Electronic properties of coupled quantum rings in the presence of a magnetic field

Fuster, G.; Pacheco, M.; Barticevic, Z.

doi:10.1590/s0103-97332004000400037

Cited by 16 publications

(15 citation statements)

References 4 publications

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“…3,4 The same occurs in our present calculations, where most Kohn-Sham orbitals localize to a great extent in either the inner or the outer ring. Therefore, for simplicity throughout this paper we will adopt a fuzzy logic language and classify the DQR states into inner and outer ring states, the criterium for such classification being the charge density maximum localization.…”

Section: Theoretical Considerationssupporting

confidence: 86%

“…5 It does not seem to be the case for self-assembled DQRs. 3,4 Figure 3 represents the independent particle addition energy spectra…”

Section: Resultsmentioning

confidence: 99%

“…Photoluminescence spectra of concentric double quantum rings ͑DQRs͒ were measured and interpreted as evidence of exciton localization in either the inner or the outer ring. 1,2 The single-electron 3,4 and electron-hole 4 energy levels in a magnetic field were studied theoretically and it was shown that, even for small inter-ring distances, self-assembled DQRs could be approximately described as a sum of two decoupled rings. Szafran and Peeters also investigated the magnetic response of one-to three-electron energy levels in DQR structures.…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure of few-electron concentric double quantum rings

et al. 2006

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The ground state structure of few-electron concentric double quantum rings is investigated within the local spin density approximation. Signatures of inter-ring coupling in the addition energy spectrum are identified and discussed. We show that the electronic configurations in these structures can be greatly modulated by the inter-ring distance: At short and long distances the low-lying electron states localize in the inner and outer rings, respectively, and the energy structure is essentially that of an isolated single quantum ring. However, at intermediate distances the electron states localized in the inner and the outer ring become quasidegenerate and a rather entangled, strongly-correlated system is formed.

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Section: Theoretical Considerationssupporting

confidence: 86%

“…5 It does not seem to be the case for self-assembled DQRs. 3,4 Figure 3 represents the independent particle addition energy spectra…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electronic structure of few-electron concentric double quantum rings

et al. 2006

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“…Progress in nanofabrication technology has allowed one to produce self-assembled, strain-free, nanometer-sized quantum complexes consisting of two concentric, welldefined GaAs/ AlGaAs rings 1,2 whose theoretical study has recently attracted some interest. [3][4][5][6] Most of these works are concerned with the properties of their ground state, although the optical properties of one-and two-electron concentric double quantum rings ͑CDQR͒ at zero magnetic field have been addressed using a single-band effective-mass envelope model discarding Coulomb correlation effects. 2 The singular geometry of CDQR has been found to introduce characteristic features in the addition spectrum compared to that of other coupled nanoscopic quantum structures.…”

Section: Ll Serramentioning

confidence: 99%

Optical response of two-dimensional few-electron concentric double quantum rings: A local-spin-density-functional theory study

et al. 2006

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We have investigated the dipole charge-and spin-density response of few-electron two-dimensional concentric nanorings as a function of the intensity of a perpendicularly applied magnetic field. We show that the dipole response displays signatures associated with the localization of electron states in the inner and outer ring favored by the perpendicularly applied magnetic field. Electron localization produces a more fragmented spectrum due to the appearance of additional edge excitations in the inner and outer ring. DOI: 10.1103/PhysRevB.74.193309 PACS number͑s͒: 73.21.Ϫb, 73.22.Ϫf, 71.15.Mb Progress in nanofabrication technology has allowed one to produce self-assembled, strain-free, nanometer-sized quantum complexes consisting of two concentric, welldefined GaAs/ AlGaAs rings 1,2 whose theoretical study has recently attracted some interest.3-6 Most of these works are concerned with the properties of their ground state, although the optical properties of one-and two-electron concentric double quantum rings ͑CDQR͒ at zero magnetic field have been addressed using a single-band effective-mass envelope model discarding Coulomb correlation effects. 2The singular geometry of CDQR has been found to introduce characteristic features in the addition spectrum compared to that of other coupled nanoscopic quantum structures. As a function of the interring distance, the localization of the electrons in either ring follows from the interplay between confining, Coulomb, and centrifugal energies. Each of them prevail in a different range of interring distances, affecting in a different way the CDQR addition spectrum. 6 It is thus quite natural to investigate whether and how localization effects may show up in the dipole response, using a perpendicularly applied magnetic field instead of the interring distance to control the electron localization in either ring.The aim of this paper is to use local-spin-densityfunctional theory ͑LSDFT͒ as described in detail in Ref. 7, to investigate the dipole longitudinal response of CDQR. The method has been used in the past to address the response of single quantum rings ͑see, e.g., Ref. 8 and references therein͒. We address here the few-electron case, and consider the CDQR's as strictly two-dimensional systems.Within LSDFT, the ground state of the system is obtained by solving the Kohn-Sham ͑KS͒ equations. The problem is simplified by the imposed circular symmetry around the z axis, which allows one to write the single particle ͑sp͒ wave functions as nl ͑r , ͒ = u nl ͑r͒e −ıl , being −l the projection of the sp orbital angular momentum on the z axis. The confining potential has been taken in a form that slightly generalizes that of Ref. 4,with R 1 = 20 nm, R 2 = 40 nm, 1 = 30 meV, and 2 = 40 meV. The radii have been fixed to the experimental values, 2 while the frequencies are rather arbitrary. We have considered large frequencies to mimic the strong confinement felt by the CDQR, and have taken 2 Ͼ 1 to somewhat compensate that, as R 2 Ͼ ϾR 1 , the "surface" of the outer ring might hav...

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“…More recently, progress in nanofabrication has allowed to produce nanometer-sized quantum complexes consisting of two concentric, GaAs/AlGaAs rings [5][6][7][8], whose theoretical study has drawn some interest [9][10][11][12][13][14][15]. The particular geometry of these concentric double quantum rings (CDQR) is at the root of the appearance of electron localization processes, mostly of radial nature, whose existence has been predicted within local spin-density functional (LSDF) theory [13], by exact diagonalization of the CDQR configuration interaction Hamiltonian [10,15], and by quantum Monte Carlo calculations [14].…”

Section: Introductionmentioning

confidence: 99%