Discovery of a novel 112-type iron-pnictide and La-doping induced   superconductivity in Eu1-xLaxFeAs2 (x = 0 ~ 0.15)
  We report the discovery and characterization of a novel 112-type iron pnictide EuFeAs2, with La-doping induced superconductivity in a series of Eu1-xLaxFeAs2. The polycrystalline samples were synthesized through solid state reaction method only within a very narrow temperature window around 1073 K. Small single crystals were also grown from a flux method with the size about 100 um. The crystal structure was identified by single crystal X-ray diffraction analysis as a monoclinic structure with space group of P21/m. From resistivity and magnetic susceptibility measurements, we found that the parent compound EuFeAs2 shows a Fe2+ related antiferromagnetic/structural phase transition near 110 K and a Eu2+ related antiferromagnetic phase transition near 40 K. La doping suppressed the both phase transitions and induced superconducting transition with a Tc ~ 11 K for Eu0.85La0.15FeAs2. 
Jia Yu, Tong Liu, Bo-Jin Pan, Bin-Bin Ruan, Xiao-Chuan Wang, Qing-Ge   Mu, Kang Zhao, Gen-Fu Chen, Zhi-An Ren
cond-mat.supr-con cond-mat.mtrl-sci cond-mat.str-el