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

References in corpus (7)

• Kondo effect in quantum dots coupled to ferromagnetic leads
• Electric-field controlled spin reversal in a quantum dot with ferromagnetic contacts
• Electronic excitations of a single molecule contacted in a three-terminal configuration
• Gate-controlled spin-splitting in quantum dots with ferromagnetic leads in the Kondo regime
• Transport spectroscopy of Kondo quantum dots coupled by RKKY interaction
• Kondo effect in coupled quantum dots with RKKY interaction: Finite temperature and magnetic field effects
• Single Spin Detection with a Carbon Nanotube Double Quantum Dot