Single-crystal growth and superconducting properties of LiFeAs
CeNSCMR & Department of Physics and Astronomy, Seoul National University - Seoul 151-747, Republic of Korea
2 Department of Physics, University of Florida - Gainesville, FL 32611-8440, USA
Accepted: 10 September 2010
We report the successful growth of high-quality single crystals of LiFeAs with lateral sizes up to 5×5 mm2 by the Sn-flux method. Electrical resistivity studies reveal that the superconducting onset temperature is 18.2 K with a transition width less than 1.1 K and the ratio of room temperature to residual resistivity is about 24. Bulk superconductivity is supported by perfect shielding in the magnetic susceptibility and a clear jump in the specific heat Cp, resulting in ΔCp/T ≈ 20.0 mJ/mol K2. Upper-critical-field slopes of dHc2c/dT ≈−1.39 and dHc2ab/dT ≈−2.99 T/K near Tc predict zero-temperature upper critical fields of Hc2c(0) ≈ 17.2 and Hc2ab(0) ≈ 36.9 T and coherence lengths of ξab=4.4 and ξc=2.0 nm in a single-band model. This result points to a modest superconducting anisotropy about 2.3 in LiFeAs.
PACS: 74.70.Xa – Pnictides and chalcogenides / 74.25.F- – Transport properties / 74.25.-q – Properties of superconductors
© EPLA, 2010