
Sakai, Hironori; Tokunaga, Yo; Fujimoto, Tatsuya; Kambe, Shinsaku; Walstedt, R. E.; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.
Physica B; Condensed Matter, 378-380, p.1005 - 1006, 2006/05
Ga NMR/NQR studies have been performed on a single crystal of the transuranium superconductor PuRhGa with =9 K. The spin-lattice relaxation rate reveals that PuRhGa is an unconventional superconductor having an anisotropic superconducting gap. Moreover, Korringa behavior () is observed in the normal state below 30 K. This result suggests that the superconductivity sets in after the formation of a Fermi liquid state in this compound.
Kubo, Katsunori; Hotta, Takashi
Physica B; Condensed Matter, 378-380, p.1081 - 1082, 2006/05
In order to investigate multipole ordering in -electron systems from a microscopic viewpoint, we study the so-called models on three kinds of lattices, simple cubic (sc), bcc, and fcc, based on a - coupling scheme with -electron hopping integrals through bonding. From the model, we derive an effective model for each lattice structure by using the second-order perturbation theory with respect to . By further applying mean-field theory to the effective model, we find a antiferro-quadrupole transition for the sc lattice, a antiferro-octupole transition for the bcc lattice, and a longitudinal triple- octupole transition for the fcc lattice.
Physica B; Condensed Matter, 378-380, p.51 - 53, 2006/05
In order to clarify what types of spin and orbital fluctuations dominate over low-temperature electronic properties of Pr-based filled skutterudites, we evaluate multipole susceptibility based on a multiorbital Anderson model constructed from a - coupling scheme. It is found that magnetic and quadrupole fluctuations are dominant at low temperatures. When we further include the effect of rattling as dynamical Jahn-Teller phonons, there remain quadrupole and octupole fluctuations, which may induce exotic superconducting pairing.
Onishi, Hiroaki; Hotta, Takashi
Physica B; Condensed Matter, 378-380, p.589 - 591, 2006/05
We investigate the ground-state property of an -orbital Hubbard model at quarter filling on a zigzag chain by exploiting the density matrix renormalization group method. When two orbitals are degenerate, the zigzag chain is decoupled to a doble-chain spin system to suppress the spin frustration due to the spatial anisotropy of the occupied orbital. On the other hand, when the level splitting is increased and the orbital anisotropy disappears, a characteristic change in the spin incommensurability is observed due to the revival of the spin frustration.
Okane, Tetsuo; Takeda, Yukiharu; Fujimori, Shinichi; Terai, Kota; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika
Physica B; Condensed Matter, 378-380, p.959 - 960, 2006/05
no abstracts in English
Kaneko, Koji; Metoki, Naoto; Matsuda, Tatsuma; Kuwahara, Keitaro*; Kogi, Masafumi*; Shiina, Ryosuke*; Mignot, J.-M.*; Gukasov, A.*; Bernhoeft, N.*
Physica B; Condensed Matter, 378-380, p.189 - 191, 2006/05
Neutron diffraction experiments under magnetic fields were carried out on the heavy fermion superconductor PrOsSb in order to reveal the origin of the field-induced ordered phase (FIOP) for [1,1,0]. The application of magnetic field induces the weak superlattice peaks with the ordering vector =(1,0,0) in FIOP, which is the same as for [0,0,1]. The observed superlattice reflections for [1,1,0] result from the antiferromagnetic component of +; the induced tiny antiferromagnetic moments orient parallel to the applied field. This result cannot be explained by magnetic interactions and strongly evidences the underlying AFQ order with as a primary order parameter. These facts clarify the dominant role of -type antiferroquadrupolar interaction in PrOsSb.
Fujimori, Shinichi; Terai, Kota; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Yamagami, Hiroshi*; Ikeda, Shugo; Matsuda, Tatsuma; et al.
Physica B; Condensed Matter, 378-380, p.995 - 996, 2006/05
Recently, photoemission experiments in soft X-ray region have attracted much attention due to their high sensitivities for bulk electronic structures of strongly correlated electron system. We have carried out the high-resolution photoemission experiments on some uranium compounds using soft X-ray synchrotron radiation from SPring-8 to understand their electronic structures. Bulk- and U 5-sensitive band structure and Fermi surface were obtained for itinerant U 5 compounds UFeGa and USb, and they are compared with the results of the band structure calculations treating U 5 states as being itinerant. In addition, we show the results of photoemission study on some heavy fermion compounds such as UPdAl and UNiAl. The temperature dependences of the U 5 electronic structure of UPdAl will be also reported.
Maehira, Takahiro*; Hotta, Takashi
Physica B; Condensed Matter, 378-380, p.1027 - 1028, 2006/05
By using a relativistic linear augmented-plane-wave method, we clarify energy band structure and the Fermi surfaces of recently synthesized thorium compound ThRhIn. We find several cylindrical Fermi surface sheets, which are similar to those of CeTIn (T=Ir and Co), PuTGa (T=Co and Rh), and AmCoGa. We discuss such similarity among the compounds including rare-earth or actinide ions with different electron numbers.
Thamizhavel, A.*; Sugitani, Ichiro*; Obiraki, Yoshiko*; Nakashima, Miho*; Okuda, Yusuke*; Matsuda, Tatsuma; Haga, Yoshinori; Takeuchi, Tetsuya*; Sugiyama, Kiyohiro*; Settai, Rikio*; et al.
Physica B; Condensed Matter, 378-380, p.841 - 842, 2006/05
We have succeeded in growing single crystals of CeNiGe, which crystallizes in the orthorhombic crystal structure, by the flux method and studied the anisotropic physical properties by measuring the electrical resistivity, magnetic susceptibility and specific heat. The results of these measurements indicate that CeNiGe undergoes two antiferromagnetic transitions at =4.9 K and =4.3 K. The electrical resistivity and susceptibility measurements reveal strong anisotropic magnetic properties. From the specific heat measurement the electronic specific heat coefficient was found to be 90mJ/Kmol.
Nakashima, Miho*; Kohara, Hisanori*; Thamizhavel, A.*; Matsuda, Tatsuma; Haga, Yoshinori; Hedo, Masato*; Uwatoko, Yoshiya*; Settai, Rikio*; Onuki, Yoshichika
Physica B; Condensed Matter, 378-380, p.402 - 403, 2006/05
The Nel temperature of CeNiGe decreases with increasing pressure and becomes zero at a critical pressure 4 Gpa. The heavy fermion state was found to be formed around , in which pressure region superconductivity was found below 0.26 K.
Onuki, Yoshichika; Ikeda, Shugo; Yamagami, Hiroshi*; Galatanu, A.*; Haga, Yoshinori; Matsuda, Tatsuma; Yamamoto, Etsuji; Settai, Rikio*
Physica B; Condensed Matter, 378-380, p.972 - 973, 2006/05
no abstracts in English
Settai, Rikio*; Kubo, Tetsuo*; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika; Harima, Hisatomo*
Physica B; Condensed Matter, 378-380, p.417 - 418, 2006/05
We have studied a change of the Fermi surface in an antiferromagnet CeIn via the de Haas-van Alphen experiment for the magnetic field along  and  under pressure at about 2.7 GPa. We have observed a large main spherical Fermi surface named , which indicates that the electronic state of 4f electron in CeIn changes from localized to itinerant. The cyclotron effective mass of this main Fermi surface is extremely enhanced: 60 at 2.75 GPa for .
Aoki, Dai*; Yamagami, Hiroshi*; Homma, Yoshiya*; Shiokawa, Yoshinobu; Yamamoto, Etsuji; Nakamura, Akio; Haga, Yoshinori; Settai, Rikio*; Onuki, Yoshichika
Physica B; Condensed Matter, 378-380, p.978 - 980, 2006/05
no abstracts in English
Shimada, Kenya*; Namatame, Hirofumi*; Taniguchi, Masaki*; Higashiguchi, Mitsuharu*; Fujimori, Shinichi; Saito, Yuji; Fujimori, Atsushi; Kim, M. S.*; Hirata, Daisuke*; Takabatake, Toshiro*
Physica B; Condensed Matter, 378-380, p.791 - 792, 2006/05
The Ce 4f-derived states in CeRhX (X=Sn and In) were directly examined by means of high-resolution 3d-4f resonance photoemission spectroscopy. Compared with the Kondo metal CePtSn, which has a low Kondo temperature, CeRhX has a strong Ce 4f weight near the Fermi level () and has a weak Ce 4f peak, indicating a strong valence fluctuation. The Ce 4f spectral features indicate that the c-f hybridization strength in CeRhSn is weaker than that in CeRhIn.