Single crystal growth and superconducting properties of LiFeAs

TL;DR

This paper reports the successful growth of high-quality LiFeAs single crystals and characterizes their superconducting properties, including critical temperature, critical fields, and anisotropy, providing insights into their superconducting behavior.

Contribution

The study presents a reliable method for growing large LiFeAs single crystals and provides detailed measurements of their superconducting properties, advancing understanding of this material.

Findings

Superconducting transition temperature of 18.2 K

Upper critical fields of ~17.2 T (c-axis) and ~36.9 T (ab-plane)

Superconducting anisotropy approximately 2.3

Abstract

We report the successful growth of high quality single crystals of LiFeAs with lateral sizes up to 5 x 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 deltaCp/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 Xi_ab = 4.4 and Xi_c = 2.0 nm in a single band model. This result points to a modest superconducting anisotropy about 2.3 in LiFeAs.