Parity effect of bipolar quantum Hall edge transport around graphene antidots

Matsuo, Sadashige; Nakaharai, Shu; Komatsu, Katsuyoshi; Tsukagoshi, Kazuhito; Moriyama, Takahiro; Ono, Teruo; Kobayashi, Kensuke

doi:10.1038/srep11723

Cited by 8 publications

(13 citation statements)

References 30 publications

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“…When W p /L φ is increased, the edge-dependent features diminish and eventually in the incoherent limit (W p /L φ 1), we recover G = G 0 /2 for all kinds of edges. This corresponds to the conductance plateau measured experimentally 13,16,22,23 when (ν n , ν p ) = (2, −2). This value also coincides with the original theoretical prediction of Abanin and Levitov 28 , rederived in Refs.…”

Section: Results Without Disordersupporting

confidence: 72%

“…27 When the filling factors in the n-and p-parts are tuned to ν n = 2 and ν p = −2 respectively, the edge states propagating along the nanoribbon edges are spin degenerate and valley polarized, while at the n-p interface, valley degeneracy is preserved and four spin-and valley-degenerate channels co-propagate. In this regime, experimental works 13,16,22,23 show that the conductance is quantized to e 2 /h, in agreement with theory 28 assuming complete mode mixing along the n-p interface.…”

Section: Introductionsupporting

confidence: 84%

“…In addition to conductance measurements, [13][14][15][16][17][18][19][20][21][22][23][24] shot noise measurements 25,26 have demonstrated that a graphene n-p junction can act as a coherent beam splitter of electron-like and hole-like particles. Recently, a Mach-Zehnder edge-channel interferometer has been implemented in such a device, showing robust conductance oscillations with very high visibility.…”

Section: Introductionmentioning

confidence: 99%

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Graphene n−p junctions in the quantum Hall regime: Numerical study of incoherent scattering effects

Parmentier

Roulleau

et al. 2018

Phys. Rev. B

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We investigate electronic transport through a graphene n-p junction in the quantum Hall effect regime at high perpendicular magnetic field, when the filling factors in the n-doped and p-doped regions are fixed to 2 and -2 respectively. We compute numerically the conductance G, the noise Q and the Fano factor F of the junction when inelastic effects are included along the interface in a phenomenological way, by means of fictitious voltage probes. Using a scaling approach, we extract the system coherence length L φ and describe the full crossover between the coherent limit (W L φ ) and the incoherent limit (W L φ ), W being the interface length. While G saturates at the value e 2 /h in the incoherent regime, Q and F are found to vanish exponentially for large length W . Corrections due to disorder are also investigated. Our results are finally compared to available experimental data.

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Section: Results Without Disordersupporting

confidence: 72%

Section: Introductionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

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Graphene n−p junctions in the quantum Hall regime: Numerical study of incoherent scattering effects

Parmentier

Roulleau

et al. 2018

Phys. Rev. B

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“…A back-gate electrode is used to tune the carrier density of the whole area, whereas a top-gate electrode can locally tune the density, so that a p – n junction is formed there 9 19 . The insulating layer for the top gate is a crosslinked polymethyl methacrylate (PMMA) 17 19 . The optical picture of the device is shown in the upper panel of Fig.…”

Section: Resultsmentioning

confidence: 99%

“…It was found in the bipolar regime that the QH edge transport at the junction shows a peculiar fractional quantized conductance in the units of conductance quantum e 2 / h , where h is Planck's constant 9 . This exotic observation was phenomenologically attributed to the peculiar electron partition caused by uniform mixing of the QH edge states that co-propagate along the p – n junction 9 10 , which has been supported by intensive experimental works 11 12 13 14 15 16 17 . However, shot-noise measurements could directly provide a deeper insight into the microscopic dynamics of the electron partition process on the p – n junction.…”

mentioning

confidence: 79%

Edge mixing dynamics in graphene p–n junctions in the quantum Hall regime

et al. 2015

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Massless Dirac electron systems such as graphene exhibit a distinct half-integer quantum Hall effect, and in the bipolar transport regime co-propagating edge states along the p–n junction are realized. Additionally, these edge states are uniformly mixed at the junction, which makes it a unique structure to partition electrons in these edge states. Although many experimental works have addressed this issue, the microscopic dynamics of electron partition in this peculiar structure remains unclear. Here we performed shot-noise measurements on the junction in the quantum Hall regime as well as at zero magnetic field. We found that, in sharp contrast with the zero-field case, the shot noise in the quantum Hall regime is finite in the bipolar regime, but is strongly suppressed in the unipolar regime. Our observation is consistent with the theoretical prediction and gives microscopic evidence that the edge states are uniquely mixed along the p–n junction.

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