Massive enhancement of electron-phonon coupling in doped graphene by an electronic singularity

Abstract

The nature of the coupling leading to superconductivity in layered materials such as high-Tc superconductors and graphite intercalation compounds (GICs) is still unresolved. In both systems, interactions of electrons with either phonons or other electrons or both have been proposed to explain superconductivity. In the high-Tc cuprates, the presence of a Van Hove singularity (VHS) in the density of states near the Fermi level was long ago proposed to enhance the many-body couplings and therefore may play a role in superconductivity. Such a singularity can cause an anisotropic variation in the coupling strength, which may partially explain the so-called nodal-antinodal dichotomy in the cuprates. Here we show that the topology of the graphene band structure at dopings comparable to the GICs is quite similar to that of the cuprates and that the quasiparticle dynamics in graphene have a similar dichotomy. Namely, the electron-phonon coupling is highly anisotropic, diverging near a saddle point in the graphene electronic band structure. These results support the important role of the VHS in layered materials and the possible optimization of Tc by tuning the VHS with respect to the Fermi level.

arXiv comment8 pages

References in corpus (15)

• Two-Dimensional Gas of Massless Dirac Fermions in Graphene
• Experimental Observation of Quantum Hall Effect and Berry's Phase in Graphene
• Ultrathin epitaxial graphite: 2D electron gas properties and a route toward graphene-based nanoelectronics
• Superconductivity in the Intercalated Graphite Compounds C6Yb and C6Ca
• Synthesis and characterization of atomically-thin graphite films on a silicon carbide substrate
• Superconductivity of bulk CaC6
• An unusual isotope effect in a high-transition-temperature superconductor
• Electronic structure of superconducting graphite intercalate compounds: The role of the interlayer state
• Anisotropic electron-phonon interaction in the cuprates
• Intercalant-Driven Superconductivity in YbC${}_6$ and CaC${}_6$
• The Dichotomy between Nodal and Antinodal Quasiparticles in Underdoped (La${}_{2-x}$Sr${}_x$)CuO${}_4$ Superconductors
• Low energy excitations in graphite: The role of dimensionality and lattice defects
• Effect of Pressure on Superconducting Ca-intercalated Graphite CaC${}_6$
• Specific Heat of the Ca-Intercalated Graphite Superconductor CaC${}_6$
• Possibility of superconductivity in graphite intercalated with alkaline earths investigated with density functional theory

Cited by in corpus (5)

• Colloquium: Graphene spectroscopy
• Anisotropic Electron-Phonon Coupling and Dynamical Nesting on the Graphene Sheets in CaC6
• A statistical-thermodynamic analysis of stably ordered substitutional structures in graphene
• Kinetics of atomic ordering in metal-doped graphene
• Graphite intercalation compound KC${}_8$ revisited: a key to graphene