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Singlet-Triplet Transition in lateral Quantum Dots: A Numerical Renormalization Group Study

W. Hofstetter·G. Zarand
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Abstract

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 non-monotonic 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.

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W. Hofstetter, G. Zarand. 2003-06-16. Singlet-Triplet Transition in lateral Quantum Dots: A Numerical Renormalization Group Study. https://doi.org/10.1103/physrevb.69.235301

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