Superconductivity at 22 K in Ir-doped CaFe2−xIrxAs2 single crystals
Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences - P. O. Box 2703, Beijing 100190, China
Accepted: 5 October 2011
In this paper we report superconductivity in single crystals of the new iron-pnictide system CaFe2−xIrxAs2 (x=0, 0.05, 0.10, 0.13) grown by a self-flux solution method and characterized via X-ray, transport and magnetic measurements. The magnetic ordering associated with a structural transition at 160 K present in CaFe2As2 is completely suppressed by substitution of Fe with Ir and superconductivity is induced at a critical temperature Tc=22 K in the sample with x=0.13. We also determined the upper critical fields along the ab-plane and c-axis. The anisotropy of the CaFe2−xIrxAs2 superconductors determined by the ratio of Habc2 and Hcc2 is estimated to be 1.5–2.2. Our results suggest that superconductivity can also be easily induced in the CaFe2As2 family by substituting the Fe with Ir, at almost the similar maximum transition temperatures as for Co, Ni and Rh doping.
PACS: 74.25.-q – Properties of superconductors / 74.25.F- – Transport properties / 74.70.Xa – Pnictides and chalcogenides
© EPLA, 2011