Fully Gapped Superconducting State Based on a High Normal State Quasiparticle Density of States in Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ Single Crystals

Abstract

We report the specific heat (SH) measurements on single crystals of hole doped $FeAs$-based superconductor $B{a}_{0.6}{K}_{0.4}F{e}_{2}A{s}_2$. It is found that the electronic SH coefficient ${\gamma }_e(T)$ is not temperature dependent and increases almost linearly with the magnetic field in low temperature region. These point to a fully gapped superconducting state. Surprisingly the sharp SH anomaly $\Delta C/T{|}_{T_c}$ reaches a value of 98 $mJ/mol{K}^2$ suggesting a very high normal state quasiparticle density of states (${\gamma }_n\approx 63mJ/mol{K}^2$). A detailed analysis reveals that the ${\gamma }_e(T)$ cannot be fitted with a single gap of s-wave symmetry due to the presence of a hump in the middle temperature region. However, our data indicate that the dominant part of the superconducting condensate is induced by an s-wave gap with the magnitude of about 6 meV.

5 pages, 5 figures

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Cited by in corpus (7)

• Quasiparticle Heat Transport in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$: Evidence for a k-dependent Superconducting Gap without Nodes
• Non-exponential London penetration depth in Ba${}_{1-}$K${}_x$Fe${}_2$As${}_2$ single crystals
• Superconductivity induced by ruthenium substitution in an iron arsenide: investigation of SrFe2-xRuxAs2 (0 <= x <= 2)
• Evolution of bulk superconductivity in SrFe2As2 with Ni substitution
• Superconducting fluctuations in the reversible magnetization of the iron-pnictide $B{a}_{1-x}{K}_{x}F{e}_{2}A{s}_2$
• Vortex state in iron-based superconductors with collinear antiferromagnetic cores
• Disorder-sensitive superconductivity in the iron silicide Lu${}_2$Fe${}_3$Si${}_5$ studied by the Lu-site substitutions