Thermal conductivity and annealing effects in the iron-based superconductor FeSe${}_{0.3}$Te${}_{0.7}$

Abstract

Thermal conductivity measurements in magnetic fields have been carried out for FeSe${}_{0.3}$Te${}_{0.7}$ single crystals as-grown and annealed at 400 {\degree}C for 100 h in vacuum ($\sim$ 10${}^{-4}$ Pa). It has been found that the thermal conductivity in the {\it ab}-plane, {\kab}, of the annealed crystal shows an enhancement at low temperatures just below the superconducting transition temperature, {\tc}, owing to the thermal conductivity due to quasiparticles, while {\kab} of the as-grown crystal does not. This suggests that FeSe${}_{1-x}$Te${}_x$ is a strongly correlated electron system. It has also been found that both the degree of the enhancement of {\kab} just below {\tc} and the behavior of the suppression of {\kab} by the application of magnetic field for the annealed crystal depend on the thickness of the crystal. These results indicate that bulk superconductivity is absent in the as-grown crystal, appears only in the surface area in the annealed-thick crystal and appears in the almost whole region in the annealed-thin crystal. It has been concluded that the excess Fe included in the as-grown crystal is removed from the surface through the vacuum-annealing.

15 pages, 4 figures

References in corpus (12)

• Superconductivity close to magnetic instability in Fe(Se1-xTex)0.82
• Tellurium substitution effect on superconductivity of the alpha-phase Iron Selenide
• Incommensurate magnetic order in the alpha-Fe(Te,Se) superconductor systems
• First-order magnetic and structural phase transitions in Fe${}_{1+y}$Se${}_x$Te${}_{1-x}$
• Bulk Superconductivity at 14 K in Single Crystals of Fe1+yTexSe1-x
• Electron Correlations in the Low Carrier Density LaFeAsO0.89F0.11 Superconductor (Tc = 28 K)
• Thermal properties of SmFeAs(O1-xFx) as probe of the interplay between electrons and phonons
• Specific-heat study of superconducting and normal states in FeSe1-xTex (0.6<=x<=1) single crystals: Strong-coupling superconductivity, strong electron-correlation, and inhomogeneity
• Anomalous Temperature Dependence of the Superfluid Density Caused by Dirty-to-Clean Crossover in FeSe${}_{0.4}$Te${}_{0.6}$ Single Crystals
• Effects of Annealing under Tellurium Vapor for Fe${}_{1.03}$Te${}_{0.8}$Se${}_{0.2}$ Single Crystals
• Effect of Vacuum Annealing on Superconductivity in Fe(Se,Te) Single Crystals
• Field-induced magnetic order in La$sub2-x$Sr$subx$CuO$sub4$ (x = 0.10, 0.115, 0.13) studied by in-plane thermal conductivity measurements

Cited by in corpus (1)

• Superconducting Gap and Symmetry in FeSe_1-x_Te_x_ Studied by Specific Heat in Magnetic Fields