Anomalous conductance quantization in the inter-band gap of a one-dimensional channel

Green, Frederick; Das, Mukunda P.

doi:10.1088/1361-648x/aadafd

Cited by 3 publications

(11 citation statements)

References 21 publications

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“…One can compare the results of our calculation in figure 2 [17] with the experimental data in figure 1. While the calculated conductances overestimate the measured step values in our simplified simulation, the robust character of the plateaux and their voltage dependence are strikingly similar to experiment.…”

Section: Interacting One-dimensional Bandsmentioning

confidence: 86%

“…This shows that effects beyond simple quantum-coherent transmission dominate the transport physics. Adapted from [17]. © IOP Publishing Ltd.…”

Section: Interacting One-dimensional Bandsmentioning

confidence: 99%

“…The calculation involves solving a coupled quantum Boltzmann equation including a generation-recombination mechanism induced by the interband transition rate. Here we set out the schematics of the procedure; for details see [17]. We restrict the problem to two channels separated by a given band gap E g .…”

Section: Interacting One-dimensional Bandsmentioning

confidence: 99%

“…This is responsible for the strong enhancement of the step in G, beyond the upper bound posited by quantum-transmission models of conductance. Adapted from [17]. © IOP Publishing Ltd.…”

Section: Interacting One-dimensional Bandsmentioning

confidence: 99%

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Normal and `Anomalous' in Nonlinear Quantum Conductance for Mesoscopic Systems

Das,

Green

2022

Preprint

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Practical mesoscopic devices must function at operating points involving large internal driving fields. Experimental evidence has long accumulated that certain apparently anomalous nonlinear features of quantum transport lie beyond the descriptive capacity of accepted models. We review the physical setting for these anomalous effects and suggest how microscopically argued quantum kinetic descriptions can overcome the predictive limitations of standard theories of quantized resistance. I. INTRODUCTIONPhenomena in quantum transport unique to two-dimensionally constrained electronic systems, formerly considered exotic, have since become bread-and-butter items for condensed-matter physics. Already for some time, in the form of quantum-well-confined structures, they have been deeply embedded in the design even of prosaic consumer electronics.Slightly later than the basic two-dimensional breakthroughs of the 1970s came those at the next level, for structures essentially at one dimension (1D). Their fundamental exploration is very much a current research focus for the physics of electronic transport. While one might argue that their truly large-scale applications have some way to go to outdo the widespread success of their two-dimensional predecessors, it is taken for granted that this is a basic matter of concerted technical development. It is the physical underpinning of the 1D device realm that forms the topic in the following, somewhat condensed, review.We concentrate on aspects of observed 1D transport behaviour that appear to go against accepted theoretical models. Both experimentalists and theorists tend to refer to these laboratory results as "anomalous"; but any consistent departure from experimental expectations will always be perceived as abnormal -until a tenable explanation emerges. The question is: "anomalous" relative to what? The answer is: relative to the received theoretical understanding. Nature entertains no anomalies. It is we as investigators who are subject to a momentary cognitive dissonance. Anomalous results, by their very presence, tell us that more is demanded of a quantitative theory than anything in common currency.Anomalies in nonlinear 1D transport emerged around the turn of this century. The actual surprise, there, is not their discovery but that they seemed to remain in the "too-hard basket", practically unattended to in the literature.Here we review two cases that have now been addressed, and cite a third intriguing instance still defying analysis.Our first example is excess 1D conductance in a working region where the conductance quantum e 2 /πh is supposed never to be exceeded [1,2]; the second is anomalous hot-electron noise in a 1D wire, or quantum point contact (QPC) [3]. The third striking example, which we can discuss only in passing, is the nonlinear Aharanov-Bohm effect [4]. These measurements, largely bypassed by theorists, supply appreciable evidence for reconsidering the limits of accepted mesoscopic transport models [5]. II. BACKGROUNDWe begin by recapitulating the distinc...

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Section: Interacting One-dimensional Bandsmentioning

confidence: 86%

“…This shows that effects beyond simple quantum-coherent transmission dominate the transport physics. Adapted from [17]. © IOP Publishing Ltd.…”

Section: Interacting One-dimensional Bandsmentioning

confidence: 99%

Section: Interacting One-dimensional Bandsmentioning

confidence: 99%

“…This is responsible for the strong enhancement of the step in G, beyond the upper bound posited by quantum-transmission models of conductance. Adapted from [17]. © IOP Publishing Ltd.…”

Section: Interacting One-dimensional Bandsmentioning

confidence: 99%

See 2 more Smart Citations

Normal and `Anomalous' in Nonlinear Quantum Conductance for Mesoscopic Systems

Das,

Green

2022

Preprint

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“…Naïve one-body quantum transmission, however, fails to explain any of the substantial number of further experimental observations now available [13][14][15][16]. Why and how it fails is by now known [17][18][19][20][21]. Coherent transmission is restricted to weak field linear response.…”

Section: Introductionmentioning

confidence: 99%

Anomalies in one-dimensional electron transport: quantum point contacts and wires

Das¹,

Green²

2019

Adv. Nat. Sci: Nanosci. Nanotechnol.

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Over the last several decades, interest in quasi-one dimensional charge transport has progressed from the seminal discoveries of Landauer quantization of conductance as a function of carrier density, to significant finer-scale phenomena. Those include: (i) fractional conductance, or '0.7 anomaly'; (ii) zero-bias anomaly; (iii) Rashba-effect anomalies; and (iv) apparent violation of the Landauer upper bound on conductance. In this work we present a very short summary of the first three items. The last anomaly, which remained theoretically unexamined until recently, is discussed in detail with emphasis on novel low-dimensional physics.

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On Three “Anomalous” Measurements of Nonlinear QPC Conductance

Das

Green

2022

Condensed Matter

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Practical mesoscopic devices based on quantum point contacts (QPCs) must function at operating point involving large internal driving fields. Experimental evidence has accumulated to display anomalous nonlinear features of QPC response beyond the capacities of accepted tunnelling-based models of nonlinear quantum transport. Here, we recall the physical setting of three anomalous QPC experiments and review how, for two of them, a microscopically based nonequilibrium quantum kinetic description—the correct physical boundary conditions being crucial—has already overcome the predictive limitations of standard nonequilibrium mesoscopic models. The third experiment remains a significant challenge to all theorists.

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Anomalous conductance quantization in the inter-band gap of a one-dimensional channel

Cited by 3 publications

References 21 publications

Normal and `Anomalous' in Nonlinear Quantum Conductance for Mesoscopic Systems

Normal and `Anomalous' in Nonlinear Quantum Conductance for Mesoscopic Systems

Anomalies in one-dimensional electron transport: quantum point contacts and wires

On Three “Anomalous” Measurements of Nonlinear QPC Conductance

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