D. R. da Costa

Valley filtering using electrostatic potentials in bilayer graphene

Propagation of an electron wave packet through a quantum point contact (QPC) defined by electrostatic gates in bilayer graphene is investigated. The gates provide a bias between the layers, in order to produce an energy gap. If the gates on both sides of the contact produce the same bias, steps in the electron transmission probability are observed, as in the usual QPC. However, if the bias is inverted on one of the sides of the QPC, only electrons belonging to one of the Dirac valleys are allowed to pass, which provides a very efficient valley filtering.

Substrate effects on the exciton fine structure of black phosphorus quantum dots

We study the size-dependent exciton fine structure in monolayer black phosphorus quantum dots (BPQDs) deposited on different substrates (isolated, Si and SiO

Multilayered black phosphorus: From a tight-binding to a continuum description

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Valley filtering in graphene due to substrate-induced mass potential

) using a combination of tight-binding method to calculate the single-particle states, and the configuration interaction formalism to determine the excitonic spectrum. We demonstrate that the substrate plays a dramatic role on the excitonic gaps and excitonic spectrum of the QDs. For reasonably high dielectric constants (

Boundary conditions for phosphorene nanoribbons in the continuum approach

\varepsilon_{sub} \sim \varepsilon_{Si} = 11.7 \varepsilon_0

Energy shift and conduction-to-valence band transition mediated by a time-dependent potential barrier in graphene

), the excitonic gap can be described by a single power law

Geometry and edge effects on the energy levels of graphene quantum rings: A comparison between tight-binding and simplified Dirac models

E_X(R) = E_X^{(bulk)} + C/R^{\gamma}

Analytical study of the energy levels in bilayer graphene quantum dots

. For low dielectric constants

Wave-packet scattering on graphene edges in the presence of a pseudomagnetic field

\varepsilon_{sub} \leq \varepsilon_{SiO_2} = 3.9 \varepsilon_0

Unusual quantum confined Stark effect and Aharonov-Bohm oscillations in semiconductor quantum rings with anisotropic effective masses

, the size dependence of the excitonic gaps requires the sum of two power laws