Evidence of a multiple boson emission in Sm${}_{1-x}$Th${}_x$OFeAs

Abstract

We studied a reproducible fine structure observed in dynamic conductance spectra of Andreev arrays in Sm${}_{1-x}$Th${}_x$OFeAs superconductors with various thorium concentrations ($x=0.08-0.3$) and critical temperatures $T_c=26-50$\,K. This structure is unambiguously caused by a multiple boson emission (of the same energy) during the process of multiple Andreev reflections. The directly determined energy of the bosonic mode reaches ${\epsilon }_0=14.8\pm 2.2$\,meV for optimal compound. Within the studied range of $T_c$, this energy as well as the large ${\Delta }_L$ and the small ${\Delta }_S$ superconducting gaps, nearly scales with critical temperature with the characteristic ratio ${\epsilon }_0/k_B{T}_c\approx 3.2$ (and $2{\Delta }_L/k_B{T}_c\approx 5.3$, correspondingly) resembling the expected energy ${\Delta }_L+{\Delta }_S$ of spin resonance and spectral density enhancement in $s^{\pm }$ and $s^{++}$ states, respectively.

arXiv comment10 pages, 4 figures

References in corpus (44)

• Unconventional sign-reversing superconductivity in LaFeAsO_(1-x)F_x
• The Puzzle of High Temperature Superconductivity in Layered Iron Pnictides and Chalcogenides
• High-temperature superconductivity in iron-based materials
• Gap symmetry and structure of Fe-based superconductors
• Antiferromagnetic order and spin dynamics in iron-based superconductors
• Orbital Fluctuation Mediated Superconductivity in Iron Pnictides: Analysis of Five Orbital Hubbard-Holstein Model
• High Temperature Superconductivity in Iron Pnictides and Chalcogenides
• AC JOSEPHSON EFFECT IN A SINGLE QUANTUM CHANNEL
• Theory of magnetic excitations in iron-based layered superconductors
• Spin-singlet superconductivity with multiple gaps in PrO0.89F0.11FeAs
• Neutron scattering as a probe of the Fe-pnicitide superconducting gap
• Using Gap Symmetry and Structure to Reveal the Pairing Mechanism in Fe-based Superconductors
• Electronic Structure of Fe-Based Superconductors
• 75As NQR/NMR Studies on Oxygen-deficient Iron-based Oxypnictide Superconductors LaFeAsO_{1-y} (y=0,0.25,0.4) and NdFeAsO_{0.6}
• Quantum Materials: Shape Resonances in Superstripes
• Directional point-contact Andreev-reflection spectroscopy of Fe-based superconductors: Fermi surface topology, gap symmetry, and electron-boson interaction
• Multigap superconductivity and strong electron-boson coupling in Fe-based superconductors: A point-contact Andreev-reflection study of Ba(Fe1-xCox)2As2 single crystals
• High-pressure flux growth, structural, and superconducting properties of LnFeAsO (Ln = Pr, Nd, Sm) single crystals
• Experimental evidence of two-band behavior of MgB2
• Phonon Density of States of LaFeAsO1-xFx
• Evidence for two-gap nodeless superconductivity in SmFeAsO${}_{0.8}$F${}_{0.2}$ from point-contact Andreev-reflection spectroscopy
• Isoelectronic Ru substitution at Fe-site in Sm(Fe1-xRux)As(O0.85F0.15) compound and its effects on structural, superconducting and normal state properties
• Possible two-gap superconductivity in NdFeAs(O,F) probed by point-contact Andreev-reflection spectroscopy
• Evidence of a spin resonance mode in the iron-based superconductor Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ from scanning tunneling spectroscopy
• Transport and superconducting properties of Fe-based superconductors: SmFeAs(O1-x Fx) versus Fe1+y (Te1-x, Sex)
• Th substituted SmFeAsO: structural details and superconductivity with Tc above 50 K
• Neutron-Inelastic-Scattering Peak by Dissipationless Mechanism in the s++ -wave State in Iron-based Superconductors
• Break-junction technique in application to layered superconductors (Review article)
• Superconducting state in Fe-based materials and spin-fluctuation theory of pairing
• Interaction-induced singular Fermi surface in a high-temperature oxypnictide superconductor
• Phonon Density of States in Nd(O${}_{1-x}$F${}_x$)FeAs
• Local quasiparticle density of states of superconducting SmFeAsO$1-x$F$x$ single crystals: Evidence for spin-mediated pairing
• Andreev spectroscopy of iron-based superconductors: temperature dependence of the order parameters and scaling of the ${\Delta }_{L,S}$ with $T_C$
• Investigation of Superconducting Gap Structure in TbFeAsO${}_{0.9}$F${}_{0.1}$ using Point Contact Andreev Reflection
• Experimental study of intrinsic multiple Andreev reflections effect in GdO(F)FeAs superconductor array junctions
• Leggett mode in a strong-coupling model of iron arsenide superconductors
• Evolution of Superconducting Gaps in Th-Substituted Sm${}_{1-x}$Th${}_x$OFeAs Studied by Multiple Andreev Reflection Spectroscopy
• Upper critical field, superconducting energy gaps, and Seebeck coefficient in La0.8Th0.2OFeAs
• Determination of Superconducting Gap of SmFeAsFxO1-x Superconductors by Andreev Reflection Spectroscopy
• Spin resonance peak in Fe-based superconductors with unequal gaps
• Disorder effects in pnictides : a tunneling spectroscopy study
• THz phonon spectroscopy of doped superconducting cuprates
• Variety of c-axis collective excitations in layered multigap superconductors
• Intrinsic Multiple Andreev Reflections in layered Th-doped Sm${}_{1-x}$Th${}_x$OFeAs

Cited by in corpus (4)

• Electron and Superconducting Properties of the AFeAs (A= Li, Na) Family Alkali-Metal Pnictides: Current Stage of the Research (mini-review)
• Superconducting Order Parameter and Bosonic Mode in Hydrogen-Substituted NdFeAsO${}_{0.6}$H${}_{0.36}$ Revealed by Multiple Andreev Reflection Spectroscopy
• Superconducting Order Parameters in overdoped BaFe${}_{1.86}$Ni${}_{0.14}$As${}_2$ Revealed by Multiple Andreev Reflection Spectroscopy of Planar Break-Junctions
• Direct observation of the spin exciton in Andreev spectroscopy of iron-based superconductors