Anisotropic plasmon dispersion in a lateral quantum-wire superlattice

Egeler, T.; Abstreiter, G.; Weimann, G.; Demel, T.; Heitmann, D.; Grambow, P.; Schlapp, W.

doi:10.1103/physrevlett.65.1804

Cited by 114 publications

(33 citation statements)

References 14 publications

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“…There are also very interesting Raman experiments on quantum wires and dots. [6][7][8][9][10][11][12][13] Strenz et al reported on SPE in quantum wires and observed SPE in dots. 11 Onedimensional electron systems which are nearly in the 1D quantum limit have been investigated by Schmeller et al 9 They found that the relative energy renormalizations of the 1D intersubband SDE and CDE with respect to the simultaneously observed corresponding SPE are quite similar to those found for 2D systems.…”

Section: P Grambow and K Eberlmentioning

confidence: 96%

Single-particle excitations and many-particle interactions in quantum wires and dots

et al. 1996

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We have investigated electronic excitations in GaAs-Al x Ga 1Ϫx As quantum wires, and dots by resonance Raman spectroscopy. We find for quantum dots and quantum wires three types of excitations; single-particle, spin-density, and charge-density excitations ͑SPE's, SDE's, and CDE's, respectively͒. Our experiments show that SPE's are enhanced under conditions of extreme resonance, which indicates that energy-density fluctuations are responsible for the excitation of unscreened SPE's. The high intensity of the SPE's allows a detailed analysis of collective effects in the zero-and one-dimensional electron systems. ͓S0163-1829͑96͒51848-5͔In high-quality modulation-doped GaAs-Al x Ga 1Ϫx As heterostructures nearly perfect two-dimensional ͑2D͒ electron systems with quantized energy levels can be realized. With sophisticated technology it is possible to produce lateral structures and reduce the dimensionality even further and fabricate one-dimensional ͑1D͒ quantum wires and zerodimensional ͑0D͒ quantum dots, the latter with a totally discrete energy spectrum. 1 These systems have attracted great interest since they allow, in specially tailored structures, a detailed investigation of quantum and, in particular, manybody effects. Raman spectroscopy is an ideal tool to study these many-body effects since, with polarization-dependent selection rules, one can map out different many-body effects. 2 For a parallel polarization of incoming and Ramanscattered photons one measures so called charge-density excitations ͑CDE's͒, which reflect the collective excited states of the electron system and which are renormalized due to the dynamic charge and spin redistribution. In highly symmetric systems CDE's are the only excitations observed in direct far-infrared absorption. 1 In Raman spectroscopy one can additionally measure in crossed polarization collective spindensity excitations, which are affected only by the dynamic spin redistribution. It was very surprising with respect to the so far accepted theory 3 that Pinczuk et al. 4 observed on high-quality two-dimensional systems, in addition to CDE's and SDE's, an excitation that exhibited all features of an unrenormalized single-particle excitation. This excitation is observed in both polarizations. These results have been confirmed by a number of authors 5 -we see it in our 2D samples, too-however, the scattering mechanism was so far not clear. There are also very interesting Raman experiments on quantum wires and dots. 6-13 Strenz et al. reported on SPE in quantum wires and observed SPE in dots. 11 Onedimensional electron systems which are nearly in the 1D quantum limit have been investigated by Schmeller et al. 9 They found that the relative energy renormalizations of the 1D intersubband SDE and CDE with respect to the simultaneously observed corresponding SPE are quite similar to those found for 2D systems. 4 However, the mechanism and conditions for the excitation and strength of collective effects for quantum dots and wires are even less clear. Very recently, an interesting pap...

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Section: P Grambow and K Eberlmentioning

confidence: 96%

Single-particle excitations and many-particle interactions in quantum wires and dots

et al. 1996

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“…Figure 4 shows the calculated current densities j (x) for the two lowest modes at three different gate voltages. Peak ͑2͒ associated with j (2) (x) ͑dashed lines͒ is the interwire resonance of the coupled wire system ͓ j (2) (x) has no node͔, whereas peak ͑1͒ associated with j (1) (x) ͑solid lines͒ is the intrawire resonance of the individual channels ͓ j (1) (x) has two nodes near the boundaries between the channels and the middle region͔. With increasing electron density n 2 , mode ͑1͒ assumes the character of the first dipole-active harmonic of the wide wire formed by the entire system.…”

Section: ͑4͒mentioning

confidence: 99%

“…Interactions between semiconductor nanostructures such as quantum wires [1][2][3][4] and quantum dots 5 are subject to current intensive research. Previous work has focused on Coulomb coupling 1-3 and tunneling.…”

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confidence: 99%

Magnetoplasmon mode in connected quantum-wire pairs

et al. 1997

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We study the magnetoplasma excitations of field-effect-induced quantum-wire lattices with a unit cell that contains two closely spaced electron channels. The far-infrared-transmission spectra contain an additional mode that is not present in lattices with a simple unit cell investigated previously. We show with a classical model as well as by quantum-mechanical calculations that this mode can be explained by an interwire motion of the electrons that is characteristic for the double-wire system.

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“…Another way to probe the electron gas is through optical measurements. A number of reports have been devoted to the probing of quasi-2DEG and quasi-1DEG energy spectrum using different techniques such as Fourier transform infrared spectroscopy ͑FTIR͒, [36][37][38][39][40][41][42][43][44][45][46][47][48] Raman scattering spectroscopy, [49][50][51][52][53][54][55][56][57] far-infrared ͑FIR͒ laser spectroscopy [58][59][60] and photoluminescence. [61][62][63][64][65][66][67][68][69][70] In all these techniques a collective excitation of the 1DEG is measured, the Raman scattering also giving information about single particle excitations.…”

Section: Introductionmentioning

confidence: 99%

Electrical transport and far-infrared transmission in a quantum wire array

Lefebvre

Beerens

Feng

et al. 1998

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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A wide set of data obtained on a two-dimensional electron gas submitted to a tunable lateral modulation, induced using a split-gate technique, is presented. Owing to a unique design of the sample, it has been possible to combine in a single experimental run, far-infrared transmission measurements and electrical transport measurements in both directions parallel and perpendicular to the lateral modulation. The discussion of the results emphasizes the correspondence between various features observed in both types of measurements. Based on these features, three regimes of modulation are clearly identified, namely the weak, intermediate and strong modulation regimes. Far-infrared transmission data show that each of these regimes is characterized by plasmon modes with a distinctive behavior. These behaviors are analyzed further with the use of transport data, which allow to determine the electron concentration in the structure for every condition of gate voltage. In the weak modulation regime, a quantitative analysis shows that the collective mode energy is consistent with that of a classical 2D plasmon at q=2π/a (where a is the period of the split gate), using the average electron concentration under the gate as the relevant parameter. In the intermediate regime, the collective modes are confined plasmons. The observation of “confined Bernstein modes” indicates that the bare confinement potential is nonparabolic in this regime. In the strong modulation regime, the observation of a far-infrared resonance energy which does not depend on the modulation amplitude, while the effective 2D electron concentration (within each wire) varies with gate voltage, shows that the collective mode is a Kohn mode.

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Anisotropic plasmon dispersion in a lateral quantum-wire superlattice

Cited by 114 publications

References 14 publications

Single-particle excitations and many-particle interactions in quantum wires and dots

Single-particle excitations and many-particle interactions in quantum wires and dots

Magnetoplasmon mode in connected quantum-wire pairs

Electrical transport and far-infrared transmission in a quantum wire array

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