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Name (Title): Y.G. Shi, S. Yu, A. A. Belik, Y. Guo, Y. Matsushita,
M. Tanaka, Y. Katsuya, K. Kobayashi, Y. Hata, H. Yasuoka,
K. Yamaura and E. Takayama-Muromachi
Affiliation:
National Institute for Materials Science
Address:
1-1 Namiki, Tsukuba, Ibaraki, 305-0044 Japan
Email: SHI.Youguo@nims.go.jp
Home Page:
Presentation Title:
Superconducting properties of the oxygen-vacant iron oxyarsenide TbFeAsO1-δ
Abstract:
A wide-range doping was attained for TbFeAsO1-δ from “under doped” to “over doped”
throughout the optimized superconductivity at Tc of 42 K by controlling the oxygen vacancy
concentration, δ. A clear bell-shaped feature of Tc vs. δ was observed (see Fig. 1. (d)) similar to
the copper oxide superconductors. This similarity between the iron and the copper oxides may
imply common physics underlying their superconductivity. The smaller ionic radius of the Tb
ion compared with La, Ce, Pr, Nd, Sm ions may play a key role to expand the doping range from
the “under-doped” to the “over-doped” region. The maximum doped level chemically available
reached 0.5 electrons per f.u. under the present synthesis condition. In the presentation, we will
discuss the principal origin of the bell-shaped feature and Tc reduction in the “over-doped”
region. Since a clear “over-doped” superconductivity was observed probably for the first time in
the LnFeAsO system, continuous efforts are directed to investigate nature of the “over-doped”
superconductivity. In addition to the Tc vs. δ relation, Tc vs. lattice constant relation was
investigated and it likely follows a unique empirical curve over the whole doping range.
Fig. 1. Oxygen concentration and temperature dependence of dc magnetic susceptibility
in the magnetic field of 10 Oe of the polycrystalline TbFeAsO1-δ, where (a) δ= 0, 0.1,
(b) 0.15, (c) 0.2, and (d) 0.25. Insets show (b) the isothermal magnetization curve at 5 K
of TbFeAsO0.85, and (d) Tc vs. δ relation.
Poster Session PM-19
61