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Shamoto, Shinichi; Wakimoto, Shuichi; Kodama, Katsuaki; Ishikado, Motoyuki; Christianson, A. D.*; Lumsden, M. D.*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Arai, Masatoshi; et al.
Physica C, 471(21-22), p.639 - 642, 2011/11
Times Cited Count：0 Percentile：0(Physics, Applied)We have studied low-energy spin excitations on polycrystalline LaFeAsO
F
samples by inelastic neutron scattering. The dynamical spin susceptibility 
''(
) of the superconducting samples is found to be comparable to that of the magnetically ordered parent sample. On the other hand, ''() almost vanishes at x=0.158, where the superconducting transition temperature T
is suppressed to 7 K. This suggests that the low energy spin excitations are closely connected with high-T superconductivity. The disappearance of the spin excitations at low energy would correspond to the disappearance of the hole Fermi surface as the electron concentration increases with doping, as observed in ARPES measurements of BaFe
CoAs
at x=0.15. The relationship between the spin excitation and the Fermi surface will be discussed in comparison with other iron-based superconductors.
Matsuda, Iwao*; Nakamura, Fumitaka*; Kubo, Keisuke*; Hirahara, Toru*; Yamazaki, Shiro*; Choi, W. H.*; Yeom, H. W.*; Narita, Hisashi*; Fukaya, Yuki; Hashimoto, Mie*; et al.
Physical Review B, 82(16), p.165330_1 - 165330_6, 2010/10
Times Cited Count：9 Percentile：40.66(Materials Science, Multidisciplinary)no abstracts in English
Ono, Masao; Iguchi, Yusuke*; Okayasu, Satoru; Esaka, Fumitaka; Kobayashi, Katsura*; Hao, T.; Bagum, R.*; Osawa, Takahito; Fujii, Kimio; Nakamura, Eizo*; et al.
Defect and Diffusion Forum, 289-292, p.63 - 68, 2009/04
The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 0.81
10
G for 100 hours at 150 
C in solid state in our previous study. The isotope ratio measurements were performed on the centrifuged sample with secondary ion mass spectrometer (SIMS). 
Pb/
Pb and 
Pb/Pb isotope ratio changed with negative gradient in the direction of centrifugal force approximately 1.5% and 0.8%, respectively. And three-isotope diagram of Pb/Pb versus Pb/Pb proved that the isotope fluctuation depends on isotopic mass difference. These results showed that the strong gravitational field not only affected on the inter-diffusion but also on self-diffusion in this alloy as causing isotope fractionation effect, and the isotope fractionation was dependent on mass-difference.
Ono, Masao; Iguchi, Yusuke*; Okayasu, Satoru; Esaka, Fumitaka; Kobayashi, Katsura*; Hao, T.; Bagum, R.*; Osawa, Takahito; Fujii, Kimio; Nakamura, Eizo*; et al.
Journal of Nuclear Science and Technology, 45(Suppl.6), p.108 - 110, 2008/09
Times Cited Count：1 Percentile：10.05(Nuclear Science & Technology)The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 810,000 G for 100 hours at 150C (solid state) in our previous study. The isotope fluctuation on this sample was measured using secondary ion mass spectrometer (SIMS). The ratio both Pb/Pb and 
In/
In changed with positive gradient in the direction of centrifugal force approximately 1.2%. These isotope fluctuations were larger than that of starting state of natural state (In
0.2%, Pb0.1%). These show that the sedimentation of isotopes occurred by solid centrifugation in this alloy, although achieved concentration gradients were small.
Ono, Masao; Iguchi, Yusuke*; Okayasu, Satoru; Esaka, Fumitaka; Kobayashi, Katsura*; Hao, T.; Bagum, R.*; Osawa, Takahito; Fujii, Kimio; Nakamura, Eizo*; et al.
no journal, ,
The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 0.8110G for 100 hours at 150 C in solid state in our previous study. The isotope ratio measurements were performed on the centrifuged sample with secondary ion mass spectrometer (SIMS, CAMECA IMS-6f). Both In/In and Pb/ isotope ratio changed with negative gradient in the direction of centrifugal force approximately 1.2% showing the tendency that the heavy In isotope (Pb isotope) abundance increased and light In isotope (Pb isotope) abundance decreased in the direction of centrifugal force. This showed that the isotope fractionation effect due to sedimentation of atoms occurred in this alloy by ultracentrifuge experiment.
F systemShamoto, Shinichi; Wakimoto, Shuichi; Ishikado, Motoyuki; Kodama, Katsuaki; Esaka, Fumitaka; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Arai, Masatoshi; Christianson, A. D.*; et al.
no journal, ,
no abstracts in English
