The discovery of EuFeAs₂, currently the only charge-neutral parent phase of the 112-type iron-pnictide system, provides a new platform for the study of elemental doping effects on magnetism and superconductivity (SC). In this study, a series of polycrystalline EuFe_1−yCo_yAs₂ and Eu_0.9Pr_0.1Fe_1−yCo_yAs₂ samples are synthesized through solid-state reaction, and the evolutions of SC and magnetism with Co doping in EuFeAs₂ and Eu_0.9Pr_0.1FeAs₂ are investigated by electrical transport and magnetic susceptibility measurements. For EuFe_1−yCo_yAs₂, the Eu-related antiferromagnetic (AFM) transition around 40 K is barely affected by Co doping, while the Fe-related spin density wave (SDW) transition temperature drops rapidly. Meanwhile, SC is induced by a trace amount of Co doping, with a highest transition temperature T_c∼28 K found in EuFe_0.9Co_0.1As₂. For the Eu_0.9Pr_0.1Fe_1−yCo_yAs₂ series, the magnetism and superconductivity show similar evolutions upon Co doping, and the highest T_c is enhanced to 30.6 K with an optimum doping level y ∼ 0.07. Our results shed light on the competition between SC and SDW with Co doping in the 112-type EuFeAs₂ system.

EuFeAs ₂的发现，目前是112型铁肽体系中唯一的电荷中性母相，为研究元素掺杂对磁性和超导性（SC）的影响提供了新的平台。本研究通过固相反应合成了一系列的多晶EuFe _{1- y} Co _y As ₂和Eu _0.9 Pr _0.1 Fe _{1- y} Co _y As ₂样品，并研究了EuFeAs中Co掺杂的SC和磁性的演化。₂和Eu _0.9 Pr _0.1 FeAs ₂通过电传输和磁化率测量进行研究。对于EuFe _{1- y} Co _y As _2而言，Co掺杂几乎不会影响40 K附近的Eu相关反铁磁（AFM）转变，而Fe相关自旋密度波（SDW）转变温度会迅速下降。另一方面，SC被钴掺杂微量的诱导，具有最高转变温度Ť _Ç ~28 K的EuFe发现_0.9钴_0.1如图₂。对于Eu _0.9 Pr _0.1 Fe _{1- y} Co _y As ₂系列，磁性和超导显示在共掺杂类似演变，而最高Ť _Ç被增强以30.6 K的最佳掺杂水平ý〜0.07。我们的研究结果揭示了112型EuFeAs ₂系统中Co掺杂对SC和SDW之间的竞争。