Multiband behavior and non-metallic low-temperature state of K${}_{0.50}$Na${}_{0.24}$Fe${}_{1.52}$Se${}_2$

Abstract

We report evidence for multiband transport and an insulating low-temperature normal state in superconducting K${}_{0.50}$Na${}_{0.24}$Fe${}_{1.52}$Se${}_2$ with $T_c\approx 20$ K. The temperature-dependent upper critical field, $H_{c2}$, is well described by a two-band BCS model. The normal-state resistance, accessible at low temperatures only in pulsed magnetic fields, shows an insulating logarithmic temperature dependence as $T\to 0$ after superconductivity is suppressed. This is similar as for high-$T_c$ copper oxides and granular type-I superconductors, suggesting that the superconductor-insulator transition observed in high magnetic fields is related to intrinsic nanoscale phase separation.

arXiv comment5 pages, 4 figures

References in corpus (34)

• Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors
• Imaging the granular structure of high-Tc superconductivity in underdoped Bi2Sr2CaCu2O8+x
• Spin-Gap Proximity Effect Mechanism of High Temperature Superconductivity
• Granular Electronic Systems
• Very High Field Two-Band Superconductivity in LaFeAsO_0.89F_0.11
• Nearly Isotropic superconductivity in (Ba,K)Fe2As2
• Upper critical fields and thermally-activated transport of Nd(O_0.7F_0.3)FeAs single crystal
• Observation of superconductivity at 30 K~46 K in AxFe2Se2 (A = Li, Na, Ba, Sr, Ca, Yb, and Eu)
• Phase Separation and Magnetic Order in K-doped Iron Selenide Superconductor
• Microstructure and Fe-vacancy ordering in the KFexSe2 superconducting system
• Metal-to-Insulator Crossover in the Low-Temperature Normal State of Bi_{2}Sr_{2-x}La_{x}CuO_{6+δ}
• Observation of Temperature-Induced Crossover to an Orbital-Selective Mott Phase in A${}_x$Fe${}_{2-y}$Se${}_2$ (A=K, Rb) Superconductors
• Intrinsic phase separation in superconducting K0.8Fe1.6Se2 (Tc= 31.8 K) single crystals
• Pauli-limited upper critical field in Fe1+yTe1-xSex
• Psuedo-isotropic upper critical field in cobalt-doped SrFe2As2 epitaxial films
• Phase relations in K_xFe_{2-y}Se_2 and the structure of superconducting K_xFe_2Se_2 via high-resolution synchrotron diffraction
• High-Field Pauli-Limiting Behavior and Strongly Enhanced Upper Critical Magnetic Fields near the Transition Temperature of an Arsenic-Deficient LaO_0.9F_0.1FeAs_(1-δ) Superconductor
• Upper critical fields of the 11-system iron-chalcogenide superconductor FeSe${}_{0.25}$Te${}_{0.75}$
• 57-Fe Mossbauer study of magnetic ordering in superconducting K_0.85Fe_1.83Se_2.09 single crystals
• Phase Diagram of KxFe2-ySe2-zSz and the Suppression of its Superconducting State by an Fe2-Se/S Tetrahedron Distortion
• Multiband effects on beta-FeSe single crystals
• Evolution of precipitate morphology during heat treatment and its implications for the superconductivity in KxFe1.6+ySe2 single crystals
• Anisotropic Hc2 of K0.8Fe1.76Se2 determined up to 60 T
• Effects of excess Fe on upper critical field and magnetotransport in Fe1+y(Te1-xSx)z
• Spin fluctuations and superconductivity in KxFe{2-y}Se2
• Giant increase in critical current density of KxFe2-ySe2 single crystals
• Reversibly tuning the insulating and superconducting state in KxFe2-ySe2 crystals by post-annealing
• Metastable superconducting state in quenched KxFe2-ySe2
• Local structural disorder and superconductivity in KxFe2-ySe2
• Upper critical magnetic field in K0.83Fe1.83Se2 and Eu0.5K0.5Fe2As2 single crystals
• Interplay of the electronic and lattice degrees of freedom in A_{1-x}Fe_{2-y}Se_{2} superconductors under pressure
• Upper critical fields and superconducting anisotropy of K0.70Fe1.55Se1.01S0.99 and K0.76Fe1.61Se0.96S1.04 single crystals
• Intrinsic high-temperature superconductivity in ternary iron selenides
• Effect of the Wyckoff position of K atom on the crystal structure and electronic properties of KFe${}_2$Se${}_2$ compound