TITLE

Influence of Ce Substitution at Sr-Site on Superconducting Fluctuation Behavior and Infrared Absorption of TlBiSrCeCaYCuFeO ( x=0-0.20) Ceramics

AUTHOR(S)
Ismail, S.; Yahya, A.; Khan, Nawazish
PUB. DATE
August 2012
SOURCE
Journal of Superconductivity & Novel Magnetism;Aug2012, Vol. 25 Issue 6, p1849
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Ce substituted TlBiSrCeCaYCuFeO ( x=0-0.20) samples were synthesized to determine the effects of the higher valence ion substitution on superconductivity and structure of the Fe-doped Tl1212 derivatives. The normal state behavior for x=0 showed semiconductor-like behavior which gradually turned to metallic behavior with increasing Ce at x=0.05-0.15. However, further substitution of Ce for x>0.15 turned the normal state to insulating behavior. The zero critical temperature, T increased from 65.4 K ( x=0.05) to 71.0 K ( x=0.10), but slightly decreased for x>0.10 indicating the optimum value of average copper valence was achieved at x=0.10. Excess conductivity analysis using the Aslamazov Larkin, AL and Lawrence-Doniach, LD models revealed two-dimensional, 2D to three-dimensional, 3D transition of superconducting fluctuation behavior, SFB with the highest transition temperature, $T_{\mathrm{2D}\mbox{-}\mathrm{3D}}$ at x=0.10. FTIR analysis in conjunction with XRD results showed softening of FeO/CuO planar oxygen mode from 610.5 cm( x=0) to 605 cm( x=0.20) which is suggested to be related to possible increase of inter plane coupling, J and this is supported by computed results based on the LD model. The enhanced J increases superconducting coherence length along c-axis, ξ(0), and hence lowers anisotropy, γ resulting in enhanced superconducting properties.
ACCESSION #
77440185

 

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