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.

Pressure induced Lifshitz transition in ThFeAsN

“…Structural parameters like anion height and As-Fe-As bond angle play an important role in superconductivity of Fe-based superconductors [25,50]. Our calculated pressure dependencies of these structural parameters are consistent with the experiments [43]. Vari- ations of anion height and As-Fe-As bond angle with external pressure follow the experimental trends only qualitatively.…”

“…Wang et al, show that the superconducting transition temperature gradually decreases with the increase of external pressure and eventually superconductivity disappears at about 25.4 GPa of hydrostatic pressure. This work also established that the universal trends of superconducting T c and anion height/α are followed by ThFeAsN system [25,43]. However electronic structure at high pressure and its implications on superconductivity are still missing in the current literature.…”

“…The unit cell consists of two formula units (f.u.). Experimental lattice parameters of tetragonal ThFeAsN (a = 4.0305 Å, c = 8.5169 Å), are used as the input of our first principles density functional theory calculations [43]. Experimentally no long range magnetic order has been observed in ThFeAsN system.…”

“…Although a weak structural disorder at around 160 K is observed in ThFeAsN [42]. The effect of pressure in the superconducting properties of ThFeAsN has also been studied experimentally [43,44]. Wang et al, show that the superconducting transition temperature gradually decreases with the increase of external pressure and eventually superconductivity disappears at about 25.4 GPa of hydrostatic pressure.…”

Observation of spin-glass like behavior in the layered oxyselenides La2O3(Mn1−xCox)2Se2

“…The superconductivity with T C ¼ 26 K was discovered when F was doped in the O site, 3 which set off a new upsurge of the study of Fe-based superconductivity in LnOFeAs. [4][5][6][7][8] Recently, a new layered compound ThFeAsN, which is crystallized with arsenide layer [Fe 2 As 2 ] and nitride layer [Th 2 N 2 ], was synthesized and show superconductivity below 30 K. 9,10 Additionally, another family of the 1111-type layered compound ACuS (A ¼ LaO, SrF, and BaF) crystallizes with sulde layer [Cu 2 S 2 ] and oxide or uoride A layer. [11][12][13][14] The analog BiCuSeO have attracted much attention in thermoelectric eld.…”