Superconductivity at 33 - 37 K in $AL{n}_2$Fe${}_4$As${}_4$O${}_2$ ($A$ = K and Cs; $Ln$ = Lanthanides)

Abstract

We have synthesized 10 new iron oxyarsenides, K$L{n}_2$Fe${}_4$As${}_4$O${}_2$ ($Ln$ = Gd, Tb, Dy, and Ho) and Cs$L{n}_2$Fe${}_4$As${}_4$O${}_2$ ($Ln$ = Nd, Sm, Gd, Tb, Dy, and Ho), with the aid of lattice-match [between $A$Fe${}_2$As${}_2$ ($A$ = K and Cs) and $Ln$FeAsO] approach. The resultant compounds possess hole-doped conducting double FeAs layers, [$A$Fe${}_4$As${}_4$]${}^{2-}$, that are separated by the insulating [$L{n}_2$O${}_2$]${}^{2+}$ slabs. Measurements of electrical resistivity and dc magnetic susceptibility demonstrate bulk superconductivity at $T_{\mathrm{c}}$ = 33 - 37 K. We find that $T_{\mathrm{c}}$ correlates with the axis ratio $c/a$ for all 12442-type superconductors discovered. Also, $T_{\mathrm{c}}$ tends to increase with the lattice mismatch, implying a role of lattice instability for the enhancement of superconductivity.

arXiv comment8 pages, 6 figures, 2 tables

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Cited by in corpus (15)

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• Observation of Two-dimensional Superconductivity in an Ultrathin Iron-Arsenic Superconductor
• Charge-stripe Fluctuations in Nd${}_4$Ni${}_3$O${}_8$ as Evidenced by Optical Spectroscopy
• Spectroscopic studies of the superconducting gap in the 12442 family of iron-based compounds
• Anomalous metallic oxygen band in the potential superconductor KCa${}_2$Fe${}_4$As${}_4$O${}_2$
• Quasi-two-dimensional heterostructures (K$M_{1-x}$Te)(LaTe${}_3$) ($M$ = Mn, Zn) with charge density waves
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• Synthesis, structure and properties of layered phosphide nitrides $Ak$Th${}_2$Mn${}_4$P${}_4$N${}_2$ ($Ak$ = Rb, Cs)
• Structural design and multiple magnetic orderings of the intergrowth compound Eu${}_2$CuMn${}_2$P${}_3$