Multiband thermal transport in the iron-based superconductor Ba1 xKxFe2As2

Abstract

We present results of precise measurements of the thermal and electrical transport in the optimally- and over-doped Ba1-xKxFe2As2 single crystals (x = 0.35, 0.55, 0.88) and compare them to the previously reported data on Ba(Fe1-yCoy)2As2. A contraction of the electron pocket is observed upon substitution potassium for barium, but even at the extreme doping (x = 0.88) there is still a noticeable contribution from negative charge carriers to the electronic transport. The size of the electron pocket in all K-doped samples is small enough to cause a significant enhancement of the respective Hall-Lorenz number. Another observed characteristic is the emergence of a maximum in the transverse thermal conductivity below the superconducting critical temperature of the optimally- (x = 0.35) and slightly over-doped (x = 0.55) samples. The evolution of this anomaly from the optimally electron-doped Ba(Fe0.94Co0.06)2As2 to hole-overdoped Ba0.45K0.55Fe2As2 suggests formation of a uniform superconducting gap on the electron pocket in the former and regions of a depressed gap on the hole-pocket in the latter.

18 pages, 6 figures

References in corpus (9)

• High-temperature superconductivity in iron-based materials
• Quantum oscillations and the Fermi surface in an underdoped high-Tc superconductor
• Electronic Structure and Doping in BaFe${}_2$As${}_2$ and LiFeAs: Density Functional Calculations
• Electronic structure of the iron-based superconductor LaOFeP
• Hall effect and resistivity study of the magnetic transition, carrier content and Fermi liquid behavior in Ba(Fe(1-x) Cox)2As2
• Universality of superconducting gaps in overdoped Ba0.3K0.7Fe2As2 observed by angle-resolved photoemission spectroscopy
• Fermiology and electronic homogeneity of the superconducting overdoped cuprate Tl-2201 revealed by quantum oscillations
• Crossover in the magnetic response of single-crystalline Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$ and Lifshitz critical point evidenced by Hall effect measurements
• The Lorenz number in CeCoIn${}_5$ inferred from the thermal and charge Hall currents

Cited by in corpus (4)

• Strong Correlations, Strong Coupling and s-wave Superconductivity in Hole-doped BaFe2As2 Single Crystals
• Superconducting phase diagrams of cuprates and pnictides as a key to the HTSC mechanism
• Anisotropy of the Seebeck and Nernst coefficients in parent compounds of the iron-based superconductors
• Local transformation of the Electronic Structure and Generation of Free Carriers in Cuprates and Ferropnictides under Heterovalent and Isovalent Doping