Saturation of electron phase breaking time in GaAs/AlGaAs quantum wires

Noguchi, M.; Ikoma, Toshiaki; Odagiri, Takahide; Sakakibara, H.; Wang, Shi Nan

doi:10.1063/1.363495

Cited by 24 publications

(24 citation statements)

References 20 publications

(20 reference statements)

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“…From figure 42, it is apparent that the saturated value of the dephasing time increases with increasing mobility (that is, with increasing spacer-layer thickness), a trend that was also noted in the study by Bird et al [122]. In figure 44, the variation of the saturated dephasing time with mobility is summarized for both ion-beam implanted and split-gate wires [229]. While there is clearly a consistent difference between the two types of wire, we see from this figure that the saturated value of τ φ scales approximately with mobility as τ φ ∝ µ (for high-mobility samples).…”

Section: Dephasing In Dirty and Quasi-ballistic Quantum Wiressupporting

confidence: 66%

“…polycrystalline) structure, while it might not be universal over different dimensionalities and different sample structures. On the contrary, it is often conjectured that τ 0 φ should increase with reducing disorder, at least in one and two dimensions [12,229]. Until now, it has not been known exactly how differently τ 0 φ should behave in different dimensionalities and in different sample structures.…”

Section: Systematic Measurements and Indications Of Non-magnetic Originmentioning

confidence: 99%

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Recent experimental studies of electron dephasing in metal and semiconductor mesoscopic structures

Lin

Bird

2002

J. Phys.: Condens. Matter

363

417

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In this review, we discuss the results of recent experimental studies of the low-temperature electron dephasing time (τ φ) in metal and semiconductor mesoscopic structures. A major focus of this review is on the use of weak localization, and other quantum-interference-related phenomena, to determine the value of τ φ in systems of different dimensionality and with different levels of disorder. Significant attention is devoted to a discussion of three-dimensional metal films, in which dephasing is found to predominantly arise from the influence of electron-phonon (e-ph) scattering. Both the temperature and electron mean free path dependences of τ φ that result from this scattering mechanism are found to be sensitive to the microscopic quality and degree of disorder in the sample. The results of these studies are compared with the predictions of recent theories for the e-ph interaction. We conclude that, in spite of progress in the theory for this scattering mechanism, our understanding of the e-ph interaction remains incomplete. We also discuss the origins of decoherence in low-diffusivity metal films, close to the metal-insulator transition, in which evidence for a crossover of the inelastic scattering, from e-ph to 'critical' electron-electron (e-e) scattering, is observed. Electronelectron scattering is also found to be the dominant source of dephasing in experimental studies of semiconductor quantum wires, in which the effects of both large-and small-energy-transfer scattering must be taken into account. The latter, Nyquist, mechanism is the stronger effect at a few kelvins, and may be viewed as arising from fluctuations in the electromagnetic background, generated by the thermal motion of electrons. At higher temperatures, however, a crossover to inelastic e-e scattering typically occurs; and evidence for this large-energy-transfer process has been found at temperatures as high as 30 K. Electron-electron interactions are also thought to play an important role in dephasing in ballistic quantum dots, and the results of recent experiments in this area are reviewed. A common feature of experiments, in both dirty metals

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Section: Dephasing In Dirty and Quasi-ballistic Quantum Wiressupporting

confidence: 66%

Section: Systematic Measurements and Indications Of Non-magnetic Originmentioning

confidence: 99%

Recent experimental studies of electron dephasing in metal and semiconductor mesoscopic structures

Lin

Bird

2002

J. Phys.: Condens. Matter

363

417

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“…Some attempts to measure the D dependence of have been performed in metallic systems 2,22 as well as in semiconductor ones. 23 However, any clear conclusion could not be drawn from those experiments since it is difficult to vary D in a controlled way over a wide range.…”

Section: Introductionmentioning

confidence: 99%

Quantum coherence at low temperatures in mesoscopic systems: Effect of disorder

et al. 2010

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We study the disorder dependence of the phase coherence time of quasi-one-dimensional wires and twodimensional ͑2D͒ Hall bars fabricated from a high mobility GaAs/AlGaAs heterostructure. Using an original ion implantation technique, we can tune the intrinsic disorder felt by the 2D electron gas and continuously vary the system from the semiballistic regime to the localized one. In the diffusive regime, the phase coherence time follows a power law as a function of diffusion coefficient as expected in the Fermi-liquid theory, without any sign of low-temperature saturation. Surprisingly, in the semiballistic regime, it becomes independent of the diffusion coefficient. In the strongly localized regime we find a diverging phase coherence time with decreasing temperature, however, with a smaller exponent compared to the weakly localized regime.

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“…2, for all the investigated samples, L ðTÞ is described very well by Eq. (3), where a is treated as a fitting parameter (a exp ), and adding an extra term / T À1 for ''high'' energy processes [16]. We can go further in the analysis by looking at the L dependence as a function of D. Let us remind that the diffusion coefficient reflects the strength of the electronelectron interaction [1,19] and thus controls the lowtemperature behavior of the dephasing rate.…”

mentioning

confidence: 99%

Effect of Disorder on the Quantum Coherence in Mesoscopic Wires

et al. 2009

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We present phase coherence time measurements in quasi-one-dimensional mesoscopic wires made from high mobility two-dimensional electron gas. By implanting gallium ions into a GaAs/AlGaAs heterojunction we are able to vary the diffusion coefficient over 2 orders of magnitude. We show that in the diffusive limit, the decoherence time follows a power law as a function of diffusion coefficient as expected by theory. When the disorder is low enough so that the samples are semiballistic, we observe a new and unexpected regime in which the phase coherence time is independent of disorder. In addition, for all samples the temperature dependence of the phase coherence time follows a power law down to the lowest temperatures without any sign of saturation and this strongly suggests that the frequently observed low temperature saturation is not intrinsic.

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Saturation of electron phase breaking time in GaAs/AlGaAs quantum wires

Cited by 24 publications

References 20 publications

Recent experimental studies of electron dephasing in metal and semiconductor mesoscopic structures

Recent experimental studies of electron dephasing in metal and semiconductor mesoscopic structures

Quantum coherence at low temperatures in mesoscopic systems: Effect of disorder

Effect of Disorder on the Quantum Coherence in Mesoscopic Wires

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