Superconductivity at 33 - 37 K in ALn₂Fe₄As₄O₂ (A = K and Cs; Ln = Lanthanides)

2017/04/05 by Si-Qi Wu, Zhi-Cheng Wang, Chao-Yang He +3 · 1 citation
Physics and Astronomy · #cond-mat.supr-con #cond-mat.mtrl-sci

paper · pdf · doi:10.1103/physrevmaterials.1.044804

published as Phys. Rev. Materials 1, 044804 (2017) · 8 pages, 6 figures, 2 tables

arxiv created 2017/04/05 · arxiv updated 2017/09/13

Abstract

We have synthesized 10 new iron oxyarsenides, KLn₂Fe₄As₄O₂ (Ln = Gd, Tb, Dy, and Ho) and CsLn₂Fe₄As₄O₂ (Ln = Nd, Sm, Gd, Tb, Dy, and Ho), with the aid of lattice-match [between AFe₂As₂ (A = K and Cs) and LnFeAsO] approach. The resultant compounds possess hole-doped conducting double FeAs layers, [AFe₄As₄]^2-, that are separated by the insulating [Ln₂O₂]²⁺ slabs. Measurements of electrical resistivity and dc magnetic susceptibility demonstrate bulk superconductivity at T_c = 33 - 37 K. We find that T_c correlates with the axis ratio c/a for all 12442-type superconductors discovered. Also, T_c tends to increase with the lattice mismatch, implying a role of lattice instability for the enhancement of superconductivity.

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