Discovery of a novel 112-type iron-pnictide and La-doping induced superconductivity in EuLaFeAs (x=0-0.15).

We report the discovery and characterization of a novel 112-type iron pnictide EuFeAs, with La-doping induced superconductivity in a series of EuLaFeAs. The polycrystalline samples were synthesized through solid state reaction method only within a very narrow temperature window around 1073K. Small single crystals were also grown from a flux method with the size about 100μm. The crystal structure was identified by single crystal X-ray diffraction analysis as a monoclinic structure with space group of P2/m. From resistivity and magnetic susceptibility measurements, we found that the parent compound EuFeAs shows distinct anomalies probably due to the Fe related antiferromagnetic/structural phase transition near 110K and the Eu related antiferromagnetic phase transition near 40K. La-doping suppressed both phase transitions to lower temperatures and induced superconducting transitions with a T∼11K for EuLaFeAs.