Nearly Isotropic superconductivity in (Ba,K)Fe2As2

Abstract

Superconductivity was recently observed in the iron-arsenic-based compounds with a superconducting transition temperature (Tc) as high as 56K [1-7], naturally raising comparisons with the high Tc copper oxides. The copper oxides have layered crystal structures with quasi-two-dimensional electronic properties, which led to speculations that reduced dimensionality (that is, extreme anisotropy) is a necessary prerequisite for superconductivity at temperatures above 40 K [8,9]. Early work on the iron-arsenic compounds seemed to support this view [7,10]. Here we report measurements of the electrical resistivity in single crystals of (Ba,K)Fe2As2 in a magnetic field up to 60 T. We find that the superconducting properties are in fact quite isotropic, being rather independent of the direction of the applied magnetic fields at low temperature. Such behaviour is strikingly different from all previously-known layered superconductors [9,11], and indicates that reduced dimensionality in these compounds is not a prerequisite for high-temperature superconductivity. We suggest that this situation arises because of the underlying electronic structure of the iron-arsenide compounds, which appears to be much more three dimensional than that of the copper oxides. Extrapolations of low-field single-crystal data incorrectly suggest a high anisotropy and a greatly exaggerated zero-temperature upper critical field.

To appear in Nature

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Cited by in corpus (19)

• To What Extent Iron-Pnictide New Superconductors Have Been Clarified: A Progress Report
• Small anisotropy, weak thermal fluctuations, and high field superconductivity in Co-doped iron pnictide Ba(Fe1-xCox)2As2
• Anisotropy of the Optimally-Doped Iron Pnictide Superconductor Ba(Fe0.926Co0.074)2As2
• Superconductivity coexisting with phase-separated static magnetic order in (Ba,K)Fe${}_2$As${}_2$, (Sr,Na)Fe${}_2$As${}_2$ and CaFe${}_2$As${}_2$
• Psuedo-isotropic upper critical field in cobalt-doped SrFe2As2 epitaxial films
• Quasiparticle Heat Transport in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$: Evidence for a k-dependent Superconducting Gap without Nodes
• Superconductivity in LaFeAs${}_{1-x}$P${}_x$O: effect of chemical pressures and bond covalency
• Competition of magnetism and superconductivity in underdoped (Ba1-xKx)Fe2As2
• Effects of the magnetic orderings on the dynamical conductivity: optical investigations of EuFe${}_2$As${}_2$ single crystals
• Resistivity and upper critical field in KFe${}_2$As${}_2$ single crystals
• Fermi surface of SrFe${}_2$P${}_2$ determined by de Haas-van Alphen effect
• Superconductivity at 23 K and Low Anisotropy in Rb-Substituted BaFe_2As_2 Single Crystals
• Effect of Zn doping on magnetic order and superconductivity in LaFeAsO
• Superconducting fluctuations in the reversible magnetization of the iron-pnictide $B{a}_{1-x}{K}_{x}F{e}_{2}A{s}_2$
• Quantum Oscillation Studies of the Fermi Surface of LaFePO
• Evidence for Coexistence of Superconductivity and Magnetism in Single Crystals of Co-doped SrFe${}_2$As${}_2$
• Conventional Superconductivity in Fe-Based Pnictides: the Relevance of Intra-Band Electron-Boson Scattering
• A first principles study on FeAs single layers
• Elastic theory for the vortex-lattice melting in iron-based high-Tc superconductors