Nodeless energy gaps of single-crystalline Ba0.68K0.32Fe2As2 as seen via 75As NMR

Abstract

We report ${}^{75}$As nuclear magnetic resonance studies on a very clean hole-doped single-crystal Ba${}_{0.68}$K${}_{0.32}$Fe${}_2$As${}_2$ ($T_{\mathrm{c}}=38.5$ K). The spin-lattice relaxation rate $1/T_1$ shows an exponential decrease below $T\simeq 0.45T_{\mathrm{c}}$ down to $T\simeq 0.11T_{\mathrm{c}}$, which indicates a fully opened energy gap. From the ratio $(T_1{)}_c/(T_1{)}_a$, where $a$ and $c$ denote the crystal directions, we find that the antiferromagnetic spin fluctuation is anisotropic in the spin space above $T_{\mathrm{c}}$. The anisotropy decreases below $T_{\mathrm{c}}$ and disappears at $T\to 0$. We argue that the anisotropy stems from spin-orbit coupling whose effect vanishes when spin-singlet electron pairs form with a nodeless gap.

10 pages, 6 figures

References in corpus (18)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• Observation of Fermi-surface-dependent nodeless superconducting gaps in Ba0.6K0.4Fe2As2
• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• A minimal two-band model for the superconducting Fe-pnictides
• Funtional Renormalization Group Study of the Pairing Symmetry and Pairing Mechanism of the FeAs Based High Temperature Superconductors
• ${}^{75}$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
• Commensurate Itinerant Antiferromagnetism in BaFe2As2: 75As-NMR Studies on a Self-Flux Grown Single Crystal
• Spin-singlet superconductivity with multiple gaps in PrO0.89F0.11FeAs
• Properties of a two orbital model for oxypnictide superconductors: Magnetic order, B_2g spin-singlet pairing channel, and its nodal structure
• Experimental Consequences of the S-wave $\cos (k_x)\cdot \cos (k_y)$ Superconductivity in the Iron-Pnictides
• Possible pairing states of the Fe-based superconductors
• Strong-coupling Spin-singlet Superconductivity with Multiple Full Gaps in Hole-doped Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ Probed by Fe-NMR
• 75As NMR Study of Hole-Doped Superconductor Ba1-xKxFe2As2 (Tc = 38K)
• ${}^{75}$As NQR and NMR studies of superconductivity and electron correlations in iron arsenide Li${}_x$FeAs
• Two superconducting gaps in LaFeAsO0.92F0.08 revealed by 75As nuclear quadrupole resonance

Cited by in corpus (43)

• Gap symmetry and structure of Fe-based superconductors
• Hidden $T$-Linear Scattering Rate in Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ Revealed by Optical Spectroscopy
• Ferromagnetic Spin Fluctuation and Unconventional Superconductivity in Rb${}_2$Cr${}_3$As${}_3$ revealed by ${}^{75}$As NMR and NQR
• Antiferromagnetic Spin Fluctuation above the Superconducting Dome and the Full-Gaps Superconducting State in LaFeAsO1-xFx Revealed by 75As-Nuclear Quadrupole Resonance
• Uniaxial strain control of spin-polarization in multicomponent nematic order of BaFe${}_2$As${}_2$
• Microscopic coexistence of antiferromagnetic order and superconductivity in Ba${}_{0.77}$K${}_{0.23}$Fe${}_2$As${}_2$
• Magnetic fluctuations and superconducting properties of CaKFe4As4 studied by 75As NMR
• Mn local moments prevent superconductivity in iron-pnictides Ba(Fe 1-x Mn x)2As2
• Impurities in multiband superconductors
• New Superconductivity Dome in LaFeAsO${}_{1-x}$F${}_x$ Accompanied by Structural Transition
• Odd parity pairing and nodeless anti-phase $s^{\pm }$ in Iron-Based Superconductors
• Orbital Order and Spin Nematicity in the Tetragonal Phase of Electron-doped Iron-Pnictides NaFe${}_{1-x}$Co${}_x$As
• Electron Mass Enhancement near a Nematic Quantum Critical Point in NaFe${}_{1-x}$Co${}_x$As
• NMR and NQR studies on transition-metal arsenide superconductors LaRu2As2, KCa2Fe4As4F2, and A2Cr3As3
• Competition between superconductivity and magnetic/nematic order as a source of anisotropic superconducting gap in underdoped Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• Thermodynamic Study of Nodal Structure and Multiband Superconductivity of KFe2As2
• Interplane resistivity of underdoped single crystals (Ba${}_{1-x}$K${}_x$)Fe${}_2$As${}_2$, $0\le x<0.34$
• Microscopic coexistence of superconductivity and antiferromagnetism in underdoped Ba(Fe1-xRux)2As2
• Emergent magnetic degeneracy in iron pnictides due to the interplay between spin-orbit coupling and quantum fluctuations
• Unconventional multiband superconductivity with nodes in single-crystalline SrFe2(As_0.65P_0.35)2 as seen via 31P-NMR and specific heat
• Multigap superconductivity in locally non-centrosymmetric SrPtAs: An As nuclear quadrupole resonance investigation
• Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba${}_{0.67}$K${}_{0.33}$Fe${}_2$As${}_2$
• Nanoscale textured superconductivity in Ru-substituted BaFe2As2 : a challenge to a universal phase diagram for the pnictides
• Antiferromagnetic spin correlations and pseudogap-like behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity
• Magnetic phase diagram of the iron pnictides in the presence of spin-orbit coupling: Frustration between $C_2$ and $C_4$ magnetic phases
• Superconductivity and normal state properties of single-crystalline Tl0.47Rb0.34Fe1.63Se2 as seen via 77Se and 87Rb NMR
• Magnetism and superconductivity in Sr${}_2$VFeAsO${}_3$ revealed by ${}^{75}$As- and ${}^{51}$V-NMR under elevated pressures
• Spin excitation anisotropy in optimal-isovalent-doped superconductor BaFe2(As0.7P0.3)2
• Peculiar Phase Diagram with Isolated Superconducting Regions in ThFeAsN${}_{1-x}$O${}_x$
• Optical observation of spin-density-wave fluctuations in Ba122 iron-based superconductors
• Review of nuclear magnetic resonance studies on iron-based superconductors
• NMR evidence for an intimate relationship between antiferromagnetic spin fluctuations and extended s-wave superconductivity in mono-crystalline SrFe2(As_{1-x}P_{x})2
• Spin-pairing and penetration depth measurements from nuclear magnetic resonance in NaFe${}_{0.975}$Co${}_{0.025}$As
• Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV${}_3$Sb${}_5$
• Multiple Superconducting Gaps, Anisotropic Spin Fluctuations and Spin-Orbit Coupling in Iron-Pnictides
• Single crystal growth of and hyperfine couplings in the spin-triplet superconductor K${}_2$Cr${}_3$As${}_3$
• Structural Phase Transition, Antiferromagnetism and Two Superconducting Domes in LaFeAsO${}_{1-x}$F${}_x$ (0 $<x\le$ 0.75)
• Weak Spin Fluctuation with Finite Wave Vector and Superconducting Gap Symmetry in KxFe2-ySe2: 77Se Nuclear Magnetic Resonance
• Magnetic field dependence of spin-lattice relaxation in the s$\pm$ state of Ba${}_{0.67}$K${}_{0.33}$Fe${}_2$As${}_2$
• Cooper Pairing in A Doped 2D Antiferromagnet with Spin-Orbit Coupling
• Unconventional Coherence Peak in Cuprate Superconductors
• Nodal superconducting gap in LiFeP revealed by NMR: contrast with LiFeAs
• Microscopic evidence for Fulde-Ferrel-Larkin-Ovchinnikov state and multiband effects in KFe${}_2$As${}_2$