Gate-tuned two-channel Kondo screening by graphene leads: Universal scaling of the nonlinear conductance

TL;DR

This paper investigates the universal scaling behavior of nonlinear conductance in a two-channel Kondo system within graphene leads, using the non-crossing approximation to analyze the crossover from Kondo screening to local moment phases.

Contribution

It introduces a detailed analysis of the universal conductance scaling functions in a pseudogap Kondo model relevant for doped graphene, extending understanding of Kondo physics in such systems.

Findings

Universal conductance scaling functions are derived.

The crossover from Kondo screening to local moment phase is characterized.

Results are related to recent experimental observations in graphene.

Abstract

Based on the non-crossing approximation, we calculate both the linear and nonlinear conductance within the two-lead two-channel single-impurity Anderson model where the conduction electron density of states vanishes in a power-law fashion $ \propto |\omega-\mu_F|^r$ with $r=1$ near the Fermi energy, appropriate for an hexagonal system. For given gate voltage, we address the universal crossover from a two-channel Kondo phase, argued to occur in doped graphene, to an unscreened local moment phase. We extract universal scaling functions in conductance governing charge transfer through the two-channel pseudogap Kondo impurity and discuss our results in the context of a recent scanning tunneling spectroscopy experiment on Co-doped graphene.