Signatures of non-adiabatic superconductivity in lithium-decorated graphene

Abstract

Recent experimental studies confirmed that a long searched conventional superconducting phase in graphene can be induced via lithium deposition. However, the canonical character of the lithium-decorated graphene (LiC${}_6$) superconductor postulated therein, as defined by the Bardeen-Cooper-Schrieffer (BCS) theory, is ambiguous due to the moderate electron-phonon coupling constant and low Fermi energy in this material. Herein, this issue is addressed within the Migdal-Eliashberg formalism and beyond it via the first-order electron-phonon vertex corrections, to account for the potentially pivotal effects, hitherto not captured. The conducted analysis yields similar value of the metal-superconductor transition temperature as in the previous studies ($T_C\sim 6$ K), yet for a weaker depairing electron correlations, which magnitude in the non-adiabatic regime approaches predictions of the Morel-Anderson model. Moreover, the characteristic ratio of the pairing gap and the inverse temperature is found to notably exceeds estimates of the BCS theory. In a results, it is argued that the superconducting state in LiC${}_6$ may have non-canonical character strongly influenced by the non-adiabatic and retardation effects. Moreover, discussed phase appears as a vital case study, which suggests that other two-dimensional superconductors of hexagonal structure may exhibit similar non-canonical behavior as LiC${}_6$.

arXiv comment7 pages, 2 figures

References in corpus (28)

• Electric Field Effect in Atomically Thin Carbon Films
• The electronic properties of graphene
• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• Bipolar supercurrent in graphene
• Superconductivity in the Intercalated Graphite Compounds C6Yb and C6Ca
• Chiral superconductivity from repulsive interactions in doped graphene
• Highly crystalline 2D superconductors
• Evidence for superconductivity in Li-decorated monolayer graphene
• Prediction of phonon-mediated superconductivity in borophene
• Competing many-body instabilities and unconventional superconductivity in graphene
• Direct Observation of Superconductivity in Calcium-Intercalated Bilayer Graphene by in situ Electrical Transport Measurements
• Resonating valence bonds and mean-field d-wave superconductivity in graphite
• Doped graphane: a prototype high-Tc electron-phonon superconductor
• Two-dimensional Superconductors with Atomic-scale Thicknesses
• Breakdown of the Migdal approximation at Lifshitz transitions with giant zero-point motion in H3S superconductor
• Possible Triplet $p+ip$ Superconductivity in Graphene at Low Filling
• Phonon-mediated Superconductivity in Silicene
• First-principles calculations of the superconducting properties in Li-decorated monolayer graphene within the anisotropic Migdal-Eliashberg formalism
• High $T_c$ superconductivity in MgB${}_2$ by nonadiabatic pairing
• Possibility of superconductivity due to electron-phonon interaction in graphene
• Substrate enhanced superconductivity in Li-decorated graphene
• Retardation effects and the Coulomb pseudopotential in the theory of superconductivity
• Strain Enhanced Superconductivity in Li-Doped Graphene
• Electron-phonon properties and superconductivity of doped antimonene
• What are the experimentally observable effects of vertex corrections in superconductors?
• The physical origin of the electron-phonon vertex correction
• Nonadiabatic Superconductivity and Vertex Corrections in Uncorrelated Systems
• Superconducting Phases in Lithium Decorated Graphene LiC 6

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• Quantifying nonadiabaticity in major families of superconductors
• $d$-wave superconductivity as a model for diborides apart MgB${}_2$
• Towards room-temperature superconductivity
• Phase Stability and Superconductivity in Hydrogenated and Lithiated Janus GaXS2 (X = Ga, In) Monolayers
• The phonon-mediated superconductivity in bismuthates by non-adiabatic pairing