SingletTriplet Transition in lateral Quantum Dots A Numerical Renormalization Group Study.pdfVIP

Singlet–Triplet Transition in lateral Quantum Dots: A Numerical Renormalization Group Study W. Hofstetter1, ∗ and G. Zarand2, 1, † 1Lyman Laboratory, Harvard University, Cambridge, MA 02138, USA 3 2 Theoretical Physics Department, Budapest University of Technology and Economics, Budafoki ut´ 8. H-1521 Hungary 0 0 We discuss transport through a lateral quantum dot in the vicinity of a singlet-triplet spin transi- 2 tion 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 n field and the splitting of the singlet and triplet states. We find reduced low-energy transport, and a u non-monotonic magnetic field dependence both in the singlet and the triplet regime. For a generic J set of dot parameters and no Zeeman splitting, the singlet-triplet transition may be identified with 6 the conductance maximum. The conductance is least sensitive to the magnetic field in the region 1 of the transition, where it decreases upon application of a magnetic field. Our results are in good agreement with recent experimental data. ] l l a h I. INTRODUCTION the conductance by applying the Landauer-B¨uttiker for- - mula. Our calculations are in good agreement with ex- s Recent observations of the Kondo effect in semicon- periments and reproduce the