The electronic specific heat of Ba1-xKxFe2As2 (x=0 to 1.0) from 2K to 380K

Abstract

Using a high-resolution differential technique we have determined the electronic specific heat coefficient gamma(T) of Ba1-xKxFe2As2 with x=0 to 1.0, at temperatures (T) from 2K to 380K and in magnetic fields H=0 to 13T. In the normal state gamma_n(x,T) increases strongly with x at low temperature, compatible with a mass renormalisation ~12 at x=1, and decreases weakly with x at high temperature. A superconducting transition is seen in all samples from x=0.2 to 1, with transition temperatures and condensation energies peaking sharply at x=0.4. Superconducting coherence lengths xi_{ab}~20Å and xi_c~3Å are estimated from an analysis of Gaussian fluctuations. For many dopings we see features in the H and T-dependences of gamma_s(T,H) in the superconducting state that suggest superconducting gaps in three distinct bands. A broad "knee" and a sharp mean-field-like peak are typical of two coupled gaps. However, several samples show a shoulder above the sharp peak with an abrupt onset at T_{c,s} and a T-dependence gamma_s(T)\propto\sqrt{1-T/T_{c,s}}. We provide strong evidence that the shoulder is not due to doping inhomogeneity and suggest it is a distinct gap with an unconventional T-dependence Delta_s(T)\propto(1-T/T_{c,s})^{0.75} near T_{c,s}. We estimate band fractions and T=0 gaps from 3-band alpha-model fits to our data and compare the x-dependences of the band fractions with spectroscopic studies of the Fermi surface.

20 pages, 23 figures, published in Physical Review B

References in corpus (25)

• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2
• Observation of Fermi-surface-dependent nodeless superconducting gaps in Ba0.6K0.4Fe2As2
• Anisotropic thermodynamic and transport properties of single crystalline (Ba${}_{1-x}$K${}_x$)Fe${}_2$As${}_2$ (x = 0 and 0.45)
• Coexistence of the spin-density-wave and superconductivity in the (Ba,K)Fe2As2
• Anisotropy in the electrical resistivity and susceptibility of superconducting BaFe${}_2$As${}_2$ single crystals
• Iron based superconductors: magnetism, superconductivity and electronic structure
• Momentum dependence of the superconducting gap in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• (pi,pi)-electronic order in iron arsenide superconductors
• Phase Diagram of Ba1-xKxFe2As2
• Fully Gapped Superconducting State Based on a High Normal State Quasiparticle Density of States in Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ Single Crystals
• 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
• Superfluid density and specific heat within self-consistent scheme for two-band superconductor
• Effects of magnetism and doping on the electron-phonon coupling in BaFe${}_2$As${}_2$
• Universal linear-temperature dependence of static magnetic susceptibility in iron-pnictides
• Quantum oscillations in the parent pnictide BaFe${}_2$As${}_2$ : itinerant electrons in the reconstructed state
• Competition of magnetism and superconductivity in underdoped (Ba1-xKx)Fe2As2
• Magnetoelastic Coupling in the Phase Diagram of Ba1-xKxFe2As2
• Ab initio lattice dynamics simulations and inelastic neutron scattering spectra for studying phonons in BaFe2As2: Effect of structural phase transition, structural relaxation and magnetic ordering
• Electronic structure of oxygen-free 38K superconductor Ba1-xKxFe2As2 in comparison with BaFe2As2 from first principles
• Thermodynamic properties of Ba1-xMxFe2As2 (M = La and K)
• Specific heat in KFe2As2 in zero and applied magnetic field
• The pseudogap ground state in high temperature superconductors
• Fermi surface of Ba{1-x}KxFe2As2 as probed by angle-resolved photoemission
• Thermodynamic properties of Bi2Sr2CaCu2O8 calculated from the electronic dispersion

Cited by in corpus (26)

• Superconducting properties of sulfur-doped iron selenide
• Strong Correlations, Strong Coupling and s-wave Superconductivity in Hole-doped BaFe2As2 Single Crystals
• The phase diagrams of iron-based superconductors: theory and experiments
• Quantum criticality in AFe2As2 with A = K, Rb, and Cs suppresses superconductivity
• Microscopic nature of correlations in multi-orbital AFe2As2 (A=K, Rb, Cs): Hund's coupling versus Coulomb repulsion
• BCS-like critical fluctuations with limited overlap of Cooper pairs in FeSe
• 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
• Nearly-critical spin and charge fluctuations in KFe2As2 observed by high-pressure NMR
• Ab-initio perspective on structural and electronic properties of iron-based superconductors
• Power Law Like Correlation between Condensation Energy and Superconducting Transition Temperatures in Iron Pnictide/Chalcogenide Superconductors: Beyond the BCS Understanding
• Muon spin rotation and infrared spectroscopy study of magnetism and superconductivity in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• Electric field gradient wave (EFGW) in iron-based superconductor Ba(0.6)K(0.4)Fe2As2 studied by Mössbauer spectroscopy
• Evolution of quasiparticle excitations with critical mass enhancement in superconducting AFe2As2 (A = K, Rb, and Cs)
• Muon spin rotation and infrared spectroscopy study of $B{a}_{1-x}N{a}_{x}F{e}_{2}A{s}_2$
• Scaling of the Fano effect of the in-plane Fe-As phonon and the superconducting critical temperature in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• Superconducting gap symmetry in BaFe${}_{1.9}$Ni${}_{0.1}$As${}_2$ superconductor
• Electronic specific heat in BaFe${}_{2-x}$Ni${}_x$As${}_2$
• Anomalous peak effect in iron-based superconductors Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$ ($x\approx$ 0.69 and 0.76) for magnetic-field directions close to the $ab$ plane and its possible relation to the spin paramagnetic effect
• Superconducting gap evolution in overdoped BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$ single crystals through nanocalorimetry
• Frozen spin ratio and the detection of Hund correlations
• Charge Transport in Ba${}_{1-x}$Rb${}_x$Fe${}_2$As${}_2$ Single Crystals
• Orbital and Pauli limiting effects in heavily doped Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• Specific heat in strongly hole-doped Iron-based superconductors
• In-plane magnetic field vs. temperature phase diagram of a quasi-2D frustrated multiband superconductor
• Multiband superconductivity and a deep gap minimum from the specific heat in KCa${}_2$(Fe${}_{1-x}$Ni${}_x$)${}_4$As${}_4$F${}_2$ ($x$ = 0, 0.05, 0.13)
• Calculation of the specific heat of optimally K-doped BaFe${}_2$As${}_2$