Valley isospin of interface states in a graphene 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>p</mml:mi><mml:mi>n</mml:mi></mml:mrow></mml:math>
 junction in the quantum Hall regime

Trifunovic, Luka; Brouwer, Piet W.

doi:10.1103/physrevb.99.205431

Cited by 17 publications

(14 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This prediction was verified by Williams et al [2] in experimental transport measurements of the MLG n-p junction. Theoretical studies [5][6][7][8] showed that valley-isospin conservation plays an important role in the evolution of edge states into interface states along the n-p junction of MLG nanoribbons, confirming valley isospin conservation in ribbons with armchair boundaries [5,7]. Recent experimental studies also show that graphene n-p junction at high magnetic fields hosts (valley-and spin-polarized) edge channels propagating along the junction where coupling between those channels results in a Mach-Zehnder (MZ) interferometer [9] showing Aharonov-Bohm (AB) effect [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Electronic Mach-Zehnder interference in a bipolar hybrid monolayer-bilayer graphene junction

Mirzakhani¹,

Myoung²,

Peeters³

et al. 2022

Preprint

View full text Add to dashboard Cite

Graphene matter in a strong magnetic field, realizing one-dimensional quantum Hall channels, provides a unique platform for studying electron interference. Here, using the Landauer-Büttiker formalism along with the tight-binding model, we investigate the quantum Hall (QH) effects in unipolar and bipolar monolayer-bilayer graphene (MLG-BLG) junctions. We find that a Hall bar made of an armchair MLG-BLG junction in the bipolar regime results in valley-polarized edgechannel interferences and can operate a fully tunable Mach-Zehnder (MZ) interferometer device. Investigation of the bar-width and magnetic-field dependence of the conductance oscillations shows that the MZ interference in such structures can be drastically affected by the type of (zigzag) edge termination of the second layer in the BLG region [composed of vertical dimer or non-dimer atoms]. Our findings reveal that both interfaces exhibit a double set of Aharonov-Bohm interferences, with the one between two oppositely valley-polarized edge channels dominating and causing a largeamplitude conductance oscillation ranging from 0 to 2e 2 /h. We explain and analyze our findings by analytically solving the Dirac-Weyl equation for a gated semi-infinite MLG-BLG junction.

show abstract

Section: Introductionmentioning

confidence: 99%

Electronic Mach-Zehnder interference in a bipolar hybrid monolayer-bilayer graphene junction

Mirzakhani¹,

Myoung²,

Peeters³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…In this case, the spin-up channels from the P and N regions collide at the top and bottom “edge” intersections of the PN interface with the graphene edge below the side gates, leading to formation of their beam splitters (which are called valley splitters 2 ). The atomic structure of the graphene edge causes sharp potential change at the edge intersection, hence, scattering between the spin-up channels having opposite valley-isospin 15 , 16 . The two spin-up channels co-propagating along the PN interface and their beam splitters at the top and bottom edge intersections constitute the large interferometer that exhibits transmission oscillations of period ΔB = 20 mT as a function of the magnetic field (note that this period is slightly different from the one reported in ref.…”

Section: Resultsmentioning

confidence: 99%

Scaling behavior of electron decoherence in a graphene Mach-Zehnder interferometer

Lee

Assouline

et al. 2022

Nat Commun

View full text Add to dashboard Cite

Over the past 20 years, many efforts have been made to understand and control decoherence in 2D electron systems. In particular, several types of electronic interferometers have been considered in GaAs heterostructures, in order to protect the interfering electrons from decoherence. Nevertheless, it is now understood that several intrinsic decoherence sources fundamentally limit more advanced quantum manipulations. Here, we show that graphene offers a unique possibility to reach a regime where the decoherence is frozen and to study unexplored regimes of electron interferometry. We probe the decoherence of electron channels in a graphene quantum Hall PN junction, forming a Mach-Zehnder interferometer 1 , 2 , and unveil a scaling behavior of decay of the interference visibility with the temperature scaled by the interferometer length. It exhibits a remarkable crossover from an exponential decay at higher temperature to an algebraic decay at lower temperature where almost no decoherence occurs, a regime previously unobserved in GaAs interferometers.

show abstract

“…As an effective means of field regulation and control of valley polarization, the function of the magnetic field has been widely explored. For instance, a quantizing magnetic field generating the valley-polarized quantum Hall state in the graphene p−n junction has been investigated in theoretical studies [15,16,17,18,19] and confirmed in experiment with a high magnetic field [20]. Of course, the valley-polarized Landau level can be created under an even stronger magneitc field [21].…”

Section: Introductionmentioning

confidence: 90%

Controllable valley filter in graphene topological line defect with magnetic field

Tian

Ren

Zhou

et al. 2020

Preprint

View full text Add to dashboard Cite

The extended line defect of graphene is an extraordinary candidate in valleytronics while the high valley polarization can only occur for electrons with high incidence angles which brings about tremendous challenges to experimental realization. In this paper, we propose a simple scheme to filter one conical valley state by applying a local magnetic field. It is found that due to the movement of the Dirac points, the transmission profiles of the two valleys are shifted along the injection-angle axis at the same pace, resulting in the peak transmission of one valley state being reduced drastically while remaining unaffected for the other valley state, which induces nearly perfect valley polarization. This scheme can be easily implemented in experiments and plays a key role in graphene valleytronics.

show abstract

Valley isospin of interface states in a graphene pn junction in the quantum Hall regime

Cited by 17 publications

References 53 publications

Electronic Mach-Zehnder interference in a bipolar hybrid monolayer-bilayer graphene junction

Electronic Mach-Zehnder interference in a bipolar hybrid monolayer-bilayer graphene junction

Scaling behavior of electron decoherence in a graphene Mach-Zehnder interferometer

Controllable valley filter in graphene topological line defect with magnetic field

Contact Info

Product

Resources

About