Low temperature specific heat of the hole-doped Ba_{0.6}K_{0.4}Fe_2As_2 single crystals and electron-doped SmFeAsO_{0.9}F_{0.1} samples

Abstract

Low temperature specific heat (SH) was measured on the FeAs-based superconducting single crystals Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ and high pressure synthesized polycrystalline samples SmFeAsO${}_{0.9}$F${}_{0.1}$. It is found that the sharp SH anomaly $\Delta C/T{|}_{T_c}$ in Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ reaches an unexpected high value of 98 mJ/mol K${}^2$, about one order of magnitude larger than that of SmFeAsO${}_{0.9}$F${}_{0.1}$ ($6\sim 8$ mJ/mol K${}^2$) samples, suggesting very high normal state quasiparticle density of states in FeAs-122 than in FeAs-1111. Furthermore, we found that the electronic SH coefficient ${\gamma }_e(T)$ of Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ is weakly temperature dependent and increases almost linearly with the magnetic field in low temperature region, which may indicate that the hole-doped FeAs-122 system contains a dominant component with a full superconducting gap, although we cannot rule out the possibility of a small component with anisotropic or nodal gap. A detailed analysis reveals that the ${\gamma }_e(T)$ of Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ cannot be fitted with a single gap of s-wave symmetry probably due to the multigap effect. These results indicate clear difference between the properties of the superconducting state of the holed-doped Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ and the F-doped LnFeAsO (Ln = rare earth elements) systems, which we believe is originated from the complex Fermi surface structures in different systems.

9 pages, 10 figures

References in corpus (26)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Observation of Fermi-surface-dependent nodeless superconducting gaps in Ba0.6K0.4Fe2As2
• Superconductivity at 25 K in hole doped $(L{a}_{1-x}S{r}_x)OFeAs$
• Electronic Structure and Doping in BaFe${}_2$As${}_2$ and LiFeAs: Density Functional Calculations
• Superconductivity and Crystal Structures of (Ba1-xKx)Fe2As2 (x = 0 - 1)
• The BCS-like gap in superconductor SmFeAsO_0.85F_0.15
• The Unprecedented Giant Coupling of Fe-spin State and the As-As Hybridization in Iron-Pnictide
• ${}^{75}$As NMR studies of superconducting LaO${}_{0.9}$F${}_{0.1}$FeAs
• Microwave Penetration Depth and Quasiparticle Conductivity in PrFeAsO_1-y Single Crystals : Evidence for a Full-Gap Superconductor
• Electron Correlations in the Low Carrier Density LaFeAsO0.89F0.11 Superconductor (Tc = 28 K)
• Spin-singlet superconductivity with multiple gaps in PrO0.89F0.11FeAs
• (pi,pi)-electronic order in iron arsenide superconductors
• Multiple Nodeless Superconducting Gaps in (Ba0.6K0.4)Fe2As2 Superconductor from Angle-Resolved Photoemission Spectroscopy
• Field and Temperature Dependence of the Superfluid Density in LaO_{1-x}F_xFeAs Superconductors: A Muon Spin Relaxation Study
• Upper critical field, Hall effect and magnetoresistance in the iron-based layered superconductor LaFeAsO_{0.9}F_{0.1-δ}
• Hall effect and magnetoresistance in the normal state of the superconductor LaO${}_{0.9}$F${}_{0.1-x}$FeAs
• Upper critical field, anisotropy, and superconducting properties of Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$ single crystals
• 19-F NMR Investigation of Iron-pnictide Superconductor LaFeAsO(0.89)F(0.11)
• Growth and characterization of A_{1-x}K_xFe_2As_2 (A = Ba, Sr) single crystals with x=0 - 0.4
• Point-Contact Spectroscopy of Iron-Based Layered Superconductor LaO${}_{0.9}$F${}_{0.1-\delta }$FeAs
• Muon spin relaxation studies of magnetic order and superfluid density in antiferromagnetic NdOFeAs, BaFe2As2 and superconducting (Ba,K)Fe2As2
• Specific heat of the iron-based high-$T_c$ superconductor SmO${}_{1-x}$F${}_x$FeAs
• MuSR studies of RE(O,F)FeAs (RE = La, Nd, Ce) and LaOFeP systems: possible incommensurate/stripe magnetism and superfluid density
• Electron-hole Asymmetry and Quantum Critical Point in Hole-doped BaFe${}_2$As${}_2$
• Nodeless Superconductivity in the Noncentrosymmetric Superconductor $M{g}_{10}I{r}_{19}{B}_{16}$
• Possible nodeless superconductivity in the noncentrosymmetric superconductor Mg_(12-delta)Ir_19B_16

Cited by in corpus (34)

• High-temperature superconductivity in iron-based materials
• Observation of Lattice and Andreev Bound States of Vortices in Ba0.6K0.4Fe2As2 Single Crystals with Scanning Tunneling Microscopy/Spectroscopy
• Superconductivity in KCa${}_2$Fe${}_4$As${}_4$F${}_2$ with Separate Double Fe${}_2$As${}_2$ Layers
• Quasiparticle Heat Transport in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$: Evidence for a k-dependent Superconducting Gap without Nodes
• Non-exponential London penetration depth in Ba${}_{1-}$K${}_x$Fe${}_2$As${}_2$ single crystals
• Superconductivity induced by ruthenium substitution in an iron arsenide: investigation of SrFe2-xRuxAs2 (0 <= x <= 2)
• Superconducting Properties of the $s^{\pm }$-wave state: Fe-based superconductors
• Evolution of bulk superconductivity in SrFe2As2 with Ni substitution
• A doping dependent specific heat study of the superconducting gap in Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$
• Effect of annealing on the specific heat of Ba(Fe1-xCox)2As2
• Calorimetric Evidence of Strong-Coupling Multiband Superconductivity in Fe(Te0.57Se0.43) Single Crystal
• Nodeless superconductivity in K${}_x$Fe${}_{2-y}$Se${}_2$ single crystals revealed by low temperature specific heat
• Single-crystal growth and extremely high H_c2 of 12442-type Fe-based superconductor KCa_2Fe_4As_4F_2
• Anisotropic Phase Diagram and Superconducting Fluctuations in SmFeAsO0.85F0.15
• Evidence for multiple gaps in specific heat of LiFeAs crystals
• Overview on the physics and materials of the new superconductor KxFe2-ySe2
• Superconducting fluctuations in the reversible magnetization of the iron-pnictide $B{a}_{1-x}{K}_{x}F{e}_{2}A{s}_2$
• Lower Critical Field, Anisotropy, and Two-Gap Features of LiFeAs
• Specific Heat Discontinuity DeltaC vs Tc in Annealed Ba(Fe1-xCox)2As2
• Specific Heat Discontinuity, deltaC, at Tc in BaFe2(As0.7P0.3)2 - Consistent with Unconventional Superconductivity
• Strong Pauli paramagnetic effect in the upper critical field of KCa${}_2$Fe${}_4$As${}_4$F${}_2$
• Evidence of a universal and isotropic 2Δ/kBTC ratio in 122-type iron pnictide superconductors over a wide doping range
• Competition between superconductivity and magnetic/nematic order as a source of anisotropic superconducting gap in underdoped Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• Anomalous proximity effects at the interface of s and s+- superconductors
• Vortex state in iron-based superconductors with collinear antiferromagnetic cores
• Zn-impurity effect and interplay of $s_{\pm }$- and $s_{++}$-pairings in Fe-based superconductors
• Calorimetric Evidence for Nodes in the Overdoped Ba(Fe${}_{0.9}$Co${}_{0.1}$)${}_2$As${}_2$
• Unconventional gapping behavior in a kagome superconductor
• Disorder-sensitive superconductivity in the iron silicide Lu${}_2$Fe${}_3$Si${}_5$ studied by the Lu-site substitutions
• ${}^{75}$As NMR of Ba(Fe${}_{0.93}$Co${}_{0.07}$)${}_2$As${}_2$ in High Magnetic Field
• Electronic Behavior of Superconducting SmFeAsO0.75
• Emergence of Superconductivity from Fully Incoherent Normal State in an Iron-Based Superconductor (Ba${}_{0.6}$K${}_{0.4}$)Fe${}_2$As${}_2$
• Frozen spin ratio and the detection of Hund correlations
• Imaging the effect of drive on the low-field vortex melting phenomenon in Ba0.6K0.4Fe2As2 single crystal