期刊
NANOMATERIALS
卷 12, 期 9, 页码 -出版社
MDPI
DOI: 10.3390/nano12091513
关键词
Kondo effect; graphene; electronic transport; quantum dots
类别
资金
- Irish Research Council through the Laureate Award 2017/2018 Grant [IRCLA/2017/169]
- Irish Research Council through Enterprise Partnership Scheme Grant [EPSPG/2017/343]
- Irish Research Council (IRC) [EPSPG/2017/343] Funding Source: Irish Research Council (IRC)
This article investigates a graphene-based two-channel charge-Kondo device and uncovers a rich phase diagram. It finds that the strong coupling pseudogap Kondo phase persists in the channel-asymmetric case. Furthermore, despite the vanishing density of states in the graphene leads, a finite linear conductance is observed at the frustrated critical point.
Nanoelectronic quantum dot devices exploiting the charge-Kondo paradigm have been established as versatile and accurate analogue quantum simulators of fundamental quantum impurity models. In particular, hybrid metal-semiconductor dots connected to two metallic leads realize the two-channel Kondo (2CK) model, in which Kondo screening of the dot charge pseudospin is frustrated. In this article, a two-channel charge-Kondo device made instead from graphene components is considered, realizing a pseudogapped version of the 2CK model. The model is solved using Wilson's Numerical Renormalization Group method, uncovering a rich phase diagram as a function of dot-lead coupling strength, channel asymmetry, and potential scattering. The complex physics of this system is explored through its thermodynamic properties, scattering T-matrix, and experimentally measurable conductance. The strong coupling pseudogap Kondo phase is found to persist in the channel-asymmetric two-channel context, while in the channel-symmetric case, frustration results in a novel quantum phase transition. Remarkably, despite the vanishing density of states in the graphene leads at low energies, a finite linear conductance is found at zero temperature at the frustrated critical point, which is of a non-Fermi liquid type. Our results suggest that the graphene charge-Kondo platform offers a unique possibility to access multichannel pseudogap Kondo physics.
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