Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 49: Poster II

HL 49.35: Poster

Donnerstag, 27. März 2003, 16:30–19:00, HSZ/P2

Theory of the spin singlet electronic droplet in a lateral quantum dot — •Andreas Wensauer¹, Marek Korkusinski², and Pawel Hawrylak² — ¹Institute for Theoretical Physics, University of Regensburg — ²Institute for Microstructural Sciences, National Research Council Canada

We present results of Density-Functional Theory calculations of the electronic properties of the spin singlet electronic droplet at filling factor ν = 2 in a lateral quantum dot as a function of the magnetic field B and the number of electrons N. The stability of the spin singlet droplet at high magnetic fields is determined by the spin flip excitation localized at the edge of the droplet. The stability at low magnetic fields is determined by a spin flip excitation involving one electron at the edge and one electron in the center of the droplet. We show that the spin singlet droplet vanishes at a critical number of electrons N_c. Above this critical number the even electron droplet evolves directly from a spin triplet state with one electron in the center and one in the edge to a state with spin polarized edge. We discuss how these spin transitions for even electron numbers combined with spin transitions for odd electron numbers manifest themselves in the addition and amplitude spectrum of a quantum dot in transport experiments. The results of our calculations are compared with recent experiments.

Reference: Ciorga, Wensauer, et al., PRL 88, 256804 (2002)