Discovery and physical properties of new iron-based superconductors (Ca,\textit{RE})FeAs$_{2}$

POSTER

Abstract

Since 2008, iron-based superconductors with various blocking layers have been reported. However, discovery of new superconductors has been still expected. Here, we report a new superconductor (Ca,\textit{RE})FeAs$_{2}$ [(Ca,\textit{RE})112]. Plate-like single crystals of the new compound were successfully grown, and single crystal X-ray diffraction analysis revealed the monoclinic crystal structure of the new phase. The structure is composed of two Ca(Pr) planes, anti-fluorite type Fe$_{2}$As$_{2}$ layer, and As$_{2}$ zigzag chain layer. HAADF-STEM images of the sample correspond well to the structure determined by the XRD analysis. Large diamagnetism suggesting 20 K-class bulk superconductivity was observed in magnetization measurement, and superconducting transition accompanying zero resistance was also confirmed in resistivity measurement. We have also succeeded in the syntheses of (Ca,\textit{RE})112 phase with \textit{RE} $=$ La, Ce, Nd, and Sm. (Ca,La)112 phase showed higher $T_{\mathrm{c}}$ than (Ca,Pr)112 phase.

Authors

  • Hiroyuki Yakita

    • The University of Tokyo

  • Hiraku Ogino

    • The University of Tokyo

  • Alberto Sala

    • The University of Tokyo

  • Tomoyuki Okada

    • The University of Tokyo

  • Akiyasu Yamamoto

    • The University of Tokyo

  • Kohji Kishio

    • The University of Tokyo

  • Tetsuya Tohei

    • The University of Tokyo

  • Yuichi Ikuhara

    • The University of Tokyo

  • Jun-ichi Shimoyama

    • The University of Tokyo

  • Yoshito Gotoh

    • National Institute of Advanced Industrial Science and Technology

  • Hiroshi Fujihisa

    • National Institute of Advanced Industrial Science and Technology

  • Kunimitsu Kataoka

    • National Institute of Advanced Industrial Science and Technology

  • Hiroshi Eisaki

    • National Institute of Advanced Industrial Science and Technology