Evidence of Correlation in Spin Excitations of Few-Electron Quantum Dots

Abstract

We report inelastic light scattering measurements of spin and charge excitations in nanofabricated AlGaAs/GaAs quantum dots with few electrons. A narrow spin excitation peak is observed and assigned to the intershell triplet-to-singlet monopole mode of dots with four electrons. Configuration-interaction theory provides precise quantitative interpretations that uncover large correlation effects that are comparable to exchange Coulomb interactions.

Full configuration interaction approach to the few-electron problem in artificial atoms

“…Moreover, many experimental techniques allow nowadays to access QD excitation spectrum, such as single-electron non-linear tunneling experiments, 13,122 far-infrared spctroscopy, 1 inelastic light scattering. 12 In addition, the theoretical analysis of the energy spectrum gives a precious insight into QD physics. Figure 9 displays our FCI results for the low-energy region of the excitation spectrum of a six-electron quantum dot in the Wigner regime (λ = 8), for different values of the total orbital angular momentum and spin multiplicities.…”

“…With those and similar tricks all types of matrix elements are easily evaluated. The above procedure is especially advantageous for post-processing, 9,12,13,14,15,63,64,65,66,67,109 since the evalutation of various matrix elements is particularly transparent and simple once physical operators are expressed in their second quantized form.…”

“…5,6,7,8,9 Shell structure 7,8,10 and correlation effects 9,11,12 are among the most striking experimental demonstrations. More recently, the interest in new classes of devices has fuelled investigations of QDs which are coupled by quantum tunneling.…”

Theory of Electron Spectroscopies in Strongly Correlated Semiconductor Quantum Dots

“…3, this trivial effect should be totally compensated. However, rontani Instructions for Typing Manuscripts (Paper's Title) 9 we see for λ = 10 (n e ≈ 1.1 × 10 9 cm −2 ) that the now much stronger correlation is responsible for an unexpected weight reorganization, which is related to the formation of a "ring" of crystallized electrons in the Wigner molecule (cf. Sec.…”

“…3,4,5,6,7 Shell structure, 5,6,8 correlation effects, 9 Kondo physics, 10,11 are among the most striking experimental demonstrations. An intriguing feature of these artificial atoms is the possibility of a fine control of a variety of parameters in the laboratory.…”