Graphene-based van der Waals heterostructures take advantage of tailoring spin-orbit coupling (SOC) in the graphene layer by proximity effect. At long wavelength---saddled electronic states near Dirac points---the proximitized features can be effectively modeled Hamiltonian involving novel SOC terms and allow for an admixture tangential radial spin-textures---by so-called Rashba angle ${\ensuremath{\theta}}_{\mathrm{R}}$. Taking such effective models we perform realistic large-scale...

We demonstrate that the phenomenon of current confinement along graphene $n\ensuremath{-}p$ junctions at high magnetic fields can be used to form an Aharonov-Bohm interferometer. The interference system exploits a closed junction induced by floating gate within sample, and coupling currents with edge in quantum Hall regime. Operation device requires splitting contacts which is found for armchair ribbons low Fermi energy.

Large-angle twisted bilayer graphene (tBLG) is known to be electronically decoupled due the spatial separation of Dirac cones corresponding individual layers in reciprocal space. The close spacing between causes strong capacitive coupling, opening possibilities for applications atomically thin devices. Here, we present a self-consistent quantum capacitance model electrostatics layers, and further generalize it deal with tBLG at finite magnetic field large-angle double zero field. We probe...

We describe dynamics of spin and valley transitions driven by alternating electric fields in quantum dots defined electrostatically within semiconducting carbon nanotubes (CNT). use the tight-binding approach to states localized a dot taking into account circumferential spin-orbit interaction due $s\text{\ensuremath{-}}p$ hybridization external fields. The basis eigenstates is used solution time-dependent Schr\"odinger equation for description flips intervalley that are periodic perturbation...

We consider conductance mapping of the snake orbits confined along $n\ensuremath{-}p$ junction defined in graphene by electrostatic doping quantum Hall regime. explain periodicity oscillations at magnetic field and Fermi energy scales properties as a conducting channel. evaluate maps for floating gate scanning surface device. In conditions currents flow near edges sample junction. The resolves only not edges. are found with related to cyclotron scattering current. Stronger probe potentials...

We investigate magnetic deflection of currents that flow across the Aharonov-Bohm interferometers defined in graphene. consider devices induced by closed $n\text{\ensuremath{-}}p$ junctions nanoribbons as well etched quantum rings. The effects on conductance are strictly correlated with properties ring-localized quasibound states. energy these states, their lifetime, and periodicity oscillations determined orientation current circulating within interferometer. formation high harmonics at...

Quantum Hall effects offer a formidable playground for the investigation of quantum transport phenomena. Edge modes can be deflected, branched, and mixed by designing suitable potential landscape in two-dimensional conducting system subject to strong magnetic field. In present work, we demonstrate buried split-gate architecture use it control electron conduction large-scale single-crystal monolayer graphene grown chemical vapor deposition. The edge trajectories is demonstrated observation...

Abstract We study electrostatic quantum dot confinement for charge carriers in silicene. The is formed by vertical electric field surrounding the area. resulting energy gap outside of traps within, and difference potentials on buckled silicene sublattices produces nonzero carrier masses dot. defined inside a flake with both atomistic tight-binding approach as well continuum approximation circularly symmetric potential. find localization states within their decoupling from edge that makes...

We analyze the effective Land\'e factor ${g}^{*}$ and its dependence on orientation of external magnetic field for a quantum point contact defined in two-dimensional electron gas. The paper simulates experimental procedure evaluation factors from transconductance biased device an field. contributions orbital effects field, electron-electron interaction, spin-orbit (SO) coupling are studied low-temperature conditions (0.5 K). anisotropy in-plane orientation, which seems counterintuitive...

We show evidence of the backscattering quantum Hall edge channels in a narrow graphene bar, induced by gating effect conducting tip scanning gate microscope, which we can position with nanometer precision. full control over and are able, because spatial variation potential, to separate copropagating creating junctions between regions different charge carrier density, that have not been observed devices based on top or split gates. The solution corresponding scattering problem is presented...

We provide a theoretical study of the conductance response systems based on graphene nanoribbon to potential scanning probe. The is Landauer approach for tight-binding Hamiltonian with an implementation quantum transmitting boundary method and covers homogenous nanoribbons, their asymmetric narrowing point contacts various profiles. maps at low Fermi energies resolve formation n-p junctions induced by probe presence zigzag-armchair segments edges inhomogeneous ribbons. For nanoribbons...

Recent experimental progress on Bernal-stacked bilayer graphene (BLG) has shown its versatility not only in exotic physics but also practical applications electronic devices thanks to gate-tunable band gap. Modeling and simulating quantum transport experiments BLG samples, however, so far remained rather limited. Here we present a four-band effective square-lattice model demonstrate power reliability by revisiting experiments, including the classic magnetotransport of Hall effect transverse...

Graphene with its dispersion relation resembling that of photons offers ample opportunities for applications in electron optics. The spacial variation carrier density by external gates can be used to create waveguides, analogy optical fiber, additional confinement the carriers bipolar junctions leading formation few transverse guiding modes. We show waveguides created gating graphene carbon nanotubes (CNTs) allow obtaining sharp conductance plateaus, and propose Aharonov-Bohm two-path...

We study graphene quantum point contacts (QPC) and imaging of the backscattering Fermi level wave function by potential introduced a scanning probe. consider both etched single-layer QPCs as well ones formed bilayer patches deposited at sides monolayer conducting channel using an atomistic tight binding approach. A computational method is developed to effectively simulate infinite plane outside QPC box finite size. demonstrate that in spite Klein phenomenon interference due circular n-p...

We consider a small $p$-type island defined within an $n$-type graphene nanoribbon induced by the potential of floating electrode. In quantum Hall conditions supports persistent currents localized at $n\ensuremath{-}p$ junction. When coupled to edge, acts as Aharonov-Bohm interferometer. evaluate electrostatic gate ribbon near charge neutrality point and equilibration both sides The incoherent is introduced virtual-probes technique. describe evolution coherent conductance oscillations...

A simple and reliable finite-difference approach is presented for solution of the Dirac equation eigenproblem states confined in rotationally symmetric systems. The method sets boundary condition spinor wave function components at external edge system then sweeps radial mesh search energies which conditions are met inside flake. sweep that performed from towards origin allows application a two-point quotient first derivative, prevents fermion doubling problem appearing with spurious...

With the advent of high mobility encapsulated graphene devices, new electronic components ruled by Dirac fermions optics have been envisioned and realized. The main building blocks electron-optics devices are gate-defined p-n junctions, which guide, transmit refract charge carriers, just like prisms lenses in optics. reflection transmission governed junction smoothness, a parameter difficult to tune conventional devices. Here we create junctions graphene, using polarized tip scanning gate...

We study spin control for an electron confined in a flake of silicene. find that the lowest-energy conduction-band levels are split by diagonal intrinsic spin-orbit coupling into Kramers doublets with definite projection on orbital magnetic moment. AC electric fields using non-diagonal Rashba component interactions time-dependent atomistic tight-binding approach. The produce Rabi spin-flips times order nanosecond. These can be reduced to tens picoseconds provided vertical field is tuned...

We consider graphene on monolayer ${\mathrm{WSe}}_{2}$ and the spin-orbit coupling induced by transition-metal dichalcogenide substrate for application to spin-active devices. study quantum dots rings as tunable spin filters inverters. use an atomistic tight-binding model well Dirac equation determine stationary states confined in rings. Next, we solve spin-transport problem connected nanoribbon leads. The systems zigzag nanoribbons at low magnetic fields act provide strongly polarized current.

We study chiral wave packets moving along the zero line of a symmetry-breaking potential vertical electric field in buckled silicene using an atomistic tight-binding approach with initial conditions set by analytical solution Dirac equation. demonstrate that packet moves constant untrembling velocity and preserved shape line. Backscattering edge crystal is observed appears transition from $K$ to ${K}^{\ensuremath{'}}$ valley or vice versa. propose profile splits next produces interference...

We consider observation of Aharonov-Bohm oscillations in clean systems based on the flow topologically protected currents silicene and bilayer graphene. The chiral channels these materials are defined by flips vertical electric field. line flip confines flowing along it direction determined valley. present an field profile that forms a crossed ring to which four terminals can be attached, find conductance matrix elements oscillate perpendicular magnetic spite absence backscattering. propose...

We consider a dilute fluorinated graphene nanoribbon as spin-active element. The fluorine adatoms introduce local spin-orbit Rashba interaction that induces spin precession for electron passing by. involving single adatom is infinitesimal and accumulation of the spin-precession events with many passages under necessary to accomplish flip. In order arrange this accumulation, circular $n\text{\ensuremath{-}}p$ junction can be introduced ribbon by, e.g., potential tip an atomic force...

We present an efficient numerical approach for treating ballistic quantum transport across devices described by tight-binding (TB) Hamiltonians designated to systems with localized potential defects. The method is based on the wave function matching approach, Lippmann-Schwinger equation (LEQ), and scattering matrix formalism. show that number of elements Green's be evaluated unperturbed system can essentially reduced projection time reversed functions LEQ which radically improves speed...