Equilibration of quantum hall edge states and its conductance fluctuations in graphene p-n junctions

Kumar, C. N.; Kuiri, Manabendra; Das, Anindya

doi:10.1016/j.ssc.2017.11.008

Cited by 10 publications

(5 citation statements)

References 41 publications

(76 reference statements)

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“…This specific configuration involves a p–n junction operating within the quantum Hall (QH) regime, resulting in the creation of QH interface channels along the p–n junction. [ 30–33 ] Notably, the equilibration of

\nu = 1

QH edge states does not support MZ interferometry, [ 34–36 ] but higher ν QH states generate spatially separated QH channels at the junction, forming a finite area enclosed by pathways of these channels. While random valley mixing at the junction interface diminishes quantum interference effects, we deliberately exclude any disorder or impurity responsible for the coherent‐to‐Ohmic transition, [ 36,37 ] in our study.…”

Section: Modelmentioning

confidence: 99%

Detecting Strain Effects Due to Nanobubbles in Graphene Mach–Zehnder Interferometers

Myoung,

Song,

Park

2024

Physica Status Solidi (b)

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Herein, the effect of elastic strain on a Mach–Zehnder (MZ) interferometer created by graphene p–n junction in quantum Hall regime is investigated. It is demonstrated that a Gaussian‐shaped nanobubble causes detuning of the quantum Hall conductance oscillations across the p–n junction, due to the strain‐induced local pseudo‐magnetic fields (PMFs). By performing a machine‐learning‐based Fourier analysis, the nanobubble‐induced Fourier component from the conductance oscillations originating from the external magnetic fields is differentiated. It is shown that the detuning of the conductance oscillations is due to the altered pathway of quantum Hall interface channels caused by the strain‐induced PMFs. In the presence of the nanobubble, a new Fourier component for a magnetic flux appears, and the corresponding MZ interferometry indicates that the enclosed area is reduced by half due to the strain‐mediated pathway between two quantum Hall interface channels. In the findings, the potential of using graphene as a strain sensor is suggested for developments in graphene‐based device fabrications and measurements technologies.

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\nu = 1

Section: Modelmentioning

confidence: 99%

Detecting Strain Effects Due to Nanobubbles in Graphene Mach–Zehnder Interferometers

Myoung,

Song,

Park

2024

Physica Status Solidi (b)

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“…When one fabricates millimetre-scale pnJ devices, it is crucial to ensure that large adjacent regions can accommodate a unipolar value of the carrier density, are opposite in charge carrier sign, and are separated by a sufficiently narrow pnJ to enable Landauer-Büttiker edge state propagation and equilibration [5][6][7][8][9][43][44][45][46][47][48].…”

Section: Adjustment Of the Carrier Densitymentioning

confidence: 99%

Development of gateless quantum Hall checkerboard p–n junction devices

Patel¹,

Marzano²,

Liu³

et al. 2020

J. Phys. D: Appl. Phys.

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Measurements of fractional multiples of the ν = 2 plateau quantized Hall resistance ( R H ≈ 12 906 Ω) were enabled by the utilization of multiple current terminals on millimetre-scale graphene p–n junction (pnJ) devices fabricated with interfaces along both lateral directions. These quantum Hall resistance checkerboard devices have been demonstrated to match quantized resistance outputs numerically calculated with the LTspice circuit simulator. From the devices’ functionality, more complex embodiments of the quantum Hall resistance checkerboard were simulated to highlight the parameter space within which these devices could operate. Moreover, these measurements suggest that the scalability of pnJ fabrication on millimetre or centimetre scales is feasible with regards to graphene device manufacturing by using the far more efficient process of standard ultraviolet lithography.

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“…Two difficult steps in successfully fabricating millimeterscale pnJ devices include the following: (1) uniformly doping large-area regions on epitaxial graphene (EG) such that it may exhibit both p-type and n-type behavior and (2) ensuring adequate junction narrowness to enable Landauer-Büttiker edge channel propagation and equilibration [5][6][7][8][9][48][49][50][51][52][53]. For the first case, common nanodevice fabrication practices such as using a top-gate are unable to be used due to an increasing probability of current leakage through the gate with lateral size.…”

Section: Introductionmentioning

confidence: 99%

Analysing quantized resistance behaviour in graphene Corbino p-n junction devices

Liu

Scaletta

Patel

et al. 2020

J. Phys. D: Appl. Phys.

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Just a few of the promising applications of graphene Corbino pnJ devices include two-dimensional Dirac fermion microscopes, custom programmable quantized resistors, and mesoscopic valley filters. In some cases, device scalability is crucial, as seen in fields like resistance metrology, where graphene devices are required to accommodate currents of the order 100 μA to be compatible with existing infrastructure. However, fabrication of these devices still poses many difficulties. In this work, unusual quantized resistances are observed in epitaxial graphene Corbino p-n junction devices held at the ν = 2 plateau ( R H ≈ 12906 Ω ) and agree with numerical simulations performed with the LTspice circuit simulator. The formulae describing experimental and simulated data are empirically derived for generalized placement of up to three current terminals and accurately reflect observed partial edge channel cancellation. These results support the use of ultraviolet lithography as a way to scale up graphene-based devices with suitably narrow junctions that could be applied in a variety of subfields.

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Equilibration of quantum hall edge states and its conductance fluctuations in graphene p-n junctions

Cited by 10 publications

References 41 publications

Detecting Strain Effects Due to Nanobubbles in Graphene Mach–Zehnder Interferometers

Detecting Strain Effects Due to Nanobubbles in Graphene Mach–Zehnder Interferometers

Development of gateless quantum Hall checkerboard p–n junction devices

Analysing quantized resistance behaviour in graphene Corbino p-n junction devices

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