Growth and characterization of CaFe${}_{1-x}$Co${}_x$AsF single crystals by CaAs flux method

Abstract

Millimeter sized single crystals of CaFe${}_{1-x}$Co${}_x$AsF were grown using a self-flux method. It is found that high-quality single crystals can be grown from three approaches with different initial raw materials. The chemical compositions and crystal structure were characterized carefully. The c-axis lattice constant is suppressed by the Co substitution. Superconductivity with the critical transition $T_c$ as high as 21 K was confirmed by both the resistivity and magnetic susceptibility measurements in the sample with $x$ = 0.12. Moreover, it is found that $T_c$ can be enhanced for about 1 K under the very small hydrostatic pressure of 0.22 GPa, which is more quickly than that reported in the polycrystalline samples. Our results is a promotion for the physical investigations of 1111 phase iron-pnictide superconductors.

arXiv comment11 pages, 4 figures, submitted to Journal of Crystal Growth

References in corpus (8)

• Single crystals of LnFeAsO1-xFx (Ln=La, Pr, Nd, Sm, Gd) and Ba1-xRbxFe2As2: growth, structure and superconducting properties
• High-T_c superconductivity induced by doping rare earth elements into CaFeAsF
• Synthesis, crystal structure and spin-density-wave anomaly of the iron arsenide-fluoride SrFeAsF
• Flux growth at ambient pressure of millimeter-sized single crystals of LaFeAsO, LaFeAsO1-xFx, and LaFe1-xCoxAsO
• SrFeAsF as a parent compound for iron pnictide superconductors
• High-pressure flux growth, structural, and superconducting properties of LnFeAsO (Ln = Pr, Nd, Sm) single crystals
• Superconductivity in Fluorine-Arsenide Sr_{1-x}La_xFeAsF
• Effect of 3d Transition Metal Doping on the Superconductivity in Quaternary Fluoroarsenide CaFeAsF

Cited by in corpus (7)

• Strong Pauli paramagnetic effect in the upper critical field of KCa${}_2$Fe${}_4$As${}_4$F${}_2$
• Fermi surface with Dirac fermions in CaFeAsF determined via quantum oscillation measurements
• Strong anisotropy effect in iron-based superconductor CaFe${}_{0.882}$Co${}_{0.118}$AsF
• Two-Gap Superconductivity in CaFe_{0.88}Co_{0.12}AsF Revealed by Temperature Dependence of the Lower Critical Field H_{c1}^c(T)
• Large CaFeAsF single crystals of high quality grown by the oscillating temperature technique
• Multiple gaps revealed by low temperature specific heat in the 1111-type CaFe_{0.88}Co_{0.12}AsF single crystals
• Superconductivity above 30 K due to the introduction of oxygen in CaFeAsF