We theoretically study an enhancement of the Kondo effect in quantum dots with two orbitals and spin 12. The Kondo temperature and conductance are evaluated as functions of energy difference Δ between the orbitals, using the numerical renormalization group method. The Kondo temperature is maximal around the degeneracy point (Δ=0) and decreases with increasing |Δ| following a power law, TK(Δ)=TK(0)(TK(0)/|Δ|)γ, which is consistent with the scaling analysis. The conductance at T=0 is almost constant 2e2/h. Both the orbitals contribute to the conductance around Δ=0, whereas the current through the upper orbital is negligibly small when |Δ|≳TK(0). These are characteristics of SU(4) Kondo effect.
|ジャーナル||Physica E: Low-Dimensional Systems and Nanostructures|
|出版ステータス||Published - 2005 11 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics