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OFujihara, Masayoshi; Hagihara, Masato; Morita, Katsuhiro*; Murai, Naoki; Koda, Akihiro*; Okabe, Hirotaka*; Mitsuda, Setsuo*
Physical Review B, 107(5), p.054435_1 - 054435_8, 2023/02
Times Cited Count：0 Percentile：0.01(Materials Science, Multidisciplinary)The 
= 1/2 Heisenberg linear chain antiferromagnet is the simplest spin model; nevertheless it serves as a platform for various quantum many-body phenomena. Here, we report the magnetic behavior of a quasi-one-dimensional antiferromagnet KCuPOHO. A long-range commensurate antiferromagnetic order with ordered moment 0.31(1) 
per spin occurs at 
= 11.7(1) K. Above , the inelastic neutron excitation is characterized by a two spinon continuum. The intrachain interaction 
and interchain interaction 
are estimated to be 172 K and 4.25(4) K, respectively; thus the ratio of the / = 0.0247(3). At lower energies, below , a spin gap is observed in the dispersive excitations. These results are consistent with characteristics observed in weakly interacting = 1/2 Heisenberg chain system.
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
Times Cited Count：0 Percentile：0.02(Physics, Multidisciplinary)Ishii, Yui*; Yamamoto, Arisa*; Sato, Naoki*; Nambu, Yusuke*; Kawamura, Seiko; Murai, Naoki; Ohara, Koji*; Kawaguchi, Shogo*; Mori, Takao*; Mori, Shigeo*
Physical Review B, 106(13), p.134111_1 - 134111_7, 2022/10
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)
Chen, L.*; Mao, C.*; Chung, J.-H.*; Stone, M. B.*; Kolesnikov, A. I.*; Wang, X.*; Murai, Naoki; Gao, B.*; Delaire, O.*; Dai, P.*
Nature Communications (Internet), 13, p.4037_1 - 4037_7, 2022/07
Times Cited Count：1 Percentile：0(Multidisciplinary Sciences)Nakajima, Kenji; Kawamura, Seiko; Kofu, Maiko; Murai, Naoki; Inamura, Yasuhiro; Kikuchi, Tatsuya*; Wakai, Daisuke*
JPS Conference Proceedings (Internet), 33, p.011089_1 - 011089_7, 2021/03
The recent update of AMATERAS, a cold-neutron disk-chopper spectrometer at Japan Proton Accelerator Research Complex (J-PARC), is reported. AMATERAS has been operating for a decade. Since 2017, some updates have been done or are underway, which include installing new detectors, replacing the vacuum system of the scattering chamber, and other works. We are also working on the re-investigation of the resolution function. Demonstration measurements were carried out at 1MW test operations done in 2018 and 2019. Plans of upgrading the spectrometer are currently being considered.
Hao, Y. Q.*; Wo, H. L.*; Gu, Y. M.*; Zhang, X. W.*; Gu, Y. Q.*; Zheng, S. Y.*; Zhao, Y.*; Xu, G. Y.*; Lynn, J. W.*; Nakajima, Kenji; et al.
Science China; Physics, Mechanics & Astronomy, 64(3), p.237411_1 - 237411_6, 2021/03
Times Cited Count：3 Percentile：42.28(Physics, Multidisciplinary)
=0 long-range magnetic order in centennialite CaCu(OD)
Cl 0.6DO; A Spin-
perfect kagome antiferromagnet with 
-
-
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
Times Cited Count：18 Percentile：83.65(Materials Science, Multidisciplinary)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.
RuO
proved by spin resonanceIida, Kazuki*; Kofu, Maiko; Suzuki, Katsuhiro*; Murai, Naoki; Kawamura, Seiko; Kajimoto, Ryoichi; Inamura, Yasuhiro; Ishikado, Motoyuki*; Hasegawa, Shunsuke*; Masuda, Takatsugu*; et al.
Journal of the Physical Society of Japan, 89(5), p.053702_1 - 053702_5, 2020/05
Times Cited Count：15 Percentile：81.95(Physics, Multidisciplinary)Murai, Naoki; Fukuda, Tatsuo; Nakajima, Masamichi*; Kawamura, Mitsuaki*; Ishikawa, Daisuke*; Tajima, Setsuko*; Baron, A. Q. R.*
Physical Review B, 101(3), p.035126_1 - 035126_6, 2020/01
Times Cited Count：5 Percentile：42.55(Materials Science, Multidisciplinary)We report an inelastic X-ray scattering investigation of phonons in FeSe superconductor. Comparing the experimental phonon dispersion with density functional theory (DFT) calculations in the non-magnetic state, we found a significant disagreement between them. A better overall agreement was obtained by allowing for spin-polarization in DFT calculations, despite the absence of magnetic order in FeSe. This calculation gives a realistic approximation, at DFT level, of the disordered paramagnetic state of FeSe, in which strong spin fluctuations are present.
K
FeAsIdeta, Shinichiro*; Murai, Naoki; Nakajima, Masamichi*; Kajimoto, Ryoichi; Tanaka, Kiyohisa*
Physical Review B, 100(23), p.235135_1 - 235135_7, 2019/12
Times Cited Count：1 Percentile：5.87(Materials Science, Multidisciplinary)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：12.96(Physics, Condensed Matter)
MoO
( = In, Sc)Iida, Kazuki*; Yoshida, Hiroyuki*; Okabe, Hirotaka*; Katayama, Naoyuki*; Ishii, Yuto*; Koda, Akihiro*; Inamura, Yasuhiro; Murai, Naoki; Ishikado, Motoyuki*; Kadono, Ryosuke*; et al.
Scientific Reports (Internet), 9(1), p.1826_1 - 1826_9, 2019/02
Times Cited Count：6 Percentile：53.31(Multidisciplinary Sciences)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：3 Percentile：90.78
K
FeAs as seen via time-of-flight inelastic neutron scatteringMurai, Naoki; Suzuki, Katsuhiro*; Ideta, Shinichiro*; Nakajima, Masamichi*; Tanaka, Kiyohisa*; Ikeda, Hiroaki*; Kajimoto, Ryoichi
Physical Review B, 97(24), p.241112_1 - 241112_6, 2018/06
Times Cited Count：5 Percentile：29.23(Materials Science, Multidisciplinary)We use inelastic neutron scattering (INS) to investigate the effect of electron correlations on spin dynamics in iron-based superconductor BaKFeAs. Our INS data show a spin-wave-like dispersive feature, with a zone boundary energy of 200 meV. A first principles analysis of dynamical spin susceptibility, incorporating the mass renormalization factor of 3, as determined by angle-resolved photoemission spectroscopy, provides a reasonable description of the observed spin excitations. This analysis shows that electron correlations in the Fe-3d bands yield enhanced effective electron masses, and consequently, induce substantial narrowing of the spin excitation bandwidth. Our results highlight the importance of electron correlations in an itinerant description of the spin excitations in iron-based superconductors.
studied by neutron scattering and their relation with thermal conductivitiesKajimoto, Ryoichi; Nakamura, Mitsutaka; Murai, Naoki; Shamoto, Shinichi; Honda, Takashi*; Ikeda, Kazutaka*; Otomo, Toshiya*; Hata, Hiroto*; Eto, Takahiro*; Noda, Masaaki*; et al.
Scientific Reports (Internet), 8(1), p.9651_1 - 9651_8, 2018/06
Times Cited Count：5 Percentile：29.23(Multidisciplinary Sciences)AsIida, Kazuki*; Ishikado, Motoyuki*; Nagai, Yuki; Yoshida, Hiroyuki*; Christianson, A. D.*; Murai, Naoki; Kawashima, Kenji*; Yoshida, Yoshiyuki*; Eisaki, Hiroshi*; Iyo, Akira*
Journal of the Physical Society of Japan, 86(9), p.093703_1 - 093703_4, 2017/09
Times Cited Count：23 Percentile：81.4(Physics, Multidisciplinary)As using high-resolution inelastic X-ray scatteringMurai, Naoki*; Fukuda, Tatsuo; Kobayashi, Tatsuya*; Nakajima, Masamichi*; Uchiyama, Hiroshi*; Ishikawa, Daisuke*; Tsutsui, Satoshi*; Nakamura, Hiroki; Machida, Masahiko; Miyasaka, Shigeki*; et al.
Physical Review B, 93(2), p.020301_1 - 020301_5, 2016/01
Times Cited Count：7 Percentile：36.32(Materials Science, Multidisciplinary)As via inelastic X-ray scatteringMurai, Naoki*; Fukuda, Tatsuo; Uchiyama, Hiroshi*; Tsutsui, Satoshi*; Ishikawa, Daisuke*; Kobayashi, Tatsuya*; Nakamura, Hiroki; Machida, Masahiko; Nakajima, Masamichi*; Miyasaka, Shigeki*; et al.
no journal, ,
no abstracts in English
Co
)As by inelastic X-ray scatteringMurai, Naoki*; Fukuda, Tatsuo; Nakajima, Masamichi*; Kobayashi, Tatsuya*; Uchiyama, Hiroshi*; Tsutsui, Satoshi*; Ishikawa, Daisuke*; Nakamura, Hiroki; Machida, Masahiko; Miyasaka, Shigeki*; et al.
no journal, ,
As via high-resolution inelastic X-ray scatteringMurai, Naoki; Fukuda, Tatsuo; Kobayashi, Tatsuya*; Nakajima, Masamichi*; Uchiyama, Hiroshi*; Ishikawa, Daisuke*; Tsutsui, Satoshi*; Nakamura, Hiroki; Machida, Masahiko; Miyasaka, Shigeki*; et al.
no journal, ,
We report the first IXS study of single crystals of SrFeAs that have been detwinned via application of in-plane uniaxial stress. Our results clearly show anisotropy in phonon structure below 
= 
characterized by mode splitting at tetragonally-equivalent momentum transfers. To the best of our knowledge, this is the first observation of phonon anisotropy in iron-pnictides at finite momentum transfers. We obtain good agreement with our results using calculations that are modified to account for a reduced magnetic moment and fluctuating magnetism. Previous efforts using either non-magnetic calculations or static magnetism tend to either get the dispersion wrong from non-magnetic calculations or strongly over-estimate the phonon mode splitting when static magnetism is included. Our model for the response below incorporates a phenomenological reduction in force constant anisotropy, by about 65%, that can be attributed to residual fast magnetic fluctuations. Above , all fluctuations are assumed to be fast and the response becomes the average of the results from the static magnetism. This serves as a starting point for a general model of phonons in iron-pnictides applicable to both non-magnetic and magnetic phases.
