Isotope effect and the role of phonon in the Fe-based superconductors

Abstract

We studied the isotope effect of phonon in the Fe-based superconductors using a phenomenological two band model for the sign-changing s-wave ($\pm$s-wave) state. Within this mean-field model, we showed that the large isotope effect is not inconsistent with the $\pm$s-wave pairing state and its high transition temperature. In principle, a large phonon isotope coefficient $\alpha$ implies a large phonon coupling constant. However, the asymmetric density of states (DOS) between two bands substantially enhances the value of $\alpha$, so that a moderate value of the phonon coupling constant (${\lambda }_{\mathrm{ph}}\approx 0.4$) can produce a very large value of $\alpha$ ($\approx 0.4$) as well as a high transition temperature together with an antiferromagnet (AFM)-induced interaction.

5 pages, 2 figures

References in corpus (18)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• Superconductivity at 41 K and its competition with spin-density-wave instability in layered CeO${}_{1-x}$F${}_x$FeAs
• Observation of Fermi-surface-dependent nodeless superconducting gaps in Ba0.6K0.4Fe2As2
• Magnetism, superconductivity, and pairing symmetry in Fe-based superconductors
• Is LaO${}_{1-x}$F${}_x$FeAs an electron-phonon superconductor ?
• Funtional Renormalization Group Study of the Pairing Symmetry and Pairing Mechanism of the FeAs Based High Temperature Superconductors
• Theory of magnetic excitations in iron-based layered superconductors
• Evolution from Itinerant Antiferromagnet to Unconventional Superconductor with Fluorine Doping in La(O_{1-x}F_{x})FeAs Revealed by ^{75}As and ^{139}La Nuclear Magnetic Resonance
• ${}^{75}$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
• Spin-singlet superconductivity with multiple gaps in PrO0.89F0.11FeAs
• NMR relaxation rate in superconducting pnictides: extended $s_{\pm }$ scenario
• Lattice and Magnetic structures of PrFeAsO, PrFeAsO0.85F0.15 and PrFeAsO0.85
• 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
• Effects of phonon interaction on the pairing in the high-T$c$ superconductors

Cited by in corpus (1)

• Orbital Fluctuation Theory in Iron Pnictides: Effects of As-Fe-As Bond Angle, Isotope Substitution, and $Z^2$-Orbital Pocket on the Superconductivity