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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：4 Percentile：39.25(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.
Cu(PO)SO 5HO as a model antiferromagnetic spin-1/2 Heisenberg 
- chainFujihara, Masayoshi; Jeschke, H. O.*; Morita, Katsuhiro*; Kuwai, Tomohiko*; Koda, Akihiro*; Okabe, Hirotaka*; Matsuo, Akira*; Kindo, Koichi*; Mitsuda, Setsuo*
Physical Review Materials (Internet), 6(11), p.114408_1 - 114408_8, 2022/11
Times Cited Count：3 Percentile：22.62(Materials Science, Multidisciplinary)
= 1/2 Heisenberg - chain antiferromagnets have been investigated extensively due to their exotic magnetic states. Here, we report the magnetic behavior of birchite CdCu(PO)SO5HO and its effective spin model. Experimental studies by magnetic susceptibility, magnetization, heat capacity, and 
SR measurements indicate the absence of long-range order down to 0.4 K. Theoretical studies reveal that birchite is a model compound for the - antiferromagnetic chain: the intrachain interactions and are antiferromagnetic and their magnitude is about 100 times larger than the interchain interactions. The magnitude of is two to three times larger than that of , thus the spin gap is expected to be only a few percent of that of . The temperature dependence of the specific heat shows a broad peak at about 1 K (
0.036 ), which suggests the presence of a spin gap.
Fujihara, Masayoshi*; Morita, Katsuhiro*; Mole, R.*; Mitsuda, Setsuo*; Toyama, Takami*; Yano, Shinichiro*; Yu, D.*; Sota, Shigetoshi*; Kuwai, Tomohiko*; Koda, Akihiro*; et al.
Nature Communications (Internet), 11, p.3429_1 - 3429_7, 2020/07
Times Cited Count：57 Percentile：92.76(Multidisciplinary Sciences)Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.
Nuclear Instruments and Methods in Physics Research B, 272, p.49 - 52, 2012/02
Times Cited Count：10 Percentile：57.02(Instruments & Instrumentation)Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.
Journal of Nuclear Materials, 408(2), p.201 - 204, 2011/01
Times Cited Count：14 Percentile：69.17(Materials Science, Multidisciplinary)Inami, Toshiya; Michimura, Shinji; Mitsuda, Akihiro*; Wada, Hirofumi*
Physical Review B, 82(19), p.195133_1 - 195133_5, 2010/11
Times Cited Count：11 Percentile：44.06(Materials Science, Multidisciplinary)Two first-order phase transitions of the valence-fluctuating compound EuPtP at 
=246 K and 
=200 K were examined by means of resonant X-ray diffraction at the Eu 
absorption edge. Although previous M
ssbauer spectroscopy and preliminary X-ray diffraction experiments have suggested charge ordered states, characteristic energy spectra of the 111 and 11
reflections observed in the present experiment unambiguously indicated that twofold and threefold superstructures of Eu valence exist below and between and , respectively. We also propose a mechanism to explain the charge ordering in EuPtP based on a charge-lattice coupling that alters a Coulomb repulsion.
Matsuda, Yasuhiro*; Her, J. L.*; Inami, Toshiya; Owada, Kenji; Ouyang, Z. W.*; Okada, Kyoko*; Nojiri, Hiroyuki*; Mitsuda, Akihiro*; Wada, Hirofumi*; Yoshimura, Kazuyoshi*; et al.
Journal of Physics; Conference Series, 190, p.012019_1 - 012019_6, 2009/11
Times Cited Count：8 Percentile：86.28(Physics, Condensed Matter)Matsuda, Yasuhiro*; Ouyang, Z. W.*; Nojiri, Hiroyuki*; Inami, Toshiya; Owada, Kenji; Suzuki, Motohiro*; Kawamura, Naomi*; Mitsuda, Akihiro*; Wada, Hirofumi*
Physical Review Letters, 103(4), p.046402_1 - 046402_4, 2009/07
Times Cited Count：55 Percentile：86.71(Physics, Multidisciplinary)X-ray magnetic circular dichroism (XMCD) at the Eu L edge in two compounds exhibiting valence fluctuation, namely EuNi
(Si
Ge
) and EuNiP, has been investigated at high magnetic fields of up to 40T. A distinct XMCD peak corresponding to the trivalent state (Eu
), whose ground state is nonmagnetic (J = 0), was observed in addition to the main XMCD peak corresponding to the magnetic (J = 7/2) divalent state (Eu
). This result indicates that the 5
electrons belonging to both valence states are magnetically polarized. It was also found that the ratio 
(3+)/(2+) between the polarization of 5 electrons() in the Eu state and that of Eu depends on the material. The possible origin of the XMCD and an explanation of the material dependence of (3+)/(2+) are discussed in terms of hybridization between the conduction electrons and the f electrons.
Al developmentTakeuchi, Takao*; Kikuchi, Akihiro*; Banno, Nobuya*; Kitaguchi, Hitoshi*; Iijima, Yasuo*; Tagawa, Kohei*; Nakagawa, Kazuhiko*; Tsuchiya, Kiyosumi*; Mitsuda, Shiori*; Koizumi, Norikiyo; et al.
Cryogenics, 48(7-8), p.371 - 380, 2008/07
Times Cited Count：65 Percentile：87.84(Thermodynamics)NbAl has advantages of better tolerance to strain/stress and a higher critical magnetic field (30 T at 4.2 K) for stoichiometric composition over NbSn. The rapid-heating, quenching and transformation annealing (RHQT) process enables to form a stoichiometric NbAl with fine grain structures via metastable bcc supersaturated-solid-solution. As a result a large critical current density of NbAl is achieved over the whole range of magnetic fields without trading off the excellent strain tolerance. A long-length of RHQ processing has been established, and a rectangular but Cu stabilized NbAl strand is about be commercially available for NMR uses. Ag or Cu internal stabilization and Cu ion-plating/electroplating techniques have been also developed to enable the stabilized round wire for accelerator and fusion magnets. Successfully energized test coils that were manufactured with a wind-and-react technique have demonstrated that a long piece of Cu stabilized RHQT NbAl wire is really available for practical applications.
(Si
Ge
)Matsuda, Yasuhiro*; Inami, Toshiya; Owada, Kenji; Murata, Yuto*; Nojiri, Hiroyuki*; Murakami, Yoichi*; Mitsuda, Akihiro*; Wada, Hirofumi*; Miyazaki, Hiroshi*; Harada, Isao*
Journal of the Physical Society of Japan, 77(5), p.054713_1 - 054713_7, 2008/05
Times Cited Count：26 Percentile：74.17(Physics, Multidisciplinary)The magnetic-field-induced valence transition in EuNi(SiGe) (x=0.82, 0.85) has been studied by X-ray absorption spectroscopy at low temperatures. The field dependence of the Eu valence is directly observed for the first time. We find a significant decrease in the valences at high magnetic fields above 40 T. The valence of Eu changes from v = 2.75 at a zero field to v = 2.33 at 40 T for x = 0.82. The results are analyzed using a theoretical model. The hybridization parameter V between the Eu and Eu states and the energy separation 
are determined, which are crucial for quantum mechanical mixing.
Matsuda, Yasuhiro*; Murata, Yuto*; Inami, Toshiya; Owada, Kenji; Nojiri, Hiroyuki*; Oyama, Kenji*; Kato, Naoki*; Murakami, Yoichi*; Iga, Fumitoshi*; Takabatake, Toshiro*; et al.
Journal of Physics; Conference Series, 51, p.490 - 493, 2006/00
Times Cited Count：8 Percentile：91.77(Physics, Condensed Matter)SiInami, Toshiya; Ishii, Kenji; Yoshida, Masahiro; Mitsuda, Akihiro*; Taguchi, Munetaka*; Shin, S.*
no journal, ,
no abstracts in English
Inami, Toshiya; Michimura, Shinji; Mitsuda, Akihiro*; Wada, Hirofumi*
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no abstracts in English
Si, 2Inami, Toshiya; Ishii, Kenji; Jarrige, I.; Mitsuda, Akihiro*
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no abstracts in English
SiInami, Toshiya; Ishii, Kenji; Jarrige, I.; Yoshida, Masahiro; Mitsuda, Akihiro*
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SiInami, Toshiya; Ishii, Kenji; Jarrige, I.*; Yoshida, Masahiro*; Mitsuda, Akihiro*
no journal, ,
X-ray absorption spectroscopy at the lanthanoid 
- and 
-edges is a versatile tool for investigating valency, spatial symmetry and hybridization of the 
electrons. A disadvantage of this technique, however, is the very short penetration length of soft X-rays in solid materials. X-ray Raman scattering (XRS) is an alternative method to obtain absorption spectra. High energy incident X-rays transfer a part of their energy to various excitations and the obtained energy-loss spectrum corresponds to an absorption spectrum. Because of the high penetration depth of hard X-rays, this technique is truly bulk sensitive. Here we report on a feasibility study of XRS experiments applied to a mixed-valent f-electron system. The test sample was EuPdSi, which exhibits a sharp and large valence transition around 150 K. The obtained XRS spectra showed clear absorption features at the - and -edges. However, we did not detect any difference between the spectra at 10 K and 200 K.
HOFujihara, Masayoshi; Morita, Katsuhiro*; Mitsuda, Setsuo*; Okabe, Hirotaka*; Koda, Akihiro*; Murai, Naoki; Hagihara, Masato
no journal, ,
no abstracts in English
Inami, Toshiya; Michimura, Shinji; Mitsuda, Akihiro*; Wada, Hirofumi*
no journal, ,
Mitsuda, Tomoaki*; Iwase, Akihiro*; Saito, Yuichi
no journal, ,
no abstracts in English
