Experimental evidence for the significance of optical phonons in thermal transport of tin monosulfide

Wu, P.*; Murai, Naoki; Li, T.*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Kofu, Maiko; Nakajima, Kenji; Xia, K.*; Peng, K.*; Zhang, Y.*; et al.

New Journal of Physics (Internet), 25(1), p.013032_1 - 013032_11, 2023/01

https://doi.org/10.1088/1367-2630/acb3ed

Localized 5 states in UPdAl and valence crossover in the Vicinity of Heavy-Fermion superconductivity

Metoki, Naoto; Haga, Yoshinori; Yamamoto, Etsuji; Matsuda, Masaaki*

Journal of the Physical Society of Japan, 87(11), p.114712_1 - 114712_9, 2018/11

https://doi.org/10.7566/JPSJ.87.114712

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.

Neutron inelastic scattering study of the -electron states in NdPdAl

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

https://doi.org/10.7566/JPSJ.87.084708

Inelastic neutron scattering experiments were carried out in order to study the -electron states of NdPdAlThe CEF levels at 0K, 35.4K, 88.3K, 101.5K, and 198.8K were clarified from the excitation spectra. The ground state contains the orbital with as a main component due to a large negative BK, 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 CePdAl and PrPdAl. Indicates that a localized character is important even in actinide-based iso-structural compounds as actually observed in UPdAl and also NpPdAl, in which the valence crossover plays important role for the heavy fermion superconductivity.

Polar rotor scattering as atomic-level origin of low mobility and thermal conductivity of perovskite CHNHPbI

Li, B.; Kawakita, Yukinobu; Liu, Y.*; Wang, M.*; Matsuura, Masato*; Shibata, Kaoru; Kawamura, Seiko; Yamada, Takeshi*; Lin, S.*; Nakajima, Kenji; et al.

Nature Communications (Internet), 8, p.16086_1 - 16086_9, 2017/06

https://doi.org/10.1038/ncomms16086

Inelastic neutron scattering study on low-energy excitations of the heavy-fermion superconductor PrOsSb

Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Kaneko, Koji; Metoki, Naoto; Raymond, S.*; Masson, M.-A.*; Flouquet, J.*; Sugawara, Hitoshi*; Aoki, Yuji*; et al.

Physica B; Condensed Matter, 385-386(Part 1), p.82 - 84, 2006/11

https://doi.org/10.1016/j.physb.2006.05.109

We report inelastic neutron scattering experiments performed to investigate the low energy magnetic excitations on single crystals of the heavy-fermion superconductor PrOsSb. The observed excitation clearly softens at a wave vector Q=(1,0,0), which is the same as the modulation vector of the field-induced antiferro-quadrupolar ordering, and its intensity at Q=(1,0,0) is smaller than that around the zone center. This result directly evidences that this excitonic behavior is derived mainly from nonmagnetic quadrupolar interactions. Furthermore, the narrowing of the linewidths of the excitations below the superconducting transition temperature indicates the close connection between the superconductivity and the excitons.

Program POD; A Computer code to calculate nuclear elastic scattering cross sections with the optical model and neutron inelastic scattering cross sections by the distorted-wave Born approximation

Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Iwamoto, Osamu; Shibata, Keiichi; Nakagawa, Tsuneo; Fukahori, Tokio; Katakura, Junichi

JAERI-Data/Code 2005-004, 54 Pages, 2005/07

JAERI-Data-Code-2005-004.pdf:1.63MB

The computer code, POD, was developed to calculate angle-differential cross sections and analyzing powers for shape-elastic scattering for collisions of neutron or light ions with target nucleus. The cross sections are computed with the optical model. Angle-differential cross sections for neutron inelastic scattering can also be calculated with the distorted-wave Born approximation. The optical model potential parameters are the most essential inputs for those model computations. The cross sections and analyzing powers are obtained by using the existing local or global parameters. The parameters can also be inputted by users. In this report, the theoretical formulas, the computational methods, and the input parameters are explained. The sample inputs and outputs are also presented.

Lattice dynamics of methane hydrate

Yamauchi, Hiroki; Igawa, Naoki; Ishii, Yoshinobu

Proceedings of 5th International Conference on Gas Hydrates (ICGH-5), Volume 5, p.1615 - 1618, 2005/06

Inelastic neutron scattering experiments were carried out on powdered methane hydrate. In order to observe the precise spectra inelastic neutron scattering without the influence of incoherent contribution, the fully deuterated sample was used for the measurements. The relatively clear excitation peaks were observed at about 6.5 meV and 10 meV mainly corresponding to the transverse acoustic modes and exhibited only very little temperature dependence at 10 K and 100 K. On the other hand, the small shoulder found around 4 meV at 10 K showed apparent temperature dependence. The scattering intensity of this shoulder appeared to broaden and decrease at 100 K, which can be attributed to the increasing anharmonic contribution to the translational motion of the methane molecules encaged in the large cages.

CRYOPAD on the triple-axis spectrometer TAS-1 at JAERI

Takeda, Masayasu; Nakamura, Mitsutaka; Kakurai, Kazuhisa; Lelivre-Berna, E.*; Tasset, F.*; Regnault, L.-P.*

Physica B; Condensed Matter, 356(1-4), p.136 - 140, 2005/02

https://doi.org/10.1016/j.physb.2004.10.064

It is now well known that CRYOPAD (CRYOgenic Polarization Analysis Device) is a powerful device which enables us to investigate the spherical changes of neutron-spin polarization in the scattering processes of magnetic materials. ILL and CEA-Grenoble, in the framework of EC/ENPI, and JAERI, in the framework of the MoU between ILL and ASRC JAERI, initiated to assemble three third generation CRYOPADs at ILL (CRYOPADUM project), optimized both for elastic and inelastic neutron scattering. One is installed on the ILL instrument D3 (Millennium Project) and the other on the CEA-Grenoble instrument IN22. The JAERI CRYOPADUM is installed on the triple-axis spectrometer TAS-1 at JRR-3 and is now in commissioning with powerful data acquisition software implanted from D3. We present the status of the CRYOPADUM on TAS-1 at JAERI and describe some of the planned experiments.

Phonon anomaly on NaHfNCl superconductors with =22 K

Shamoto, Shinichi; Hirai, Atsuo*; Yamanaka, Shoji*; Aso, Naofumi*; Kajitani, Tsuyoshi*

Journal of Neutron Research, 12(4), p.295 - 300, 2004/12

https://doi.org/10.1080/10238160412331299474

Inelastic neutron scattering measurements have been performed on superconducting NaHfNCl powder samples with x=0.27 and 0.38 (T =22 K). We have observed several temperature dependent phonon anomalies, e.g., at E=15, 29, 76, and 81 meV for the former sample. A phonon peak with E=14.5 meV at Q=6 increases for both samples with decreasing temperature below T=40 K, which is much higher than T. The phonon peak is assigned to an ab-plane vibrational mode, E, of chlorine and hafnium atoms, which strongly modifies the electronic band structure. The phonon anomaly is discussed in terms of carrier inhomogeneity.

Inelasticity effect on neutron scattering intensities of the null-HO

Kameda, Yasuo*; Sasaki, Motoya*; Usuki, Takeshi*; Otomo, Toshiya*; Ito, Keiji*; Suzuya, Kentaro; Fukunaga, Toshiharu*

Journal of Neutron Research, 11(3), p.153 - 163, 2003/09

https://doi.org/10.1080/10238160310001657817

We describe results of time-of-flight (TOF) neutron diffraction of the liquid water null-HO in order to investigate the effect of both the scattering angle and the neutron flight path ratio to the observed self-scattering intensities. An empirical inelasticity correction procedure is proposed using the self-scattering intensity observed for the null-HO.