Vertically coupled quantum dots in the local spin-density functional theory

Vertically coupled quantum dots in the local spin-density functional theory

We have investigated the structure of double quantum dots vertically coupled at zero magnetic field within local-spin-density functional theory. The dots are identical and have a finite width, and the whole system is axially symmetric. We first discuss the effect of thickness on the addition spectrum of one single dot. Next we describe the structure of coupled dots as a function of the interdot...

Spin interactions and switching in vertically tunnel-coupled quantum dots

We determine the spin-exchange coupling J between two electrons located in two vertically tunnel-coupled quantum dots, and its variation when magnetic ~B! and electric ~E! fields ~both in-plane and perpendicular! are applied. We predict a strong decrease of J as the in-plane B field is increased, mainly due to orbital compression. Combined with the Zeeman splitting, this leads to a singlet-trip...

Density Functional Theory of Spin-Polarized Disordered Quantum Dots

Using density functional theory, we investigate fluctuations of the ground-state energy of spin-polarized, disordered quantum dots in the metallic regime. To compare to experiment, we evaluate the distribution of addition energies and find a convolution of the Wigner-Dyson distribution, expected for noninteracting electrons, with a narrower Gaussian distribution due to interactions. The third m...

Spin-Density-Functional Theory of Circular and Elliptical Quantum Dots

Using spin-density-functional theory, we study the electronic states of a two-dimensional parabolic quantum dot with up to N = 58 electrons. We observe a shell structure for the filling of the dot with electrons. Hund’s rule determines the spin configuration of the ground state, but only up to 22 electrons. At specific N , the ground state is degenerate, and a small elliptical deformation of th...

Optical anisotropy in vertically coupled quantum dots