Volume 90, Number 2, April 2010
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||19 May 2010|
Gate-controlled Kondo screening in graphene: Quantum criticality and electron-hole asymmetry
Institut für Theoretische Physik, Universität zu Köln - Zülpicher Str. 77, 50937 Köln, Germany, EU
2 Centro Atomico Bariloche - 8400 San Carlos de Bariloche, Argentina
Accepted: 13 April 2010
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 μ. 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 TK shows an extreme asymmetry between electron and hole doping. At criticality, depending on the sign of μ, TK follows either the scaling prediction TK |μ| with a universal prefactor, or TK |μ|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 μ.
PACS: 75.20.hr – Local moment in compounds and alloys; Kondo effect, valence fluctuations, heavy fermions / 71.55.Ht – Other nonmetals / 73.20.Hb – Impurity and defect levels; energy states of adsorbed species
© EPLA, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.