Crystal structure and superconductivity at about 30 K in ACa2Fe4As4F2 (A = Rb, Cs)

• DOI: 10.1007/s40843-016-5150-x
• Publication Date: 2016-12-27T00:05:13Z
• Authors: Zhicheng Wang; Chaoyang He; Zhangtu Tang; Siqi Wu; Guanghan Cao
• Keywords: Quinary; Tetragonal crystal system

We have synthesized two iron fluo-arsenides $A$Ca$_2$Fe$_4$As$_4$F$_2$ with $A$ = Rb and Cs, analogous to the newly discovered superconductor KCa$_2$Fe$_4$As$_4$F$_2$. The quinary inorganic compounds crystallize in a body-centered tetragonal lattice with space group I4/mmm, which contain double Fe$_2$As$_2$ layers that are separated by insulating Ca$_2$F$_2$ layers. Our electrical and magnetic measurements on the polycrystalline samples demonstrate that the new materials undergo superconducting transitions at Tc = 30.5 K and 28.2 K, respectively, without extrinsic doping. The correlations between Tc and structural parameters are discussed.<br/>9 pages,4 figures, 1 table<br/>