Electron-Phonon mechanism for Superconductivity in Na${}_{0.35}$CoO${}_2$: Valence-Band Suhl-Kondo effect Driven by Shear Phonons

Abstract

To study the possible mechanism of superconductivity in Na${}_{0.35}$CoO${}_2$, we examine the interaction between all the relevant optical phonons (breathing and shear phonons) and $t_{2g}(a_{1g}+e_g^{\prime })$-electrons of Co-ions, and study the transition temperature for a s-wave superconductivity. The obtained $T_{\mathrm{c}}$ is very low when the $e_g^{\prime }$-valence-bands are far below the Fermi level. However, $T_{\mathrm{c}}$ is strongly enhanced when the top of the $e_g^{\prime }$-valence-bands is close to the Fermi level (say -50meV), thanks to interband hopping of Cooper pairs caused by shear phonons. This ``valence-band Suhl-Kondo mechanism'' due to shear phonons is significant to understand the superconductivity in Na${}_{0.35}$CoO${}_2$. By the same mechanism, the kink structure of the band-dispersion observed by ARPES, which indicates the strong mass-enhancement ($m^{\ast }/m\sim 3$) due to optical phonons, is also explained.

arXiv comment5 pages, 4 figures; v2:Added references, published in J. Phys. Soc. Jpn

References in corpus (15)

• Fermi surface evolution and Luttinger theorem in Na${}_x$CoO${}_2$: a systematic photoemission study
• Origin of the Weak Pseudo-gap Behaviors in Na_{0.35}CoO_2: Absence of Small Hole Pockets
• Magnetic Correlation of NaxCoO2 and Successive Phase Transitions of Na0.5CoO2 -NMR and Neutron Diffraction Studies-
• 59Co NMR study of the Co states in superconducting and anhydrous cobaltates
• Weak Magnetic Order in the Bilayered-hydrate Na${}_x$CoO${}_2\cdot y$H${}_2$O Structure Probed by Co Nuclear Quadrupole Resonance - Proposed Phase Diagram in Superconducting Na${}_x$CoO${}_2\cdot$ $y$H${}_2$O
• 59Co-NMR Knight Shift of Aligned Crystals and Polycrystalline Samples of Superconducting Na0.3CoO2.1.3H2O
• The infrared spectrum of Na_0.57CoO_2
• First principles lattice dynamics of NaCoO${}_2$
• Ferromagnetic and triplet-pairing instabilities controlled by the trigonal distortion of the CoO_6 octahedra in Na_xCoO_2*yH_2O
• 17-O NMR studies of a triangular-lattice superconductor Na{x}CoO{2}yH{2}O
• ${}^{17}$O NMR Measurements on Superconducting Na${}_{0.35}$CoO${}_2\cdot y$H${}_2$O
• Anisotropic Behavior of Knight Shift in Superconducting State of Na_xCoO_2yH_2O
• Electron-boson mode coupling and the pseudogap of Na${}_x$CoO${}_2$ by infrared spectroscopy
• Theory of anisotropic s-wave superconductivity with point-node like gap minima: analysis of (Y,Lu)Ni_2B_2C
• Cooperative effect of phonons and electronic correlations for superconductivity in cobaltates

Cited by in corpus (13)

• Origin of Orthorhombic Transition, Magnetic Transition, and Shear Modulus Softening in Iron Pnictide Superconductors: Analysis based on the Orbital Fluctuation Theory
• Emergence of Fully-Gapped $s_{++}$-wave and Nodal d-wave States Mediated by Orbital- and Spin-Fluctuations in Ten-Orbital Model for KFe${}_2$Se${}_2$
• Angle-resolved photoemission study of cobalt oxide superconductor NaxCoO2.yH2O : Observation of the Fermi surface
• Efficient fluctuation exchange approach to low-temperature spin fluctuations and superconductivity: from the Hubbard model to Na${}_x$CoO${}_2\cdot y$H${}_2$O
• Deformation of Electronic Structures Due to CoO6 Distortion and Phase Diagrams of NaxCoO2.yH2O
• Electron-phonon interaction in the lamellar cobaltate Na${}_x$CoO${}_2$
• s-wave Superconductivity due to Suhl-Kondo Mechanism in Na${}_x$CoO${}_2\cdot y$H${}_2$O: Effect of Coulomb Interaction and Trigonal Distortion
• Electron-phonon interaction dressed by electronic correlations near charge ordering as the origin for superconductivity in cobaltates
• Pairing mechanism of unconventional superconductivity in doped Kane-Mele model
• Pressure dependence of the superconducting transition and electron correlations in Na_xCoO_2 \cdot 1.3H_2O
• Charge order and phonon renormalizations: Possible implications for cobaltates
• Weak-Coupling Theory for Multiband Superconductivity Induced by Jahn-Teller Phonons
• Robustness of s-wave superconductivity against Coulomb interactions in Na${}_x$CoO${}_2$