Phase coherent transport in graphene nanoribbons and graphene nanoribbon arrays

Graphene—two-dimensional carbon—is a material with unique mechanical, optical, chemical, and electronic properties. Its use in a wide range of applications was therefore suggested. From an electronic point of view, nanostructured graphene is of great interest due to the potential opening of a band gap, applications in quantum devices, and investigations of physical phenomena. Narrow graphene stripes called “nanoribbons” show clearly different electronical transport properties than micron-sized graphene devices. The conductivity is generally reduced and around the charge neutrality point, the conductance is nearly completely suppressed. While various mechanisms can lead to this observed suppression of conductance, disordered edges resulting in localized charge carriers are likely the main cause in a large number of experiments. Localized charge carriers manifest themselves in transport experiments by the appearance of Coulomb blockade diamonds. This review focuses on the mechanisms responsible for this charge localization, on interpreting the transport details, and on discussing the consequences for physics and applications. Effects such as multiple coupled sites of localized charge, cotunneling processes, and excited states are discussed. Also, different geometries of quantum devices are compared. Finally, an outlook is provided, where open questions are addressed.

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“…56,62,164,173,189,190,195,197,198,200,205,and 214]) and in some of them, quantum Hall effect was observed (see Refs. 62,189,197,198, and 205).…”

Section: Magnetic Fieldmentioning

confidence: 97%

Localized charge carriers in graphene nanodevices

Bischoff

Varlet

Simonet

et al. 2015

Applied Physics Reviews

100

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“…Thus far, a number of papers that discuss the relationship between universal conductance fluctuation (UCF) and WL both experimentally and theoretically have been published [27][28][29][30][31][32][33][34] . In particular, double experimental papers 30,31 using scanning probe microscopy for graphene and transport experiments 15,32 revealed that the dephasing length causing the UCF and WL are of the same order.…”

Section: Introductionmentioning

confidence: 99%

Relationship between conductance fluctuation and weak localization in graphene

et al. 2017

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The relationship between the universal conductance fluctuation and the weak localization effect in monolayer graphene is investigated. By comparing experimental results with the predictions of the weak localization theory for graphene, we find that the ratio of the elastic intervalley scattering time to the inelastic dephasing time varies in accordance with the conductance fluctuation; this is a clear evidence connecting the universal conductance fluctuation with the weak localization effect. We also find a series of scattering lengths that are related to the phase shifts caused by magnetic flux by Fourier analysis.

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“…Since the discovery of graphene [3][4][5][6], the anomalous transport behavior of its charge carriers has attracted a great deal of attention [7][8][9]. The phase coherent length of graphene at low temperatures can be as long as several hundred nanometers [30] or even micrometers [31]. It have been demonstrated experimentally that for graphene quantum dots smaller than 100 nm, the conductance peaks become strongly non-periodic, indicating a major contribution of the quantum confinement [32].…”

Section: Introductionmentioning

confidence: 99%

Conductance fluctuations in chaotic bilayer graphene quantum dots

et al. 2015

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Previous studies of quantum chaotic scattering established a connection between classical dynamics and quantum transport properties: Integrable or mixed classical dynamics can lead to sharp conductance fluctuations but chaos is capable of smoothing out the conductance variations. Relativistic quantum transport through single-layer graphene systems, for which the quasiparticles are massless Dirac fermions, exhibits, due to scarring, this classical-quantum correspondence, but sharp conductance fluctuations persist to a certain extent even when the classical system is fully chaotic. There is an open issue regarding the effect of finite mass on relativistic quantum transport. To address this issue, we study quantum transport in chaotic bilayer graphene quantum dots for which the quasiparticles have a finite mass. An interesting phenomenon is that, when traveling along the classical ballistic orbit, the quasiparticle tends to hop back and forth between the two layers, exhibiting a Zitterbewegung-like effect. We find signatures of abrupt conductance variations, indicating that the mass has little effect on relativistic quantum transport. In solid-state electronic devices based on Dirac materials, sharp conductance fluctuations are thus expected, regardless of whether the quasiparticle is massless or massive and whether there is chaos in the classical limit.

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Phase coherent transport in graphene nanoribbons and graphene nanoribbon arrays

Cited by 32 publications

References 29 publications

Localized charge carriers in graphene nanodevices

Localized charge carriers in graphene nanodevices

Relationship between conductance fluctuation and weak localization in graphene

Conductance fluctuations in chaotic bilayer graphene quantum dots

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