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Journal Articles

The $$f$$-electron state of the heavy fermion superconductor NpPd$$_5$$Al$$_2$$ and the isostructural family

Metoki, Naoto; Aczel, A. A.*; Aoki, Dai*; Chi, S.*; Fernandez-Baca, J. A.*; Griveau, J.-C.*; Hagihala, Masato*; Hong, T.*; Haga, Yoshinori; Ikeuchi, Kazuhiko*; et al.

JPS Conference Proceedings (Internet), 30, p.011123_1 - 011123_6, 2020/03

Rare earths (4$$f$$) and actinides (5$$f$$) provide variety of interesting states realized with competing interactions between the increasing number of $$f$$ electrons. Since crystal field splitting of many-body $$f$$ electron system is smaller than the bandwidth, (1) high resolution experiments are needed, (2) essentially no clear spectrum with well defined peaks is expected in itinerant Ce and U compounds, and (3) Np and Pu is strictly regulated. Therefore, systematic research on magnetic excitations by neutron scattering experiments of localized compounds and rare earth iso-structural reference is useful. We describe the $$f$$ electron states of heavy electron compounds NpPd$$_5$$Al$$_2$$ and actinide and rare earth based iso-structural family.

Journal Articles

Study on use of superconducting magnet and first inelastic neutron scattering experiment under magnetic field at 4SEASONS spectrometer

Kajimoto, Ryoichi; Ishikado, Motoyuki*; Kira, Hiroshi*; Kaneko, Koji; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Murai, Naoki; et al.

Physica B; Condensed Matter, 556, p.26 - 30, 2019/03

 Times Cited Count:2 Percentile:51.08(Physics, Condensed Matter)

Journal Articles

Performances of oscillating radial collimator for the Fermi chopper spectrometer 4SEASONS at J-PARC

Nakamura, Mitsutaka; Kambara, Wataru*; Iida, Kazuki*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Ishikado, Motoyuki*; Aoyama, Kazuhiro*

Physica B; Condensed Matter, 551, p.480 - 483, 2018/12

 Times Cited Count:1 Percentile:86.03(Physics, Condensed Matter)

Recently there has been an increasing need for inelastic neutron scattering experiments under some special environments such as magnetic fields, pressure and high temperatures. In order to obtain high quality data, the unnecessary scattering caused by sample environmental apparatus should be suppressed as much as possible. We have developed an oscillating radial collimator with a view to satisfying users' needs, which is specialized for the Fermi chopper spectrometer 4SEASONS at J-PARC.4SEASONS provides relatively high incident energies, and thus we chose hydrogen free metal sheets as the collimator blades. The control system of this oscillating radial collimator enables us to flexibly tune the oscillating pattern, such as the oscillating speed and oscillating angle. In this presentation, we report the performances and remaining issues of the newly developed oscillating radial collimator for 4SEASONS.

Journal Articles

Phonon dynamics of NaI investigated by G($$r,E$$) analysis

Nakamura, Mitsutaka; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Kawakita, Yukinobu

Physica B; Condensed Matter, 551, p.351 - 354, 2018/12

 Times Cited Count:2 Percentile:73.1(Physics, Condensed Matter)

The dynamic structure function in real space G($$r,E$$) is deduced from the dynamical structure factor S($$Q,E$$) which can be obtained from inelastic neutron scattering measurement. In this study, we applied the G($$r,E$$) analysis to NaI which is a typical alkali halide crystal. The optic and acoustic phonons of NaI are widely separated in energy because the difference in mass between the constituent atoms is large. These characteristic properties certainly help us to evaluate the G($$r,E$$) features associated with the phonon modes. We measured the S($$Q,E$$) for NaI powder using the Fermi chopper spectrometer 4SEASONS at J-PARC, and converted S($$Q,E$$) into G($$r,E$$) by newly developed software which utilizes the maximum entropy method. Our analysis clearly demonstrated the G($$r,E$$) of TO mode oscillates out of phase with that of LA mode, which is physically reasonable. Further analyses will be given in the presentation.

Journal Articles

Neutron inelastic scattering study of the $$f$$-electron states in NdPd$$_5$$Al$$_2$$

Metoki, Naoto; Yamauchi, Hiroki; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro

Journal of the Physical Society of Japan, 87(8), p.084708_1 - 084708_7, 2018/08

 Times Cited Count:5 Percentile:32.14(Physics, Multidisciplinary)

Inelastic neutron scattering experiments were carried out in order to study the $$f$$-electron states of NdPd$$_5$$Al$$_2$$The CEF levels at 0K, 35.4K, 88.3K, 101.5K, and 198.8K were clarified from the excitation spectra. The $$Gamma_6$$ ground state contains the orbital with $$J_z=pm9/2$$ as a main component due to a large negative B$$_{20}=-1.4$$K, which is the origin of the strong uniaxial anisotropy. The estimated magnetic moment, the calculated susceptibility, magnetization curve, and specific heat are in good agreement with the experimental data. The existence of a common charge distribution with CePd$$_5$$Al$$_2$$ and PrPd$$_5$$Al$$_2$$. Indicates that a localized character is important even in actinide-based iso-structural compounds as actually observed in UPd$$_5$$Al$$_2$$ and also NpPd$$_5$$Al$$_2$$, in which the valence crossover plays important role for the heavy fermion superconductivity.

Journal Articles

Status report of the chopper spectrometer 4SEASONS

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Murai, Naoki; Kira, Hiroshi*; Nakatani, Takeshi; et al.

Journal of Physics; Conference Series, 1021(1), p.012030_1 - 012030_6, 2018/06

 Times Cited Count:2 Percentile:9.36

Journal Articles

Magnetic excitations in the orbital disordered phase of MnV$$_2$$O$$_4$$

Matsuura, Keisuke*; Sagayama, Hajime*; Uehara, Amane*; Nii, Yoichi*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Ji, S.*; Abe, Nobuyuki*; Arima, Takahisa*

Physica B; Condensed Matter, 536, p.372 - 376, 2018/05

 Times Cited Count:1 Percentile:86.03(Physics, Condensed Matter)

JAEA Reports

Proceedings of the MLF User Group Meeting on Direct Geometry Spectrometers (DIRECTION 2017); October 16-17, 2017, Ibaraki Quantum Beam Research Center (Tokai, Ibaraki, Japan)

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Kamazawa, Kazuya*; Nakamura, Mitsutaka; Kawamura, Seiko; Ito, Shinichi*; Nakajima, Kenji

JAEA-Review 2017-031, 107 Pages, 2018/02

JAEA-Review-2017-031.pdf:17.43MB

The joint user meeting for four direct-geometry neutron spectrometers in the Materials and Life Science Experimental Facility (MLF) at J-PARC, "DIRECTION 2017", was held at the Ibaraki Quantum Beam Research Center building on October 16th - 17th, 2017. This meeting was purposed to encourage the user activities on the four instruments 4SEASONS (BL01), HRC (BL12), AMATERAS (BL14), and POLANO (BL23), and was jointly organized by J-PARC MLF, KEK-IMSS, and CROSS. In this meeting, recent research activities using these instruments were reported in addition to the current status of the instruments, the sample environments, and software. This report compiles the presentation materials and their abstracts.

Journal Articles

Observation of magnetoelastic effects in a quasi-one-dimensional spiral magnet

Wang, C.*; Daiwei, Y.*; Liu, X.*; Chen, R.*; Du, X.*; Hu, B.*; Wang, L.*; Iida, Kazuki*; Kamazawa, Kazuya*; Wakimoto, Shuichi; et al.

Physical Review B, 96(8), p.085111_1 - 085111_5, 2017/08

AA2017-0274.pdf:1.02MB

 Times Cited Count:3 Percentile:69.03(Materials Science, Multidisciplinary)

Journal Articles

Spin wave dispersion just above the magnetic order-order transition in the metallic antiferromagnet Mn$$_{3}$$Pt

Ibuka, Soshi*; Yokoo, Tetsuya*; Ito, Shinichi*; Kamazawa, Kazuya*; Nakamura, Mitsutaka; Imai, Motoharu*

Journal of Physics; Conference Series, 868(1), p.012017_1 - 012017_6, 2017/07

Spin wave dispersion of the metallic antiferromagnet Mn$$_{3}$$Pt was investigated just above the order-order transition temperature by using the inelastic neutron scattering technique. The spin wave dispersion at $$T$$ = 400 K along [100], [110] and [111] directions was isotropic within the measurement accuracy. These results show that large reduction of the stiffness constant with increasing temperature, and indicate the itinerancy of the magnetic moments.

Journal Articles

Spin-orbital correlated dynamics in the spinel-type vanadium oxide MnV$$_{2}$$O$$_{4}$$

Matsuura, Keisuke*; Sagayama, Hajime*; Uehara, Amane*; Nii, Yoichi*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Ji, S.*; Abe, Nobuyuki*; Arima, Takahisa*

Physical Review Letters, 119(1), p.017201_1 - 017201_6, 2017/07

 Times Cited Count:6 Percentile:35.42(Physics, Multidisciplinary)

Journal Articles

Time-of-flight elastic and inelastic neutron scattering studies on the localized 4d electron layered perovskite La$$_5$$Mo$$_4$$O$$_{16}$$

Iida, Kazuki*; Kajimoto, Ryoichi; Mizuno, Yusuke*; Kamazawa, Kazuya*; Inamura, Yasuhiro; Hoshikawa, Akinori*; Yoshida, Yukihiko*; Matsukawa, Takeshi*; Ishigaki, Toru*; Kawamura, Yukihiko*; et al.

Journal of the Physical Society of Japan, 86(6), p.064803_1 - 064803_6, 2017/06

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

Journal Articles

Interaction of spin-orbital-lattice degrees of freedom; Vibronic state of the corner-sharing-tetrahedral frustrated spin system HoBaFe$$_{4}$$O$$_{7}$$ by dynamical Jahn-Teller effect

Kamazawa, Kazuya*; Ishikado, Motoyuki*; Kawamura, Seiko; Kawakita, Yukinobu; Kakurai, Kazuhisa*; Nakajima, Kenji; Sato, Masashi*

Physical Review B, 95(10), p.104413_1 - 104413_7, 2017/03

 Times Cited Count:2 Percentile:78.36(Materials Science, Multidisciplinary)

Journal Articles

MAGIC chopper; Basic concept and experimental evaluation

Nakamura, Mitsutaka; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Kambara, Wataru; Krist, T.*; Shinohara, Takenao; Arai, Masatoshi; Iida, Kazuki*; Kamazawa, Kazuya*; Inamura, Yasuhiro; et al.

JAEA-Conf 2015-002, p.339 - 348, 2016/02

We have developed a new Fermi chopper referred to as Magic chopper to realize the full optimization of the experimental condition for Multi-Ei method in a chopper spectrometer. In this study, the theoretical aspects of MAGIC chopper concept will be initially presented, and the performances of MAGIC chopper will be evaluated by both Monte Carlo simulation and neutron transmission experiment.

Journal Articles

Recent progress in the chopper spectrometer 4SEASONS at J-PARC

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Nakajima, Kenji; Kawamura, Seiko; Nakatani, Takeshi; et al.

JAEA-Conf 2015-002, p.319 - 329, 2016/02

Journal Articles

Background caused by continuously emitted high-energy neutrons at the chopper spectrometer 4SEASONS

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Nakajima, Kenji; Harada, Masahide; Arai, Masatoshi

JPS Conference Proceedings (Internet), 8, p.036001_1 - 036001_6, 2015/09

Journal Articles

Oscillating radial collimators for the chopper spectrometers at MLF in J-PARC

Nakamura, Mitsutaka; Kawakita, Yukinobu; Kambara, Wataru; Aoyama, Kazuhiro; Kajimoto, Ryoichi; Nakajima, Kenji; Kawamura, Seiko; Ikeuchi, Kazuhiko*; Kikuchi, Tatsuya; Inamura, Yasuhiro; et al.

JPS Conference Proceedings (Internet), 8, p.036011_1 - 036011_6, 2015/09

The needs for inelastic neutron scattering experiments under the special sample environment such as strong magnetic field and high temperature are recently increasing. However, the unwanted scatterings originating from these devices affect the detection of weak inelastic signals. In order to overcome this problem we have developed an oscillating radial collimator specialized for the chopper spectrometer at Materials and Life Science Experimental Facility (MLF) in J-PARC. In this study, we will report the performances of newly-developed oscillating radial collimators both for 4SEASONS and AMATERAS.

Journal Articles

Frustrated minority spins in GeNi$$_2$$O$$_4$$

Matsuda, Masaaki; Chung, J.-H.*; Park, S.*; Sato, Taku*; Matsuno, Kenichiro*; Katori, Hiroko*; Takagi, Hidenori*; Kakurai, Kazuhisa; Kamazawa, Kazuya*; Tsunoda, Yorihiko*; et al.

Europhysics Letters, 82(3), p.37006_1 - 37006_5, 2008/05

 Times Cited Count:13 Percentile:35.9(Physics, Multidisciplinary)

Recently, two consecutive phase transitions were observed, upon cooling, in an antiferromagnetic spinel GeNi$$_2$$O$$_4$$ at $$T_{N1}=12.1$$ K and $$T_{N2}=11.4$$ K, respectively. Using unpolarized and polarized elastic neutron scattering we show that the two transitions are due to the existence of frustrated minority spins in this compound. Upon cooling, at $$T_{N1}$$ the spins on the $$<$$111$$>$$ kagom$'e$ planes order ferromagnetically in the plane and antiferromagnetically between the planes (phase I), leaving the spins on the $$<$$111$$>$$ triangular planes that separate the kagom$'e$ planes frustrated and disordered. At the lower $$T_{N2}$$, the triangular spins also order in the $$<$$111$$>$$ plane (phase II). We also present a scenario involving exchange interactions that qualitatively explains the origin of the two purely magnetic phase transitions.

Journal Articles

Magnetic field effects on the diffuse scattering of a spin-frustrated spinel ferrite ZnFe$$_{2}$$O$$_{4}$$ single crystal

Kamazawa, Kazuya*; Katano, Susumu; Tsunoda, Yorihiko*

Physica B; Condensed Matter, B345(1-4), p.96 - 98, 2004/03

 Times Cited Count:3 Percentile:78.66(Physics, Condensed Matter)

no abstracts in English

Oral presentation

Construction status of the Si crystal analyzer backscattering type high energy resolution spectrometer DNA, 5

Shibata, Kaoru*; Takahashi, Nobuaki; Kawakita, Yukinobu; Kamazawa, Kazuya*; Yamada, Takeshi*; Ueno, Hiroki; Shimakura, Hironori; Nakajima, Kenji; Kambara, Wataru; Inamura, Yasuhiro; et al.

no journal, , 

no abstracts in English

57 (Records 1-20 displayed on this page)