A Self-Doped Oxygen-Free High-Critical-Temperature (High-T_c) Superconductor: SmFFeAs

Abstract

A new iron-base superconductor SmFFeAs is synthesized via solid-state metathesis reaction by using SmFCl and LiFeAs as precursors. The compound crystallized in the tetragonal ZrCuSiAs-type structure with the space group P4/nmm and lattice parameters of a = 3.9399(0) Å and c = 8.5034(1) Å. The superconducting diamagnetic transition occurs at 56 K for the parent compound, which confirmed by the resistivity and magnetic susceptibility. The appearance of superconductivity without extrinsic doping could be ascribed to the self-doping owing to the mixed valence of Sm ions. The as-synthesized SmFFeAs serves as a new self-doped parent compound for oxygen-free high-critical-temperature (high-T c) superconductors.

Synthesis, crystal structure and physical properties of ThV2Si2C containing V2C square lattices

“…On one hand, it suggests the possibility of an intrinsic weak superconducting state, akin to those observed in systems LaO 1− x F x BiS 2 , 37 A x Fe 2 Se 2 , 38 BaFe 2 Se 3 39,40 and SmFFeAs. 41 On the other hand, the emergence of superconductivity could potentially stem from the existence of trace amounts of ThSi 2 (with a T c of 2.41 K) 42 within the sample, despite the impurity's T c being slightly higher than our observed transition temperature. Therefore, it is necessary to prepare high-quality single crystal samples and high pressure experiments to clarify the superconductivity of ThV 2 Si 2 C.…”