Effects of Electron-Electron Scattering in Wide Ballistic Microcontacts

Nagaev, K. É.; Ayvazyan, O. S.

doi:10.1103/physrevlett.101.216807

Cited by 22 publications

(52 citation statements)

References 15 publications

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“…This situation was analyzed in Ref. [27] perturbatively in the ee scattering rate, finding a conductance enhacement that resembles our results.…”

Section: )supporting

confidence: 84%

“…Evaluating the integral over k 2 in Eq. (25) we obtain D ss (k) = π 2 sgn κ + κ + (κ 2 + 1) cot −1 κ πκv (27) where κ = kv/γ. This expression defines an even function of k with the asymptotics…”

Section: )mentioning

confidence: 93%

“…We note parenthetically that discretization has no impact on the values D ss (k 1 = 0) given in Eqs. (27), (28). We obtain current distribution by solving numerically Eq.…”

Section: )mentioning

confidence: 99%

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Higher-than-ballistic conduction of viscous electron flows

Guo

Ilseven

Falkovich

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

217

215

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Strongly interacting electrons can move in a neatly coordinated way, reminiscent of the movement of viscous fluids. Here, we show that in viscous flows, interactions facilitate transport, allowing conductance to exceed the fundamental Landauer's ballistic limit G ball . The effect is particularly striking for the flow through a viscous point contact, a constriction exhibiting the quantum mechanical ballistic transport at T = 0 but governed by electron hydrodynamics at elevated temperatures. We develop a theory of the ballistic-to-viscous crossover using an approach based on quasi-hydrodynamic variables. Conductance is found to obey an additive relation G = G ball + G vis , where the viscous contribution G vis dominates over G ball in the hydrodynamic limit. The superballistic, low-dissipation transport is a generic feature of viscous electronics.electron hydrodynamics | graphene | strongly correlated systems F ree electron flow through constrictions in metals is often regarded as an ultimate high-conduction charge transfer mechanism (1-5). Can conductance ever exceed the ballistic limit value? Here we show that superballistic conduction is possible for strongly interacting systems in which electron movement resembles that of viscous fluids. Electron fluids are predicted to occur in quantum-critical systems and in high-mobility conductors, so long as momentum-conserving electron-electron (ee) scattering dominates over other scattering processes (6-9). Viscous electron flows feature a host of novel transport behaviors (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Signatures of such flows have been observed in ultraclean GaAs, graphene, and ultrapure PdCoO2 (23-26).We will see that electrons in a viscous flow can achieve through cooperation what they cannot accomplish individually. As a result, resistance and dissipation of a viscous flow can be markedly smaller than that for the free-fermion transport. As a simplest realization, we discuss viscous point contact (VPC), where correlations act as a "lubricant" facilitating the flow. The reduction in resistance arises due to the streaming effect illustrated in Fig. 1, wherein electron currents bundle up to form streams that bypass the boundaries, where momentum loss occurs. This surprising behavior is in a clear departure from the common view that regards electron interactions as an impediment for transport.A simplest VPC is a 2D constriction pictured in Fig. 1A. The interaction effects dominate in constrictions of width w exceeding the carrier collision mean free path lee (and much greater than the Fermi wavelength λF ). The VPC conductance, evaluated in the absence of impurity scattering, scales as a square of the width w and inversely with the electron viscosity η,where n and e are the carrier density and charge. In the opposite limit, lee w , the ballistic free-fermion model (1, 5) predicts the conductance G ball = 2e 2 /h N , where N ≈ 2w /λF is the number of Landauer's open transmission channels. The conductance G vis grows with width faster than G ball ...

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“…This situation was analyzed in Ref. [27] perturbatively in the ee scattering rate, finding a conductance enhacement that resembles our results.…”

Section: )supporting

confidence: 84%

Section: )mentioning

confidence: 93%

See 1 more Smart Citation

Higher-than-ballistic conduction of viscous electron flows

Guo

Ilseven

Falkovich

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

217

215

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show abstract

“…A similar decrease of resistance was obtained later for 2D constrictions with viscous electron flow [5], where the electron-electron scattering serves as a "lubricant" for the rough boundaries of the conducting area. The electron-electron scattering results in the decrease of the resistance even for contacts with smooth boundaries because it changes the trajectories of electrons and may prevent them from passing through the constriction or help them to get through it [6,7]. This decrease was experimentally observed in several papers [8,9].…”

Section: Introductionmentioning

confidence: 99%

Electron-electron scattering and conductance of long many-mode channels

Nagaev

2018

Physica E: Low-dimensional Systems and Nanostructures

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The electron-electron scattering increases the resistance of ballistic many-mode channels whose width is smaller than their length. We show that this increase saturates in the limit of infinitely long channels. Because the mechanisms of angular relaxation of electrons in three and two dimensions are different, the saturation value of the correction to the resistance is temperature-independent in the case of three-dimensional channels and is proportional to the temperature for two-dimensional ones. The spatial behavior of electron distribution in the latter case is described by an unusual characteristic length.

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“…The small T 3 factor is due to the small difference of the two initial or final wave vectors in Eq. (9). A wealth of transitions contributing to the current is available at µ = µ b ≈ 0 that coincides with the crossing point of the + and -branches of the spectrum.…”

mentioning

confidence: 95%

Spin-orbit coupling and resonances in the conductance of quantum wires

Khrapai

Nagaev

2018

Phys. Rev. B

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We investigate a possibility of pair electron-electron (e-e) collisions in a ballistic wire with spinorbit coupling and only one populated mode. Unlike in a spin-degenerate system, a combination of spin-splitting in momentum space with a momentum-dependent spin-precession opens up a finite phase space for pair e-e collisions around three distinct positions of the wire's chemical potential. For a short wire, we calculate corresponding resonant contributions to the conductance, which have different power-law temperature dependencies, and, in some cases, vanish if the wire's transverse confinement potential is symmetric. Our results may explain the recently observed feature at the lower conductance plateau in InAs wires.

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Effects of Electron-Electron Scattering in Wide Ballistic Microcontacts

Cited by 22 publications

References 15 publications

Higher-than-ballistic conduction of viscous electron flows

Higher-than-ballistic conduction of viscous electron flows

Electron-electron scattering and conductance of long many-mode channels

Spin-orbit coupling and resonances in the conductance of quantum wires

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