Synthesis and Characterization of CaAFe4As4 (A = K, Rb, Cs) Superconductors

Polycrystalline samples of stoichiometric iron-based superconductors with CaKFe4As4, CaRbFe4As4, and CaCsFe4As4 compositions are synthesized by the mechanical alloying method, with their phase composition confirmed by X-ray diffraction analysis. The superconducting transition temperatures are found to be T_C^onset ≈ 34.7, 35.2, and 31.3 К for CaKFe4As4, CaRbFe4As4, and CaCsFe4As4, respectively, with the transition widths being ΔTC ≈ 7.6, 6.4, and 6.3 K. According to magnetic measurements and X-ray diffraction analysis, no impurity phases are detected in the CaKFe4As4 and CaRbFe4As4 sample.