Nodeless two-gap superconductivity in stoichiometric iron pnictide LiFeAs

Abstract

The variations of in- and inter- plane London penetration depths, $\Delta \lambda (T)$, were measured using a tunnel diode resonator in single crystals of the intrinsic pnictide superconductor LiFeAs. This compound appears to be in the clean limit with a residual resistivity of 4 ($T\to 0$) to 8 ($T_c$) $\mu \Omega \cdot$cm and $RRR$ of 65 to 35, respectively. The superfluid density, ${\rho }_s(T)={\lambda }^2(0)/{\lambda }^2(T)$, is well described by the self-consistent two-gap $\gamma -$model. Together with the previous data, our results support the universal evolution of the superconducting gap from nodeless to nodal upon departure from optimal doping. We also conclude that pairbreaking scattering plays an important role in the deviation of the low-temperature behavior of $\lambda (T)$ from exponential in Fe-based compounds.

References in corpus (28)

• Unconventional sign-reversing superconductivity in LaFeAsO_(1-x)F_x
• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Pnictogen height as a possible switch between high-T_c nodeless and low-T_c nodal pairings in the iron based superconductors
• Resonant Spin Excitation in the High Temperature Superconductor Ba0.6K0.4Fe2As2
• Neutron Scattering from Magnetic Excitations in Bi_2 Sr_2 Ca_2 O_8+delta
• Superconductivity up to 30 K in the vicinity of quantum critical point in BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Theory of magnetic excitations in iron-based layered superconductors
• Two-dimensional resonant magnetic excitation in BaFe1.84Co0.16As2
• Microwave Penetration Depth and Quasiparticle Conductivity in PrFeAsO_1-y Single Crystals : Evidence for a Full-Gap Superconductor
• Spin Gap and Resonance at the Nesting Wavevector in Superconducting FeSe0.4Te0.6
• Line nodes in the energy gap of high-temperature superconducting BaFe_2(As_{1-x}P_x)_2 from penetration depth and thermal conductivity measurements
• Magnetic Resonant Mode in the Single-Layer High Temperature Superconductor Tl${}_2$Ba${}_2$Cu${}_{6+\delta }$
• Evidence for nodal superconductivity in LaFePO
• Neutron scattering as a probe of the Fe-pnicitide superconducting gap
• Evidence for superconducting gap nodes in the zone-centered hole bands of KFe2As2 from magnetic penetration-depth measurements
• Three-dimensional Resonance in superconducting BaFe${}_{1.9}$Ni${}_{0.1}$As${}_2$
• Microwave Surface-Impedance Measurements of the Magnetic Penetration Depth in Single Crystal Ba1-xKxFe2As2 Superconductors: Evidence for a Disorder-Dependent Superfluid Density
• Static and Dynamic Magnetism in Underdoped Superconductor BaFe${}_{1.92}$Co${}_{0.08}$As${}_2$
• ^{31}P and ^{75}As NMR evidence for a residual density of states at zero energy in superconducting BaFe_2(As_{0.67}P_{0.33})_2
• Structure of Neutron-Scattering Peak in both s++ wave and s+- wave states of an Iron pnictide Superconductor
• High energy spin excitations in BaFe2As2
• Neutron Scattering Resonance and the Fe-pnictide Superconducting Gap
• Magnetic penetration depth of single crystal SmFeAsO_{1-x}F_y: a fully gapped superconducting state
• Spin gap and magnetic resonance in superconducting BaFe${}_{1.9}$NiAs${}_2$
• Unusual Relationship between Magnetism and Superconductivity in FeTe${}_{0.5}$Se${}_{0.5}$
• Degradation of superconductivity and spin fluctuations by electron over-doping in LaFeAsO${}_{1-x}$F${}_x$
• Inelastic neutron scattering study on the resonance mode in an optimally doped superconductor LaFeAsO${}_{0.92}$F${}_{0.08}$

Cited by in corpus (5)

• Crossover from weak to strong pairing in unconventional superconductors
• Small anisotropy of the lower critical field and $s_{\pm }$-wave two-gap feature in single crystal LiFeAs
• Superconducting fluctuations in isovalently-substituted BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$: Possible observation of multiband effects
• Pairing mechanism for nodal $s$-wave superconductivity in BaFe${}_2$(As,P)${}_2$: Analysis beyond Migdal-Eliashberg formalism
• Enhancement of the critical current by surface irregularities in Fe-based superconductors