Superconductivity and phase diagram in Ru-doped SrFe2−xRuxAs2 single crystals
Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences P. O. Box 2703, Beijing 100190, China
Accepted: 22 November 2011
Single crystals of SrFe2−xRuxAs2 have been successfully synthesized using the FeAs self-flux method. The X-ray diffraction patterns indicate that the substitution of Fe by Ru leads to a decrease of the c parameter. Upon Ru substitution, the resistivity anomaly in the parent compound is progressively suppressed and superconductivity is stabilized at low temperatures for x≥0.45. The superconducting region is dome-like, with an optimal Tc ∼15.5 K found around x=0.667. A phase diagram of temperature vs. doping, based on electrical transport, has been constructed. Results of upper and lower critical field are presented. Our results confirm that the substitution of Fe ions with isoelectronic Ru could suppress the magnetic/structural phase transition in the parent compound, and suggest that there is strong competition between magnetism, structure, and superconductivity in iron-based superconductors.
PACS: 74.70.Dd – Ternary, quaternary, and multinary compounds (including Chevrel phases, borocarbides, etc.) / 74.25.Dw – Superconductivity phase diagrams / 75.30.Fv – Spin-density waves
© EPLA, 2012