Bollweg, Kurth, Heitmann, and Gudmundsson Reply:

Bollweg, K.; Kurth, T.; Heitmann, D.; Guðmundsson, Viðar

doi:10.1103/physrevlett.77.2594

Cited by 9 publications

(23 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is not explicitly shown in the figures. Secondly, the negative B dispersion branch of the spin mode manifests a clear oscillatory behaviour with ν, similar to that found for the density response [37], also discussed in Ref. [20]: the 'paramagnetic' even ν configurations have softer spin modes than the 'ferromagnetic' odd ν configurations.…”

supporting

confidence: 81%

Spin and density longitudinal response of quantum dots in the time-dependent local-spin-density approximation

et al. 1999

View full text Add to dashboard Cite

The longitudinal dipole response of a quantum dot has been calculated in the far-infrared regime using local-spin-density-functional theory. We have studied the coupling between the collective spin and density modes as a function of the magnetic field. We have found that the spin dipole mode and single-particle excitations have a sizable overlap, and that the magnetoplasmon modes can be excited by the dipole spin operator if the dot is spin polarized. The frequency of the dipole spin edge mode presents an oscillation which is clearly filling factor () related. We have found that the spin dipole mode is especially soft for evenvalues. Results for selected numbers of electrons and confining potentials are discussed.

show abstract

supporting

confidence: 81%

Spin and density longitudinal response of quantum dots in the time-dependent local-spin-density approximation

et al. 1999

View full text Add to dashboard Cite

show abstract

“…This is a joint project between U.S. EPA Region 5, local community activists, and researchers and was initiated by concerns from the community over high concentrations of HAPs in their neighborhoods (121). The project draws upon a variety of data sources, including the Toxics Release Inventory, local emission inventories, and ambient concentrations, which are used to describe local conditions in terms of air quality, health outcomes, and demographic makeup of the communities in the Chicago area.…”

Section: Exposure Assessment In Urban Communitiesmentioning

confidence: 99%

Urban Air Pollution and Health Inequities: A Workshop Report

2001

Environmental Health Perspectives

View full text Add to dashboard Cite

General overview of health effects research.The evidence on the health effects of air pollution has been summarized in a state-of-theart review (8,9) and a recent monograph (10), as well as in two recent U.S. EPA criteria Over the past three decades, an array of legislation with attendant regulations has been implemented to enhance the quality of the environment and thereby improve the public's health. Despite the many beneficial changes that have followed, there remains a disproportionately higher prevalence of harmful environmental exposures, particularly air pollution, for certain populations. These populations most often reside in urban settings, have low socioeconomic status, and include a large proportion of ethnic minorities. The disparities between racial/ethnic minority and/or lowincome populations in cities and the general population in terms of environmental exposures and related health risks have prompted the "environmental justice" or "environmental equity" movement, which strives to create cleaner environments for the most polluted communities. Achieving cleaner environments will require interventions based on scientific data specific to the populations at risk; however, research in this area has been relatively limited. To assess the current scientific information on urban air pollution and its health impacts and to help set the agenda for immediate intervention and future research, the American Lung Association organized an invited workshop on Urban Air Pollution and Health Inequities held 22-24 October 1999 in Washington, DC. This report builds on literature reviews and summarizes the discussions of working groups charged with addressing key areas relevant to air pollution and health effects in urban environments. An overview was provided of the state of the science for health impacts of air pollution and technologies available for air quality monitoring and exposure assessment. The working groups then prioritized research needs to address the knowledge gaps and developed recommendations for community interventions and public policy to begin to remedy the exposure and health inequities.

show abstract

“…This mode, which can be anticipated on general grounds, emerges in simple theoretical models 7 and has been detected experimentally. 4,5 In the low frequency region we find a more complicated collective mode [peak (L) in Fig. 2 (a)] depicted in Fig.…”

mentioning

confidence: 98%

“…3 A main theme in the FIR absorption experiments has been to detect and classify the rich variety of collective modes that occur in these systems. [4][5][6] Along with the experimental work, theorists have addressed the same issues. [7][8][9][10][11][12][13] The main difficulty lies in the fact that while the superlattice is periodic, the Hamiltonian (including a vector potential) is not.…”

mentioning

confidence: 99%

“…Both peaks, (H) and (L), show absorption of light polarized in the direction of the cyclotron resonance in agreement with experiment. 5 The existing theoretical explanation, 7 however, is based on a model with circularly symmetric unit cells and cannot describe the interplay of modes centered at different places of the unit cell. Besides the modes discussed until now the 2DES absorbs energy at a number of other frequencies.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Butterfly-like spectra and collective modes of antidot superlattices in magnetic fields

Anisimovas

Johansson

1999

Phys. Rev. B

View full text Add to dashboard Cite

We calculate the energy band structure for electrons in an external periodic potential combined with a perpendicular magnetic field. Electron-electron interactions are included within a Hartree approximation. The calculated energy spectra display a considerable degree of self-similarity, just as the "Hofstadter butterfly." However, screening affects the butterfly, most importantly the bandwidths oscillate with magnetic field in a characteristic way. We also investigate the dynamic response of the electron system in the far-infrared (FIR) regime. Some of the peaks in the FIR absorption spectra can be interpreted mainly in semiclassical terms, while others originate from inter(sub)band transitions. 73.20.Dx, 73.20.Mf Recent years have witnessed a considerable amount of research effort directed towards understanding of the physics of two-dimensional electron systems (2DES) whose dimensionality is further restricted by man-made periodic potentials and perpendicular magnetic fields. These include quantum dot arrays and antidot superlattices. Concentrating on the latter ones, one distinguishes two principal directions of experimental work: transport studies and far infrared (FIR) spectroscopy. Some of the transport measurements 1,2 have been performed in search of evidence for a self-similar energy spectrum, the so called Hofstadter butterfly. 3 A main theme in the FIR absorption experiments has been to detect and classify the rich variety of collective modes that occur in these systems. [4][5][6] Along with the experimental work, theorists have addressed the same issues. 7-13 The main difficulty lies in the fact that while the superlattice is periodic, the Hamiltonian (including a vector potential) is not. Most recent calculations of superlattice electronic structure have used the Ferrari basis to deal with this matter. 14 We will instead apply ray-group-theoretical techniques 15-18 to effectively reduce the calculational complexity.With this approach, we are able to go beyond earlier calculations. We find the band structure for interacting electrons in general "rational" magnetic fields [i.e., the flux through a unit cell is (L/N )Φ 0 , where Φ 0 is a flux quantum and L, N ∈ Z]. Consequently, we are able to trace even fine-scale features of the butterfly and at the same time study the effects screening has on it. We also explore the FIR response. The resulting spectra are rather rich. Along with absorption peaks caused by collective modes, and known from experiments, 4,5 we find additional ones of mostly quantum-mechanical origin.The antidot superlattice considered here is of simple square symmetry R = n 1 a 1 + n 2 a 2 , with lattice parameter a. The effective one-particle Hamiltonian iswhere the vector potential A = B × r/2 (symmetric gauge) describes the perpendicular magnetic field B and G = g 1 b 1 + g 2 b 2 , denotes the reciprocal lattice vectors. We use GaAs parameters and work with shortperiod superlattices with a = 1000Å and electron density n s = 1.2 · 10 11 cm −2 . A typical magnetic field B = 1.65 T ...

show abstract

Bollweg, Kurth, Heitmann, and Gudmundsson Reply:

Cited by 9 publications

References 2 publications

Spin and density longitudinal response of quantum dots in the time-dependent local-spin-density approximation

Spin and density longitudinal response of quantum dots in the time-dependent local-spin-density approximation

Urban Air Pollution and Health Inequities: A Workshop Report

Butterfly-like spectra and collective modes of antidot superlattices in magnetic fields

Contact Info

Product

Resources

About