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      Permanent link:
      https://www.ias.ac.in/article/fulltext/jcsc/122/01/0043-0046

    • Keywords

       

      Oxypnictides; superconductivity; upper critical field.

    • Abstract

       

      The effect of ytterbium substitution at the lanthanum site on the superconducting properties of La$_{1-x}$Yb$_x$O0.8F0.2FeAs ($x = 0.10$, 0.20 and 0.30) oxypnictides has been investigated. Powder X-ray diffraction studies show the presence of Yb2O3 and LaOF as secondary phases. The superconducting transition temperature ($T_c$) of 31.3 ($\pm \, 0.05$) K has been observed in $x = 0.1$ composition which is the maximum $T_c$ so far in the La(O/F)FeAs superconductor family at ambient pressure. Further increase in 𝑥 leads to suppression and broadening of superconducting transition. The resistive transition curves under different magnetic fields were investigated, leading to determination of upper critical field $H_{c2}$ (𝑇) of this new superconductor. The value of $H_{c2}$ at zero temperature is estimated to be about 46 T corresponding to coherence length ∼ 27 Å.

    • Author Affiliations

       

      J Prakash1 S J Singh2 S Patnaik2 A K Ganguli1

      1. Department of Chemistry, Indian Institute of Technology, New Delhi 110 016
      2. School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067

    • Dates

       
      Published
      January 2010

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