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Journal Articles

Resonant X-ray scattering study of NpRhGa$$_5$$ and NpCoGa$$_5$$

Detlefs, B.*; Wilkins, S. B.*; Caciuffo, R.*; Paix$~a$o, J. A.*; Kaneko, Koji; Honda, Fuminori*; Metoki, Naoto; Bernhoeft, N.*; Rebizant, J.*; Lander, G. H.*

Physical Review B, 77(2), p.024425_1 - 024425_10, 2008/01

https://doi.org/10.1103/PhysRevB.77.024425
 Times Cited Count：17 Percentile：57.34(Materials Science, Multidisciplinary)

We report a resonant X-ray scattering study of the antiferromagnetic neptunium compounds NpCoGa$$_5$$ and NpRhGa$$_5$$. Large resonant signals of magnetic dipole character are observed below the N$'e$el temperatures. The signals at the Np edges confirm the behavior determined previously from neutron diffraction. On application of a magnetic field of 9 T along the [010] direction in NpRhGa$$_5$$, we observe a change in the population of different [110]-type domains. We also observe a magnetic dipole signal at the Ga $$K$$ edge, similarly to the reported UGa$$_3$$ case, that can be interpreted within a semilocalized model as an orbital polarization of the Ga 4$$p$$ states induced via strong hybridization with the Np 5$$f$$ valence band. Quantitative analysis of the signal shows that the Ga dipole on the two different Ga sites follows closely the Np magnetic moment reorientation in NpRhGa$$_5$$. The ratios of the signals on the two inequivalent Ga sites are not the same for the different compounds.

Journal Articles

Neutron scattering study on the field-induced $$O_{xy}$$-type antiferroquadrupolar ordering of the heavy-fermion superconductor PrOs$$_4$$Sb$$_{12}$$

Kaneko, Koji; Metoki, Naoto; Shiina, Ryosuke*; Matsuda, Tatsuma; Kogi, Masafumi*; Kuwahara, Keitaro*; Bernhoeft, N.*

Physical Review B, 75(9), p.094408_1 - 094408_7, 2007/03

https://doi.org/10.1103/PhysRevB.75.094408
 Times Cited Count：21 Percentile：63.99(Materials Science, Multidisciplinary)

Neutron scattering experiments have revealed a field-induced antiferroquadrupolar order parameter in the Pr-based heavy-fermion superconductor PrOs$$_4$$Sb$$_{12}$$. We observed the field-induced antiferromagnetic dipole moment with the propagation vector $$q$$ = (1 0 0) for the applied field direction both $$H parallel$$ [1 1 0] and [0 0 1]. For $$H parallel$$ [1 1 0] at 8 T, it should be noted that the induced antiferromagnetic moment of 0.16 $$mu_{rm B}$$/ Pr orients parallel to the field within our experimental accuracy. This observation is strong evidence that the $$O_{xy}$$ electric quadrupole to be the primary order parameter for $$H parallel$$ [1 1 0]. A mean-field calculation, based on $$Gamma_1$$ singlet and $${Gamma}_4^{(2)}$$ excited triplet with the $$O_{xy}$$ quadrupolar interaction, reproduces the induced moment direction and its field response. These facts indicate the predominance of $$O_{xy}$$-type antiferroquadrupolar interaction in PrOs$$_4$$Sb$$_{12}$$.

Journal Articles

Coexistence of antiferromagnetism and heavy-fermion superconductivity in CePt$$_{3}$$Si studied by neutron scattering

Kaneko, 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

Journal Articles

Magnetization dynamics in the normal and superconducting phases of UPd$$_2$$Al$$_3$$, 1; Surveys in reciprocal space using neutron inelastic scattering

Hiess, A.*; Bernhoeft, N.*; Metoki, Naoto; Lander, G.*; Roessli, B.*; Sato, Noriaki*; Aso, Naofumi*; Haga, Yoshinori; Koike, Yoshihiro*; Komatsubara, Takemi*; et al.

Journal of Physics; Condensed Matter, 18(27), p.R437 - R451, 2006/07

https://doi.org/10.1088/0953-8984/18/27/r01
 Times Cited Count：32 Percentile：32.94(Physics, Condensed Matter)

This topical review presents results from neutron inelastic scattering experiments on single crystals of UPd$$_2$$Al$$_3$$. We present a detailed and complete characterization of the wave vector- and energy-dependent magnetization dynamics in UPd$$_2$$Al$$_3$$ as measured by neutron inelastic scattering primarily in the form of extensive surveys in energy-momentum space under a wide range of experimental conditions, and put our observations in context with data that has been published previously by two independent groups. This study yields unique insight into the low-temperature ground state, which exhibits a microscopic coexistence of antiferromagnetism and superconductivity, makingUPd$$_2$$Al$$_3$$ one of the most accessible heavy-fermion superconductors that can be fully characterized by neutron spectroscopy.

Journal Articles

Field-induced antiferroquadrupolar order in the heavy fermion superconductor PrOs$$_4$$Sb$$_{12}$$

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

https://doi.org/10.1016/j.physb.2006.01.349
 Times Cited Count：1 Percentile：6.21(Physics, Condensed Matter)

Neutron diffraction experiments under magnetic fields were carried out on the heavy fermion superconductor PrOs$$_4$$Sb$$_{12}$$ in order to reveal the origin of the field-induced ordered phase (FIOP) for $$H$$$$Vert$$[1,1,0]. The application of magnetic field induces the weak superlattice peaks with the ordering vector $$q$$=(1,0,0) in FIOP, which is the same as for $$H{parallel}$$[0,0,1]. The observed superlattice reflections for $$H$$$$Vert$$[1,1,0] result from the antiferromagnetic component of $$J_x$$+$$J_y$$; 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 $$O_{xy}$$ as a primary order parameter. These facts clarify the dominant role of $$O_{xy}$$-type antiferroquadrupolar interaction in PrOs$$_4$$Sb$$_{12}$$.

Journal Articles

Induced orbital polarization of Ga ligand atoms in U$$T$$Ga$$_5$$ ($$T$$=Ni, Pd, and Pt)

Kuzushita, Kaori*; Ishii, Kenji; Wilkins, S. B.*; Janousova, B.*; Inami, Toshiya; Owada, Kenji; Tsubota, Masami; Murakami, Yoichi; Kaneko, Koji; Metoki, Naoto; et al.

Physical Review B, 73(10), p.104431_1 - 104431_5, 2006/03

https://doi.org/10.1103/PhysRevB.73.104431
 Times Cited Count：8 Percentile：37.60(Materials Science, Multidisciplinary)

We report a resonant X-ray scattering study of antiferromagnetic uranium compounds U$$T$$Ga$$_5$$ ($$T$$=Ni, Pd, and Pt) at the Ga $$K$$-edge. A large resonant signal is observed below the N$'e$el temperatures. The azimuth dependence in both $$pi$$-$$pi'$$ and $$pi$$-$$sigma'$$ polarization channels establishes that the resonant signal has the symmetry of the magnetic dipole. This resonance with the band electrons is interpreted within a semi-localized model as an orbital polarization of the Ga $$4p$$ states induced through strong hybridization with U $$5f$$ valence level. These results demonstrate that resonant magnetic X-ray scattering at the anions, taken in combination with symmetry arguments, can be used to determine the configuration of the U $$5f$$ moments and provide information about the hybridization.

Journal Articles

Magnetic structure and metamagnetism in single crystals of NpCoGa$$_{5}$$

Metoki, Naoto; Kaneko, Koji; Colineau, E.*; Javorsk$'y$, P.*; Aoki, Dai*; Homma, Yoshiya*; Boulet, P.*; Wastin, F.*; Shiokawa, Yoshinobu; Bernhoeft, N.*; et al.

Physical Review B, 72(1), p.014460_1 - 014460_8, 2005/07

https://doi.org/10.1103/PhysRevB.72.014460
 Times Cited Count：50 Percentile：83.18(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Magnetic structure and crystal field excitation in heavy fermion superconductor CePt$$_{3}$$Si

Metoki, Naoto; Kaneko, Koji; Matsuda, Tatsuma; Galatanu, A.; Takeuchi, Tetsuya*; Hashimoto, Shin*; Ueda, Taiki*; Settai, Rikio*; Onuki, Yoshichika*; Bernhoeft, N.*

Physica B; Condensed Matter, 359-361, p.383 - 385, 2005/06

https://doi.org/10.1016/j.physb.2005.01.070
 Times Cited Count：1 Percentile：5.92(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Magnetic structure of NpTGa$$_{5}$$(T: Fe, Co, Ni)

Honda, Fuminori; Metoki, Naoto; Kaneko, Koji; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Shiokawa, Yoshinobu; Onuki, Yoshichika; Colineau, E.*; Bernhoeft, N.*; et al.

Physica B; Condensed Matter, 359-361, p.1147 - 1149, 2005/06

https://doi.org/10.1016/j.physb.2005.01.304
 Times Cited Count：26 Percentile：68.54(Physics, Condensed Matter)

We have succeeded in growing single crystalline samples of NpTGa$$_{5}$$ (T: Fe, Co, Ni). Magnetic structures of these compounds have been studied by neutron diffraction experiment. We summarize the results of the unusual variety of magnetic structure occurred in NpTGa$$_{5}$$ and discuss in terms of electronic structural point of view.

Journal Articles

Neutron scattering study on the field-induced antiferro-quadrupolar ordering in the heavy fermion superconductor PrOs$$_{4}$$Sb$$_{12}$$

Metoki, Naoto; Kaneko, Koji; Araki, Shingo; Kogi, Masafumi*; Iwasa, Kazuaki*; Kuwahara, Keitaro*; Bernhoeft, N.*; Mignot, J.-M.*; Gukasov, A.*; Sato, Hideyuki*; et al.

Journal of Magnetism and Magnetic Materials, 272-276(Suppl.), p.e91 - e92, 2004/05

https://doi.org/10.1016/j.jmmm.2003.11.315
 Times Cited Count：1 Percentile：6.82(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Magnetic structure and the crystal field excitation in heavy-fermion antiferromagnetic superconductor CePt$$_{3}$$Si

Metoki, Naoto; Kaneko, Koji; Matsuda, Tatsuma; Galatanu, A.; Takeuchi, Tetsuya*; Hashimoto, Shin*; Ueda, Taiki*; Settai, Rikio*; Onuki, Yoshichika; Bernhoeft, N.*

Journal of Physics; Condensed Matter, 16(15), p.L207 - L212, 2004/04

https://doi.org/10.1088/0953-8984/16/15/L01
 Times Cited Count：92 Percentile：93.35(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Large orbital magnetic moment and its quenching in the itinerant uranium intermetallic compounds U${it T}$Ga$$_5$$ (${it T}$=Ni, Pd, Pt)

Kaneko, Koji; Metoki, Naoto; Bernhoeft, N.*; Lander, G. H.; Ishii, Yoshinobu; Ikeda, Shugo; Tokiwa, Yoshifumi; Haga, Yoshinori; Onuki, Yoshichika

Physical Review B, 68(21), p.214419_1 - 214419_9, 2003/12

https://doi.org/10.1103/PhysRevB.68.214419
 Times Cited Count：59 Percentile：88.45(Materials Science, Multidisciplinary)

The crystal structure, lattice strain due to the antiferromagnetic ordering and magnetic form factor in the itinerant 5$$f$$ compounds UTGa$$_5$$ (T: Ni, Pd, Pt) have been studied by neutron scattering. High-resolution powder diffraction revealed that the tetragonality of the U-Ga layers increases with the ionic radius of the transition metal element T. The observed antiferromagnetic reflections can be well explained with the N$'e$el-type structure for UNiGa$$_5$$, whereas UPtGa$$_5$$ has the antiferromagnetic stacking of the ferromagnetically ordered uranium moments in the $$c$$-plane. The orbital contributions in the magnetic form factor are reduced from the free ion value, especially for UNiGa$$_5$$. This suppression shows a strong correlation with the bulk magnetic susceptibility. The tetragonality of the U-Ga layers is a sensitive measure of the nearest neighbour interaction, the lattice anomaly, and the orbital contribution and suggests that orbital degrees of freedom may play an important role for the magnetic properties in these itinerant 5$$f$$ antiferromagnets.

Journal Articles

Evidence for magnetic-field-induced quadrupolar ordering in the heavy-fermion superconductor PrOs$$_{4}$$Sb$$_{12}$$

Kogi, Masafumi*; Iwasa, Kazuaki*; Nakajima, Motoki*; Metoki, Naoto; Araki, Shingo; Bernhoeft, N.*; Mignot, J.-M.*; Gukasov, A.*; Sato, Hideyuki*; Aoki, Yuji*; et al.

Journal of the Physical Society of Japan, 72(5), p.1002 - 1005, 2003/05

https://doi.org/10.1143/JPSJ.72.1002
 Times Cited Count：199 Percentile：97.15(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Neutron diffractioin study of 5$${it f}$$ itinerant antiferromagnet UPtGa$$_{5}$$ and UNiGa$$_{5}$$

Kaneko, Koji; Metoki, Naoto; Lander, G. H.*; Bernhoeft, N.*; Tokiwa, Yoshifumi; Haga, Yoshinori; Onuki, Yoshichika; Ishii, Yoshinobu

Physica B; Condensed Matter, 329-333(1-4), p.510 - 511, 2003/05

https://doi.org/10.1016/S0921-4526(02)02186-5
 Times Cited Count：3 Percentile：20.87(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Magnetic excitations in an itinerant 5${it f}$ antiferromagnet UPt$$_{2}$$Si$$_{2}$$

Metoki, 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

http://www.actaphys.uj.edu.pl/_cur/store/vol34/pdf/v34p0979.pdf

no abstracts in English

Oral presentation

Neutron scattering study on field-induced ordered phase and rattling in PrOs$$_4$$Sb$$_{12}$$

Kaneko, Koji; Metoki, Naoto; Kimura, Hiroyuki*; Noda, Yukio*; Matsuda, Tatsuma; Shiina, Ryosuke*; Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Bernhoeft, N.*

no journal, , 

no abstracts in English

16 (Records 1-16 displayed on this page)
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