Superconducting properties of K${}_{1-x}$Na${}_x$Fe${}_2$As${}_2$ under pressure

Abstract

The effect of hydrostatic pressure and partial Na substitution on the normal-state properties and the superconducting transition temperature ($T_c$) of K${}_{1-x}$Na${}_x$Fe${}_2$As${}_2$ single crystals were investigated. It was found that a partial Na substitution leads to a deviation from the standard $T^2$ Fermi-liquid behavior in the temperature dependence of the normal-state resistivity. It was demonstrated that non-Fermi liquid like behavior of the resistivity for K${}_{1-x}$Na${}_x$Fe${}_2$As${}_2$ and some KFe${}_2$As${}_2$ samples can be explained by disorder effect in the multiband system with rather different quasiparticle effective masses. Concerning the superconducting state our data support the presence of a shallow minimum around 2 GPa in the pressure dependence of $T_c$ for stoichiometric KFe${}_2$As${}_2$. The analysis of $T_c$ in the K${}_{1-x}$Na${}_x$Fe${}_2$As${}_2$ at pressures below 1.5 GPa showed, that the reduction of $T_c$ with Na substitution follows the Abrikosov-Gor'kov law with the critical temperature $T_{c0}$ of the clean system (without pair-breaking) which linearly depends on the pressure. Our observations, also, suggest that $T_c$ of K${}_{1-x}$Na${}_x$Fe${}_2$As${}_2$ is nearly independent of the lattice compression produced by the Na substitution. Further, we theoretically analyzed the behavior of the band structure under pressure within the generalized gradient approximation (GGA). A qualitative agreement between the calculated and the recently in de Haas-van Alphen experiments [T. Terashima et al., Phys.Rev.B89, 134520(2014)] measured pressure dependencies of the Fermi-surface cross-sections has been found. These calculations, also, indicate that the observed minimum around 2~GPa in the pressure dependence of $T_c$ may occur without a change of the pairing symmetry.

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Cited by in corpus (5)

• Universal V-shaped temperature-pressure phase diagram in the iron-based superconductors KFe2As2, RbFe2As2, and CsFe2As2
• Structural, electronic, and dynamical properties of the tetragonal and collapsed tetragonal phases of KFe${}_2$As${}_2$
• Quasiparticle interference in multiband superconductors with strong coupling
• Superconductivity In K- And Na- Doped Bafe2as2: What Can We Learn From Heat Capacity And Pressure Dependence of Tc
• Pressure-induced magnetism in iron-based superconductors $A$Fe${}_2$As${}_2$ ($A=$ K, Cs, Rb)