Gate-tunable split Kondo effect in a carbon nanotube quantum dot

Abstract

We show a detailed investigation of the split Kondo effect in a carbon nanotube quantum dot with multiple gate electrodes. It is found that the splitting decreases for increasing magnetic field, to result in a recovered zero-bias Kondo resonance at finite magnetic field. Surprisingly, in the same charge state, but under different gate-configurations, the splitting does not disappear for any value of the magnetic field, but we observe an avoided crossing of two high-conductance lines. We think that our observations can be understood in terms of a two-impurity Kondo effect with two spins coupled antiferromagnetically. The exchange coupling between the two spins can be influenced by a local gate, and the non-recovery of the Kondo resonance for certain gate configurations is explained by the existence of a small antisymmetric contribution to the exchange interaction between the two spins.

12 pages, 4 figures, published version

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Cited by in corpus (5)

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• Ultra long spin decoherence times in graphene quantum dots with a small number of nuclear spins
• Spin decoherence in graphene quantum dots due to hyperfine interaction
• SU(12) Kondo Effect in Carbon Nanotube Quantum Dot
• FCS of superconducting tunnel junctions in non-equilibrium