Iida, Kazuki*; Yoshida, Hiroyuki*; Nakao, Akiko*; Jeschke, H. O.*; Iqbal, Y.*; Nakajima, Kenji; Kawamura, Seiko; Munakata, Koji*; Inamura, Yasuhiro; Murai, Naoki; et al.
Physical Review B, 101(22), p.220408_1 - 220408_6, 2020/06
Crystal and magnetic structures of the mineral centennialite CaCu(OD)Cl 0.6DO are investigated by means of synchrotron X-ray diffraction and neutron diffraction measurements complemented by density functional theory (DFT) and pseudofermion functional renormalization group (PFFRG) calculations. In CaCu(OD)Cl 0.6DO, Cu ions form a geometrically perfect kagome network with antiferromagnetic . No intersite disorder between Cu and Ca ions is detected. CaCu(OD)Cl 0.6DO enters a magnetic long-range ordered state below = 7.2 K, and the =0 magnetic structure with negative vector spin chirality is obtained. The ordered moment at 0.3 K is suppressed to 0.58(2)B. Our DFT calculations indicate the presence of antiferromagnetic and ferromagnetic superexchange couplings of a strength which places the system at the crossroads of three magnetic orders (at the classical level) and a spin- PFFRG analysis shows a dominance of =0 type magnetic correlations, consistent with and indicating proximity to the observed =0 spin structure. The results suggest that this material is located close to a quantum critical point and is a good realization of a -- kagome antiferromagnet.
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) and actinides (5) provide variety of interesting states realized with competing interactions between the increasing number of electrons. Since crystal field splitting of many-body 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 electron states of heavy electron compounds NpPdAl and actinide and rare earth based iso-structural family.
Kaneko, Koji; Cheung, Y. W.*; Hu, Y.*; Imai, Masaki*; Tanioku, Yasuaki*; Kanagawa, Hibiki*; Murakawa, Joichi*; Moriyama, Kodai*; Zhang, W.*; Lai, K. T.*; et al.
JPS Conference Proceedings (Internet), 30, p.011032_1 - 011032_6, 2020/03
Wo, H.*; Wang, Q.*; Shen, Y.*; Zhang, X.*; Hao, Y.*; Feng, Y.*; Shen, S.*; He, Z.*; Pan, B.*; Wang, W.*; et al.
Physical Review Letters, 122(21), p.217003_1 - 217003_5, 2019/05
Kaneko, Koji; Frontzek, M. D.*; Matsuda, Masaaki*; Nakao, Akiko*; Munakata, Koji*; Ohara, Takashi; Kakihana, Masashi*; Haga, Yoshinori; Hedo, Masato*; Nakama, Takao*; et al.
Journal of the Physical Society of Japan, 88, p.013702_1 - 013702_5, 2019/01
Metoki, Naoto; Haga, Yoshinori; Yamamoto, Etsuji; Matsuda, Masaaki*
Journal of the Physical Society of Japan, 87(11), p.114712_1 - 114712_9, 2018/11
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.
Metoki, Naoto; Yamauchi, Hiroki; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Hagihala, Masato*; Masuda, Takatsugu*; Aczel, A. A.*; Chi, S.*; Hong, T.*; Matsuda, Masaaki*; et al.
Journal of the Physical Society of Japan, 87(9), p.094704_1 - 094704_8, 2018/09
The -electron states of PrPdAl were revealed by neutron inelastic scattering. The flat -orbitals with large become stable under the two-dimensional CEF potential of unique crystal structure, which is the origin of the Ising anisotropy. A systematic understanding is possible in RPdAl based on this CEF potential. Especially the -type anisotropy in NpPdAl can be qualitatively understood with the positive Stevens factors. It mean that the local property is important for the physical properties of RPdAl including the heavy fermion superconductivity in NpPdAl.
Metoki, Naoto; Yamauchi, Hiroki; Matsuda, Masaaki*; Fernandez-Baca, J. A.*; Watanuki, Ryuta*; Hagiwara, Masato*
Physical Review B, 97(17), p.174416_1 - 174416_10, 2018/05
Neutron polarization analysis has been carried out in order to clarify the magnetic structure of multiple order parameter -electron system NdB. We confirmed the non-collinear "all-in all-out" structure () of the in-plane moment. We found that the magnetic moment along the -axis showed diagonally antiferromagnetic structure (). The unusual magnetic ordering is phenomenologically understood via Landau theory. We also found that a long-period incommensurate modulation of the () antiferromagnetic structure of with the propagation = (0.14, 0.14, 0.1) and = (0.2, 0, 0.1) in phase III and IV, respectively. It is clear that the multipole degree-of-freedom based on pseudo-quartet -electron state play important role.
Matsuda, Norihiro; Izumi, Yuichi*; Yamanaka, Yoshiyuki*; Gando, Toshiyuki*; Yamada, Masaaki*; Oishi, Koji*
EPJ Web of Conferences, 153, p.07001_1 - 07001_6, 2017/09
Meigo, Shinichiro; Nishikawa, Masaaki; Iwamoto, Hiroki; Matsuda, Hiroki
EPJ Web of Conferences, 146, p.11039_1 - 11039_4, 2017/09
no abstracts in English
Matsuda, Masaaki*; Onishi, Hiroaki; Okutani, Akira*; Ma, J.*; Agrawal, H.*; Hong, T.*; Pajerowski, D. M.*; Copley, J. R. D.*; Okunishi, Koichi*; Mori, Michiyasu; et al.
Physical Review B, 96(2), p.024439_1 - 024439_8, 2017/07
Metoki, Naoto; Yamauchi, Hiroki; Kitazawa, Hideaki*; Suzuki, Hiroyuki*; Hagihala, Masato*; Frontzek, M. D.*; Matsuda, Masaaki*; Fernandez-Baca, J. A.*
Journal of the Physical Society of Japan, 86(3), p.034710_1 - 034710_5, 2017/03
Magnetic structure of NdPdAl has been studied by means of neutron powder diffraction. We observed remarkable magnetic reflections with the modulation vector = (1/2 0 0) below the ordering temperature = 1.2 K. We found a collinear magnetic structure of Nd moment of 2.9(1) at 0.3 K parallel to the -axis, where the ferromagnetically ordered planes stack with four Nd layer period of ++-- sequence along the direction with the distance between adjuscent Nd layers to be . This is very similar to CePdAl with = (0.23 0.23 0) and the Ce moment parallel to the -axis. These structures with in-plane modulation is a consequence of the two dimensional nature of fermi surface topology in this family, coming from unique crystal structure with very long tetragonal unit cell and large distance 7 between the rare earth layers separated by Al and two Pd layers.
Yu, R.*; Hojo, Hajime*; Watanuki, Tetsu; Mizumaki, Masaichiro*; Mizokawa, Takashi*; Oka, Kengo*; Kim, H.*; Machida, Akihiko; Sakaki, Koji*; Nakamura, Yumiko*; et al.
Journal of the American Chemical Society, 137(39), p.12719 - 12728, 2015/10
no abstracts in English
Kobayashi, Riki*; Kaneko, Koji; Saito, Kotaro*; Mignot, J.-M.*; Andr, G.*; Robert, J.*; Wakimoto, Shuichi; Matsuda, Masaaki*; Chi, S.*; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 83(10), p.104707_1 - 104707_5, 2014/10
Hase, Masashi*; Dnni, A.*; Ozawa, Kiyoshi*; Kitazawa, Hideaki*; Sakai, Osamu*; Pomjakushin, V. Y.*; Keller, L.*; Kaneko, Koji; Metoki, Naoto; Kakurai, Kazuhisa; et al.
Journal of Physics; Conference Series, 340, p.012066_1 - 012066_7, 2012/00
We determined the magnetic structure below K of the spin-5/2 antiferromagnetic (AF) trimer substance SrMnPO using neutron powder diffraction experiments. The incommensurate propagation vector is expressed as [0, , 0], due to competition between the nearest-neighbor and next-nearest-neighbor interactions in trimerized chains. The value of is 0.316 to 0.331, changing rapidly at K. We confirmed that the intra-trimer interaction is AF. The magnetic excitation peaks were obsereved at 0.46, 0.68, and 1.02 meV. The weak Q dependence indicates the discrete energy levels, which do not contradict the AF trimer model with the intra-trimer interaction value of 0.29 meV (3.4 K).
Hase, Masashi*; Matsuda, Masaaki*; Kaneko, Koji; Metoki, Naoto; Kakurai, Kazuhisa; Yang, T.*; Cong, R.*; Lin, J.*; Ozawa, Kiyoshi*; Kitazawa, Hideaki*
Physical Review B, 84(21), p.214402_1 - 214402_6, 2011/12
Okuda, Tetsuji*; Uto, Kazuma*; Seki, Shinichiro*; Onose, Yoshinori*; Tokura, Yoshinori*; Kajimoto, Ryoichi; Matsuda, Masaaki*
Journal of the Physical Society of Japan, 80(1), p.014711_1 - 014711_7, 2011/04
Okazaki, Ryuji*; Shimozawa, Masaaki*; Shishido, Hiroaki*; Konczykowski, M.*; Haga, Yoshinori; Matsuda, Tatsuma; Yamamoto, Etsuji; Onuki, Yoshichika; Yanase, Yoichi*; Shibauchi, Takasada*; et al.
Journal of Physics; Conference Series, 273, p.012081_1 - 012081_4, 2011/02
Matsuda, Masaaki; Fujita, Masaki*; Takeda, Masayasu; Kakurai, Kazuhisa; Yamada, Kazuyoshi*
Physica C, 470(Suppl.1), p.S82 - S83, 2010/12
Okazaki, Ryuji*; Konczykowski, M.*; Van der Beek, C. J.*; Kato, Tomonari*; Hashimoto, Kenichiro*; Shimozawa, Masaaki*; Shishido, Hiroaki*; Yamashita, Minoru*; Ishikado, Motoyuki; Kito, Hijiri*; et al.
Physica C, 470(Suppl.1), p.S485 - S486, 2010/12
We report the lower critical fields measurements on Fe-based oxipnictide PrFeAsO single crystals for and -planes. To avoid the difficulty of determinations due to the flux pinning, we developed a novel method using a miniature hall-sensor array which can evaluate the local magnetic induction ai each sensor position. The hall sensor which is placed on the edge of the crystal clearly resolves the first flux penetration from the Meissner state. The temperature dependence of for is well scaled by the in-plane penetration depth and is consistent with a full-gap superconducting state. The anistropy of at low temperatures is estimated to be 3, which is much smaller than of . This indicates the multiband superconductivity, in which the active bands for superconductivity are more two-dimensional.