Specific heat and angle-resolved photoemission spectroscopy study of the superconducting gaps in LiFeAs

Abstract

We present specific-heat, ${c}_{p}$, and angle-resolved photoemission spectroscopy (ARPES) data on single crystals of the stoichiometric superconductor LiFeAs. A pronounced anomaly is found in ${c}_{p}$ at the superconducting transition. The electronic contribution can be described by two $s$-type energy gaps with magnitudes of approximately ${\ensuremath{\Delta}}_{1}=1.2$ meV and ${\ensuremath{\Delta}}_{2}=2.6$ meV and a normal-state $\ensuremath{\gamma}$ coefficient of 10 mJ/mol ${\mathrm{K}}^{2}$. All these values are in agreement with ARPES results.