Awana, V. P. S and Pal , Anand and Husain, M. and Kishan, H. (2010) Appearance and Disappearance of Superconductivity with Fe Site Co Substitution in SmFe1−x Cox AsO (x = 0.0 to 1.0). Journal of Superconductivity and Novel Magnetism, 24 (1-2). pp. 151-157. ISSN 1557-1947

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We report synthesis, structural details, and magnetization of SmFe1−x Co x AsO with x ranging from 0.0 to 1.0 at a close interval of 0.10. It is found that Co substitutes fully at the Fe site in SmFeAsO in an iso-structural lattice with a slightly compressed cell. The parent compound exhibited known spin density wave (SDW) character below 150 K. Successive doping of Co at the Fe site suppressed the SDW transition for x=0.05, and later induced superconductivity for x=0.10, 0.15, and 0.20, respectively, at 14, 15.5, and 9 K. The appearance of bulk superconductivity is established by wide open isothermal magnetization M(H) loops. For higher content of Co, i.e. x≥0.30, superconductivity is not observed. Clearly, the Co substitution at the Fe site in SmFe1−x Co x AsO diminishes the Fe SDW character (x=0.05), introduces bulk superconductivity for x from 0.10 to 0.20, and finally becomes a non-superconductor. The SmCoAsO also exhibits a secondary AFM-like transition below or around 50 K. The reported AFM ordering of Sm spins is seen from heat capacity C p(T) at 4.5 K and the same remains invariant with Co doping in SmFe1−x Co x AsO. Further, the FM ordering of Co-spins (seen in magnetization measurements) is not evident in C p(T) studies, suggesting weak correlations between ordered Co-spins in these systems.

Item Type: Article
Additional Information: Copyright for this article belongs to M/s Springer Verlag.
Uncontrolled Keywords: Oxy-pnictides superconductivity; SmFe1-xCoxAsO; X-ray diffraction; Structural analysis; Magnetization and heat capacity
Subjects: Applied Physics/Condensed Matter
Depositing User: Mr. Abhishek Yadav
Date Deposited: 05 Nov 2012 07:22
Last Modified: 05 Nov 2012 07:22

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