Pressure effects on superconductivity and structural parameters of ThFeAsN

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 (TC) 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 TC 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.