Superconductivity induced by cobalt doping in iron-based oxyarsenides

Abstract

Chemical doping has recently become a very important strategy to induce superconductivity especially in complex compounds. Distinguished examples include Ba-doped La${}_2$CuO${}_4$ (the first high temperature superconductor), K-doped BaBiO${}_3$, K-doped C${}_{60}$ and Na${}_x$CoO${}_2\cdot y$H${}_2$O. The most recent example is F-doped LaFeAsO, which leads to a new class of high temperature superconductors. One notes that all the above dopants are non-magnetic, because magnetic atoms generally break superconducting Cooper pairs. In addition, the doping site was out of the (super)conducting structural unit (layer or framework). Here we report that superconductivity was realized by doping magnetic element cobalt into the (super)conducting-active Fe${}_2$As${}_2$ layers in LaFe${}_{1-x}$Co${}_x$AsO. At surprisingly small Co-doping level of $x$=0.025, the antiferromagnetic spin-density-wave transition in the parent compound is completely suppressed, and superconductivity with $T_c\sim$ 10 K emerges. With increasing Co content, $T_c$ shows a maximum of 13 K at $x\sim 0.075$, and then drops to below 2 K at $x$=0.15. This result suggests essential differences between previous cuprate superconductor and the present iron-based arsenide one.

4 pages, 4 figures

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Cited by in corpus (12)

• Substitution Effects on FeSe Superconductor
• Superconductivity up to 30 K in the vicinity of quantum critical point in BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Superconductivity induced by phosphorus doping and its coexistence with ferromagnetism in EuFe${}_2$(As${}_{0.7}$P${}_{0.3}$)${}_2$
• Psuedo-isotropic upper critical field in cobalt-doped SrFe2As2 epitaxial films
• Superconductivity in LaFeAs${}_{1-x}$P${}_x$O: effect of chemical pressures and bond covalency
• Narrow superconducting window in Ni-doped LaFeAsO
• Superconductivity induced by ruthenium substitution in an iron arsenide: investigation of SrFe2-xRuxAs2 (0 <= x <= 2)
• Evolution of bulk superconductivity in SrFe2As2 with Ni substitution
• Suppression of spin-density-wave transition and emergence of ferromagnetic ordering of Eu${}^{2+}$ moments in EuFe${}_{2-x}$Ni${}_x$As${}_2$
• Effect of Zn doping on magnetic order and superconductivity in LaFeAsO
• Comparison of crystal structures and effects of Co substitution in a new member of Fe-1111 superconductor family AeFeAsF(Ae = Ca and Sr): a possible candidate for higher Tc superconductor
• Magnetic impurities in the two-band $s_{\pm }$-wave superconductors