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Journal Articles

Q dependence of magnetic resonance mode on FeTe$$_{0.5}$$Se$$_{0.5}$$ studied by inelastic neutron scattering

Ishikado, Motoyuki*; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Ji, S.*; Arai, Masatoshi*; Shamoto, Shinichi

Condensed Matter (Internet), 4(3), p.69_1 - 69_10, 2019/09

The enhancement magnetic resonance mode of FeTe$$_{0.5}$$Se$$_{0.5}$$ is limited around Q = ($$pi$$, 0). Q dependence is found to be consistent with a theoretical simulation of the magnetic resonance mode with the sign-reversing order parameter of s$$pm$$wave.

Journal Articles

Local disorder in proton conductor BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ analyzed by neutron diffraction/ atomic pair distribution function

Igawa, Naoki; Kodama, Katsuaki; Taguchi, Tomitsugu*; Yoshida, Yukihiko*; Matsukawa, Takeshi*; Hoshikawa, Akinori*; Ishigaki, Toru*

Transactions of the Materials Research Society of Japan, 43(6), p.329 - 332, 2018/12

For the understanding of the crystal structural effect on the electrical properties, the local disorder in BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ which is one of the excellent proton conductors for solid oxide fuel cells was estimated by using the Atomic Pair Distribution Function (PDF) analysis method with the neutron diffraction. The local structure is almost the same as the average structure which was estimated by the Rietveld analysis using the cubic crystal structure (space group, $${it Pm}$$$$overline{3}$$$${it m}$$) in the atomic distance range of ${it r}$ $$>$$ 6${AA}$. The PDF profile was fitted better using the tetragonal crystal structure with the space group of ${it P}$4/${it mmm}$ than those with $${it Pm}$$$$overline{3}$$$${it m}$$ in the range ${it r}$ $$<$$ 6${AA}$. Those results indicate the presence of the local disorder in the lattice. In this work, the relationship between the average and local structures of BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ will be discussed.

Journal Articles

High-energy spin fluctuation in low-T$$_{c}$$ iron-based superconductor LaFePO$$_{0.9}$$

Ishikado, Motoyuki*; Shamoto, Shinichi; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Hong, T.*; Mutka, H.*

Scientific Reports (Internet), 8, p.16343_1 - 16343_6, 2018/11

 Times Cited Count:2 Percentile:60.51(Multidisciplinary Sciences)

Spin fluctuations are widely believed to play an important role as one of the most possible mechanisms for unconventional high-temperature superconductors. Here, the spin fluctuation in LaFePO$$_{0.9}$$ is found at high energies such as 30-50 meV with comparable intensity to an optimally doped LaFeAs(O,F).

Journal Articles

Nanoscale ice-type structural fluctuation in spinel titanates

Torigoe, Shuhei*; Hattori, Takayuki*; Kodama, Katsuaki; Honda, Takashi*; Sagayama, Hajime*; Ikeda, Kazutaka*; Otomo, Toshiya*; Nitani, Hiroaki*; Abe, Hitoshi*; Murakawa, Hiroshi*; et al.

Physical Review B, 98(13), p.134443_1 - 134443_7, 2018/10

Journal Articles

Neutron scattering study of yttrium iron garnet

Shamoto, Shinichi; Ito, Takashi; Onishi, Hiroaki; Yamauchi, Hiroki; Inamura, Yasuhiro; Matsuura, Masato*; Akatsu, Mitsuhiro*; Kodama, Katsuaki; Nakao, Akiko*; Moyoshi, Taketo*; et al.

Physical Review B, 97(5), p.054429_1 - 054429_9, 2018/02

 Times Cited Count:5 Percentile:46.38(Materials Science, Multidisciplinary)

Nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y$$_3$$Fe$$_5$$O$$_{12}$$ have been studied by neutron scattering. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of $$q$$-integrated dynamical spin susceptibility $$chi$$"($$E$$) exhibits a square-root energy-dependence in the low energies. The magnon density of state is estimated from the $$chi$$"($$E$$) obtained on an absolute scale. The value is consistent with a single chirality mode for the magnon branch expected theoretically.

Journal Articles

Alternative equation on magnetic pair distribution function for quantitative analysis

Kodama, Katsuaki; Ikeda, Kazutaka*; Shamoto, Shinichi; Otomo, Toshiya*

Journal of the Physical Society of Japan, 86(12), p.124708_1 - 124708_8, 2017/12

 Times Cited Count:2 Percentile:66.91(Physics, Multidisciplinary)

Journal Articles

Local structural analysis of half-metallic ferromagnet CrO$$_2$$

Kodama, Katsuaki; Ikeda, Kazutaka*; Isobe, Masahiko*; Takeda, Hikaru*; Ito, Masayuki*; Ueda, Yutaka*; Shamoto, Shinichi; Otomo, Toshiya*

Journal of the Physical Society of Japan, 85(9), p.094709_1 - 094709_5, 2016/09

 Times Cited Count:1 Percentile:83.83(Physics, Multidisciplinary)

Journal Articles

Observation of all-in type tetrahedral displacements in nonmagnetic pyrochlore niobates

Torigoe, Shuhei*; Ishimoto, Yutaro*; Aoishi, Yuhei*; Murakawa, Hiroshi*; Matsumura, Daiju; Yoshii, Kenji; Yoneda, Yasuhiro; Nishihata, Yasuo; Kodama, Katsuaki; Tomiyasu, Keisuke*; et al.

Physical Review B, 93(8), p.085109_1 - 085109_5, 2016/02

 Times Cited Count:4 Percentile:68.29(Materials Science, Multidisciplinary)

Journal Articles

Synthesis of heterostructured SiC and C-SiC nanotubes by ion irradiation-induced changes in crystallinity

Taguchi, Tomitsugu; Yamamoto, Shunya; Kodama, Katsuaki; Asaoka, Hidehito

Carbon, 95, p.279 - 285, 2015/12

 Times Cited Count:8 Percentile:61.92(Chemistry, Physical)

Amorphous SiC nanotubes are successfully synthesized by 340 keV Si$$^{+}$$ ions irradiation of polycrystalline SiC nanotubes for the first time. A polycrystalline/amorphous heterostructure SiC nanotube, in which polycrystalline SiC and amorphous SiC coexist in the same nanotube, is also synthesized by ions irradiation with a mask in front of polycrystalline SiC nanotube. According to electron energy loss spectroscopy evaluation, the plasmon energies of SiC nanotube change rapidly at the interface between polycrystalline and amorphous regions. The volume swelling by amorphization evaluated from the differences of plasmon energies is approximately 5.0%. This result reveals that the further relaxed amorphous SiC nanotubes with higher density can be produced. The graphitic shells in carbon layer of C-SiC nanotube gradually bend to the radial direction of nanotube by the ion irradiation. Since the graphite (002) spots in the selected area electron diffraction pattern are clearly observed even after the ion irradiation, the carbon layer in C-SiC nanotube has certain crystallinity. Moreover, the new multi-walled carbon nanotube with the graphitic shells completely parallel to the radial direction of nanotube is also produced inside the amorphous SiC tubular layer in the case of C-SiC nanotube with large caliber.

Journal Articles

Crystal structures and magnetic properties of nickel chain compounds PbM$$_2$$Ni$$_6$$Te$$_3$$O$$_{18}$$ (M = Mn, Cd)

Doi, Yoshihiro*; Suzuki, Ryo*; Hinatsu, Yukio*; Kodama, Katsuaki; Igawa, Naoki

Inorganic Chemistry, 54(22), p.10725 - 10731, 2015/11

 Times Cited Count:1 Percentile:93.54(Chemistry, Inorganic & Nuclear)

Journal Articles

Local lattice distortion caused by short-range charge ordering in transition metal oxides

Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro; Hoshikawa, Akinori*; Ishigaki, Toru*

JPS Conference Proceedings (Internet), 8, p.034002_1 - 034002_6, 2015/09

Journal Articles

Nuclear and electron density distributions of LiMn$$_{2}$$O$$_{4}$$ analyzed by combination of Rietveld/ maximum entropy method

Igawa, Naoki; Kodama, Katsuaki; Birumachi, Atsushi; Taguchi, Tomitsugu

e-Journal of Surface Science and Nanotechnology (Internet), 13, p.247 - 252, 2015/05

The nuclear and electron density distributions of LiMn$$_{2}$$O$$_{4}$$ which is one of the primitive cathode materials for secondary Li-ion batteries, were analyzed by applying Rietveld refinement and MEM to neutron and X-ray diffraction data, to estimate the Li diffusing pathway. The crystal structure of LiMn$$_{2}$$O$$_{4}$$ could be refined with the space group, ${it Fd}$-3${it m}$ in the temperature range from 240 to 573 K. The structure was transformed to ${it Fddd}$ below 240 K. The isotropic thermal displacement parameter of Li was proportional to the temperature excluding 240 to 300 K. According to the MEM analyses it was indicated that the Li ions diffuse through 8${it b}$ and 16${it e}$ around 300 K.

Journal Articles

Anisotropic magnetic form factor in a detwinned single crystal of BaFe$$_2$$As$$_2$$

Kodama, Katsuaki; Ishikado, Motoyuki*; Wakimoto, Shuichi; Kiho, Kunihiro*; Lee, C.-H.*; Iyo, Akira*; Eisaki, Hiroshi*; Shamoto, Shinichi

Physical Review B, 90(14), p.144510_1 - 144510_5, 2014/10

 Times Cited Count:1 Percentile:93.73(Materials Science, Multidisciplinary)

Journal Articles

Superconductivity in noncentrosymmetric iridium silicide Li$$_2$$IrSi$$_3$$

Pyon, S.*; Kudo, Kazutaka*; Matsumura, Junichi*; Ishii, Hiroyuki*; Matsuo, Genta*; Nohara, Minoru*; Hojo, Hajime*; Oka, Kengo*; Azuma, Masaki*; Garlea, V. O.*; et al.

Journal of the Physical Society of Japan, 83(9), p.093706_1 - 093706_5, 2014/09

 Times Cited Count:18 Percentile:22.16(Physics, Multidisciplinary)

Journal Articles

Local structural analysis by using atomic pair distribution function on mixed valence compound LiMn$$_2$$O$$_4$$

Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro; Hoshikawa, Akinori*; Ishigaki, Toru*

JPS Conference Proceedings (Internet), 3, p.013012_1 - 013012_6, 2014/06

Journal Articles

2D neutron diffraction imaging on an ammonite

Shamoto, Shinichi; Kodama, Katsuaki; Imaki, Tadashi*; Nakatani, Takeshi; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Masuko, Kenji*; Sakamoto, Kensaku; Yamaguchi, Kenji; Suzuya, Kentaro; et al.

JPS Conference Proceedings (Internet), 1, p.014011_1 - 014011_5, 2014/03

2D neutron diffraction imaging of an ammonite fossil was carried out at high-intensity total diffractometer NOVA in J-PARC. Observed diffraction profiles consist of calcite, siderite and amorphous structures.

Journal Articles

Magnetic structure and electromagnetic properties of LnCrAsO with a ZrCuSiAs-type structure (Ln = La, Ce, Pr, and Nd)

Park, S.-W.*; Mizoguchi, Hiroshi*; Kodama, Katsuaki; Shamoto, Shinichi; Otomo, Toshiya*; Matsuishi, Satoru*; Kamiya, Toshio*; Hosono, Hideo*

Inorganic Chemistry, 52(23), p.13363 - 13368, 2013/12

 Times Cited Count:15 Percentile:33.51(Chemistry, Inorganic & Nuclear)

Journal Articles

Local lattice distortion caused by short range charge ordering in LiMn$$_2$$O$$_4$$

Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro

Journal of the Physical Society of Japan, 82(9), p.094601_1 - 094601_6, 2013/09

 Times Cited Count:8 Percentile:43.37(Physics, Multidisciplinary)

Journal Articles

Introduction of structural investigations on angular dispersive neutron diffractometers

Oyama, Kenji*; Kodama, Katsuaki; Igawa, Naoki

Hamon, 23(2), p.147 - 153, 2013/05

Journal Articles

From antiferromagnetic insulator to ferromagnetic metal; Effect of hydrogen substitution in LaMnAsO

Hanna, Taku*; Matsuishi, Satoru*; Kodama, Katsuaki; Otomo, Toshiya*; Shamoto, Shinichi; Hosono, Hideo*

Physical Review B, 87(2), p.020401_1 - 020401_5, 2013/01

 Times Cited Count:26 Percentile:20.92(Materials Science, Multidisciplinary)

156 (Records 1-20 displayed on this page)