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CoSiYamauchi, Hiroki; Sari, D. P.*; Yasui, Yukio*; Sakakura, Terutoshi*; Kimura, Hiroyuki*; Nakao, Akiko*; Ohara, Takashi; Honda, Takashi*; Kodama, Katsuaki; Igawa, Naoki; et al.
Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02
Hashimoto, Shunsuke*; Nakajima, Kenji; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Shibata, Kaoru; Yamada, Takeshi*
Journal of Molecular Liquids, 342, p.117580_1 - 117580_8, 2021/11
Times Cited Count：3 Percentile：25.84(Chemistry, Physical)Quasi-elastic neutron scattering (QENS) and pulsed-field-gradient nuclear magnetic resonance (PFGNMR) analyses of a nanofluid composed of silicon dioxide (SiO
) nanoparticles and a base fluid of ethylene glycol aqueous solution were performed. The aim was to elucidate the mechanism increase in the thermal conductivity of the nanofluid above its theoretical value. The obtained experimental results indicate that SiO particles may decrease the self-diffusion coefficient of the liquid molecules in the ethylene glycol aqueous solution because of their highly restricted motion around these nanoparticles. At a constant temperature, the thermal conductivity increases as the self-diffusion coefficient of the liquid molecules decreases in the SiO nanofluids.
Kuroda, Kenta*; Arai, Yosuke*; Rezaei, N.*; Kunisada, So*; Sakuragi, Shunsuke*; Alaei, M.*; Kinoshita, Yuto*; Bareille, C.*; Noguchi, Ryo*; Nakayama, Mitsuhiro*; et al.
Nature Communications (Internet), 11, p.2888_1 - 2888_9, 2020/06
Times Cited Count：21 Percentile：74.83(Multidisciplinary Sciences)Kawamura, Seiko; Takahashi, Ryuta*; Ishikado, Motoyuki*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ouchi, Keiichi*; Kira, Hiroshi*; Kambara, Wataru*; Aoyama, Kazuhiro*; Sakaguchi, Yoshifumi*; et al.
Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05
The Cryogenics and Magnets group in the Sample Environment team is responsible for operation of cryostats and magnets for user's experiments at the MLF in J-PARC. We have introduced a top-loading 
He cryostat, a bottom-loading 
He cryostat, a dilution refrigerator insert and a superconducting magnet. The frequency of use of them dramatically becomes higher in these two years, as the beam power and the number of proposal increase. To respond such situation, we have made efforts to enhance performance of these equipment as follows. The He cryostat originally involves an operation software for automatic initial cooling down to the base temperature and automatic re-charge of He. Recently we made an additional program for automatic temperature control with only the sorb heater. Last year, a new outer vacuum chamber of the magnet with an oscillating radial collimator (ORC) was fabricated. The data quality was drastically improved by introducing this ORC so that the magnet can be used even for the inelastic neutron scattering experiments.
; Soft X-ray absorption, magnetic circular dichroism, and angle-resolved photoemission spectroscopiesSaito, Yuji; Fujiwara, Hidenori*; Yamaguchi, Takashi*; Nakatani, Yasuhiro*; Mori, Takeo*; Fuchimoto, Hiroto*; Kiss, Takayuki*; Yasui, Akira*; Miyawaki, Jun*; Imada, Shin*; et al.
Journal of the Physical Society of Japan, 85(11), p.114713_1 - 114713_7, 2016/11
Times Cited Count：15 Percentile：67.86(Physics, Multidisciplinary)We report on the electronic structures of ferromagnetic CeAgSb using soft X-ray absorption (XAS), magnetic circular dichroism (XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce 
XAS spectra show very small satellite structures, reflecting a strongly localized character of the Ce 4
electrons. The linear dichroism effects in the Ce XAS spectra demonstrate the ground-state Ce 4 symmetry of 
, the spatial distribution of which is directed along the 
-axis. Nevertheless, ARPES spectra at the Ce 3
-4
resonance show the momentum dependence of the intensity ratio between Ce 4
and 4
peaks in a part of the Brillouin zone, suggesting the non negligible momentum-dependent hybridization effect between the Ce 4 and the conduction electrons. This is associated with the moderate mass enhancement in CeAgSb.
Oba, Yojiro*; Morooka, Satoshi; Oishi, Kazuki*; Sato, Nobuhiro*; Inoue, Rintaro*; Adachi, Nozomu*; Suzuki, Junichi*; Tsuchiyama, Toshihiro*; Gilbert, E. P.*; Sugiyama, Masaaki*
Journal of Applied Crystallography, 49(5), p.1659 - 1664, 2016/10
Times Cited Count：13 Percentile：66.38(Chemistry, Multidisciplinary) 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.
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.
Sakamoto, Shinichi; Meigo, Shinichiro; Fujimori, Hiroshi*; Harada, Masahide; Konno, Chikara; Kasugai, Yoshimi; Kai, Tetsuya; Miyake, Yasuhiro*; Ikeda, Yujiro
Nuclear Instruments and Methods in Physics Research A, 562(2), p.638 - 641, 2006/06
Times Cited Count：8 Percentile：50.27(Instruments & Instrumentation)Materials and Life Science Facility of Japan Proton Accelerator Research Complex (J-PARC) is an experimental facility where neutron and muon beams are provided as powerful probes. They are generated with high-intensity proton beam supplied through a 3-GeV proton beam transport (3NBT) line. Its beam optics and components were designed to transport the proton beam of large emittance with extremely low loss rate. The 3NBT accommodates an intermediate target that causes large beam loss. The scheme of the cascade target system was carefully devised to overcome difficulties due to high radiation.
Kubo, Katsunori; Hotta, Takashi
Journal of the Physical Society of Japan, 75(1), p.013702_1 - 013702_4, 2006/01
Times Cited Count：11 Percentile：56.28(Physics, Multidisciplinary)Effects of orbital degeneracy on magnetic susceptibility in paramagnetic phases are investigated within a mean-field theory. Under certain crystalline electric fields, the magnetic moment consists of two independent moments, e.g., spin and orbital moments. In such a case, the magnetic susceptibility is given by the sum of two different Curie-Weiss relations, leading to the deviation from the Curie-Weiss law. Such behavior may be observed in - and -electron systems with 
and 
ground states, respectively. As a potential application of our theory, we attempt to explain the difference in the temperature dependence of magnetic susceptibilities of UO and NpO. Then, we find that the difference in the temperature dependence can be naturally explained by considering the effects of the octupole moments in NpO.
-dependence of spin exchange interactions in MnO
( = Rare-Earth Ions)Kajimoto, Ryoichi; Mochizuki, Hidenori*; Yoshizawa, Hideki*; Shintani, Hiroshi*; Kimura, Tsuyoshi*; Tokura, Yoshinori*
Journal of the Physical Society of Japan, 74(9), p.2430 - 2433, 2005/09
Times Cited Count：37 Percentile：79.55(Physics, Multidisciplinary)Magnon excitations have been investigated for PrMnO showing the 
-type antiferromagnetic ordering and TbMnO forming a long-period spin ordering by inelastic neutron scattering. Combined with a result of LaMnO [K.~Hirota 
], the systematic data revealed that the ferromagnetic exchange interaction between nearest-neighbor (NN) Mn sites within the 
plane drastically decreases in MnO as the ionic radius of is reduced. In addition, finite next-nearest-neighbor (NNN) coupling is evident in TbMnO. In contrast, the exchange interaction along the 
axis shows much weaker dependence consistent with the Mn-O-Mn bond angle. These observations confirm a scenario that explains the evolution of spin structures in MnO in terms of the competition between the NN and NNN interactions [T.Kimura ].
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：6.21(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：39 Percentile：79.98(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.
SiMatsuda, Tatsuma; Haga, Yoshinori; Ikeda, Shugo; Galatanu, A.; Onuki, Yoshichika
Physica B; Condensed Matter, 359-361, p.1069 - 1071, 2005/04
Times Cited Count：3 Percentile：16.98(Physics, Condensed Matter)We have succeeded in growing a high-quality single crystal of UCuSi with the tetragonal structure by the Sn-flux method and measured the magnetic susceptibility and magnetization. UCuSi is confirmed to order antiferromagnetically below 
= 106 K, and follows a successive ferromagnetic ordering at 
= 100 K. The magnetic properties are highly anisotropic, reflecting the crystal structure. An easy-axis of magnetization is found to be the [001] direction (-axis), while the [100] direction (
-axis) corresponds to the hard-axis in magnetization. The saturation moment is determined as 1.8
/U.
Mg
FIto, Shinichi*; Kajimoto, Ryoichi; Adams, M. A.*
Journal of the Physical Society of Japan, 74(1), p.279 - 282, 2005/01
Times Cited Count：3 Percentile：26.63(Physics, Multidisciplinary)Magnetic fractons in the near-percolating three-dimensional (3D) Heisenberg antiferromagnet, RbMn
MgF, have been studied using inelastic neutron scattering with high energy resolution (
eV) and at low temperature (
K). It is demonstrated that the fractons follow the dispersion relation of 
(q being the wave number). The observed exponent, 
, is in good agreement with the fractal dimension of the 3D system (
), as predicted by theory.
hole-assisted electronic processes in the Pr
Sr
MnO (x=0.0, 0.3) systemIbrahim, K.*; Qian, H. J.*; Wu, X.*; Abbas, M. I.*; Wang, J. O.*; Hong, C. H.*; Su, R.*; Zhong, J.*; Dong, Y. H.*; Wu, Z. Y.*; et al.
Physical Review B, 70(22), p.224433_1 - 224433_9, 2004/12
Times Cited Count：30 Percentile：75.04(Materials Science, Multidisciplinary)no abstracts in English
Tomiyasu, Keisuke*; Inami, Toshiya; Ikeda, Naoshi*
Physical Review B, 70(11), p.184411_1 - 184411_6, 2004/11
Times Cited Count：43 Percentile：83.13(Materials Science, Multidisciplinary)Below 
= 289 K, the antiferromagnet CoO exhibits magnetic long-range order described by a propagation vector along the trigonal axis, whereas the lattice is distorted monoclinicly along both the tetragonal and the trigonal axes. In order to elucidate this inconsistency, we performed neutron and synchrotron X-ray diffraction experiments on single crystals of CoO, and found a new series of magnetic reflections represented by a propagation vector along the tetragonal axis below N. These results suggest an altered magnetic structure of CoO, which includes both the trigonal and the tetragonal propagation vectors, has a monoclinic symmetry and which is in accordance with the distorted lattice symmetry.
Hoshiya, Taiji*; Takaya, Shigeru*; Ueno, Fumiyoshi; Nemoto, Yoshiyuki; Nagae, Yuji*; Miwa, Yukio; Abe, Yasuhiro*; Omi, Masao; Tsukada, Takashi; Aoto, Kazumi*
Transactions of the Materials Research Society of Japan, 29(4), p.1687 - 1690, 2004/06
JAERI and JNC have begun the cooperative research of evaluation techniques of structural material degradation in FBR and LWR, which based on magnetic and corrosion properties along grain boundaries. Magnetic method has been proposed as the one of the non-destructive detection techniques on the early stage of creep-damage before crack initiation for aged structural materials of FBRs. The effects of applied stress on natural magnetization were investigated on paramagnetic stainless steels having creep-damages. On the other hand, corrosion properties and magneto-optical characteristics of ion-irradiated stainless steels in the vicinity of grain boundaries were estimated by AFM and Kerr effect microscope, respectively. These degradations were induced by changes in characteristics in the vicinity of grain boundaries. It is found that the initial level of progressing process of damage can detect changes in magnetic and corrosion properties along grain boundaries of aged and degraded nuclear plants structural materials.
Ikeda, Shugo; Matsuda, Tatsuma; Galatanu, A.; Yamamoto, Etsuji; Haga, Yoshinori; Onuki, Yoshichika
Journal of Magnetism and Magnetic Materials, 272-276(1), p.62 - 63, 2004/05
Times Cited Count：6 Percentile：34.09(Materials Science, Multidisciplinary)We have succeeded in growing a single crystal of an antiferromagnet UNiSb by the self-flux method. The magnetic susceptibility is found to be highly anisotropic, reflecting the quasi-two dimensional tetragonal crystal structure. The magnetic easy-axis is determined as the [001] direction, consistent with the result of the neutron scattering experiments.
Mikhailovskii, A. B.*; Kovalishen, E. A.*; Shirokov, M. S.*; Konovalov, S. V.; Tsypin, V. S.*; Kamenets, F. F.*; Ozeki, Takahisa; Takizuka, Tomonori
Physics of Plasmas, 11(2), p.666 - 676, 2004/02
Times Cited Count：6 Percentile：20(Physics, Fluids & Plasmas)Analytical treatment of magnetic islands with high poloidal mode numbers and widths smaller than ion Larmor radius (microislands) is presented. The profile functions and rotation frequencies of microislands are investigated with the two-fluid magnetohydrodynamics. The microislands are described in terms of two profile functions, one of which characterizes the electric field and perturbed plasma density, and second the perturbed electron temperature. The problem of rotation frequencies of microislands is discussed.
