We discuss transport through a lateral quantum dot in the vicinity of a singlet-triplet spin transition in its ground state. Extracting the scattering phase shifts from the numerical renormalization group spectra, we determine the linear conductance at zero temperature as a function of a Zeeman field and the splitting of the singlet and triplet states. We find reduced low-energy transport, and a nonmonotonic magnetic-field dependence both in the singlet and the triplet regime. For a generic set of dot parameters and no Zeeman splitting, the singlet-triplet transition may be identified with the conductance maximum. The conductance is least sensitive to the magnetic field in the region of the transition, where it decreases upon application of a magnetic field. Our results are in good agreement with recent experimental data.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Jun 1 2004|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics