Pressure effects on superconductivity and structural parameters of ThFeAsN

¹ Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences Beijing 100190, China
² Department of Physics, Zhejiang University - Hangzhou 310027, China
³ Department of Physics, Shandong University of Technology - Zibo 255049, China
⁴ Institute of High Energy Physics, Chinese Academy of Science - Beijing 100049, China
⁵ University of Chinese Academy of Sciences - Beijing 100190, China

^(a) llsun@iphy.ac.cn (corresponding author)

Received: 12 June 2018
Accepted: 19 September 2018

Abstract

Here we report effects of pressure on the recently discovered iron-based superconductor ThFeAsN, the first FeAs-based superconductor containing an actinide element, by in situ high-pressure resistance and synchrotron X-ray diffraction measurements. Our results show that the superconducting transition temperature (T_C) decreases monotonously with increasing pressure and then vanishes at 25.4 GPa. The analysis of the As anion height above the Fe layer (), as well as the bond angle of As-Fe-As (α), for the pressurized ThFeAsN sample found that its T_C vs.  or α follows the same universal curve describing most of the iron-based superconductors. The results indicate that the lattice parameters also control the superconductivity of the ThFeAsN superconductor, similar to other FeAs-based superconductors, as long as the “superconducting gene” is a FeAs layer. Furthermore, we demonstrate that the ambient-pressure ThFeAsN is an “intrinsic” superconductor, while its lattice structure is not in the optimal state of the FeAs-based superconductors.