Gate-controlled Kondo screening in graphene: Quantum criticality and electron-hole asymmetry

Abstract

Magnetic impurities in neutral graphene provide a realization of the pseudogap Kondo model, which displays a quantum phase transition between phases with screened and unscreened impurity moment. Here, we present a detailed study of the pseudogap Kondo model with finite chemical potential mu. While carrier doping restores conventional Kondo screening at lowest energies, properties of the quantum critical fixed point turn out to influence the behavior over a large parameter range. Most importantly, the Kondo temperature T_K shows an extreme asymmetry between electron and hole doping. At criticality, depending on the sign of mu, T_K follows either the scaling prediction T_K ~ |mu| with a universal prefactor, or T_K ~ |mu|^x with x = 2.6. This asymmetry between electron and hole doping extends well outside the quantum critical regime and also implies a qualitative difference in the shape of the tunneling spectra for both signs of mu.

6 pages, 6 figs; (v2) extended discussion of RG flow, final version as published

References in corpus (8)

• Electric Field Effect in Atomically Thin Carbon Films
• The electronic properties of graphene
• The numerical renormalization group method for quantum impurity systems
• Phase transitions in the pseudogap Anderson and Kondo models: Critical dimensions, renormalization group, and local-moment criticality
• Tuning Kondo physics in Graphene with gate voltage
• Localized Spins on Graphene
• Theory of Scanning Tunneling Spectroscopy of Magnetic Adatoms in Graphene
• Upper-critical dimension in a quantum impurity model: Critical theory of the asymmetric pseudogap Kondo problem

Cited by in corpus (2)

• Orbital selective and tunable Kondo effect of magnetic adatoms on graphene: Correlated electronic structure calculations
• Magnetic Impurities in Graphene