Superconductivity in KCa<sub>2</sub>Fe<sub>4</sub>As<sub>4</sub>F<sub>2</sub> with Separate Double Fe<sub>2</sub>As<sub>2</sub> Layers
journal contribution
posted on 2016-06-20, 00:00 authored by Zhi-Cheng Wang, Chao-Yang He, Si-Qi Wu, Zhang-Tu Tang, Yi Liu, Abduweli Ablimit, Chun-Mu Feng, Guang-Han CaoWe
report the synthesis, crystal structure, and physical properties
of a quinary iron arsenide fluoride, KCa<sub>2</sub>Fe<sub>4</sub>As<sub>4</sub>F<sub>2</sub>. The new compound crystallizes in a body-centered
tetragonal lattice (space group <i>I</i>4/<i>mmm</i>, <i>a</i> = 3.8684(2) Å, <i>c</i> = 31.007(1)
Å, <i>Z</i> = 2) that contains double Fe<sub>2</sub>As<sub>2</sub> conducting layers separated by insulating Ca<sub>2</sub>F<sub>2</sub> layers. Our measurements of electrical resistivity,
direct-current magnetic susceptibility, and heat capacity demonstrate
bulk superconductivity at 33 K in KCa<sub>2</sub>Fe<sub>4</sub>As<sub>4</sub>F<sub>2</sub>.
