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“Band structure, density of states, and transmission in graphene bilayer superlattices”. Barbier M, Vasilopoulos P, Peeters FM, Pereira JM, AIP conference proceedings 1199, 547 (2009). http://doi.org/10.1063/1.3295550
Abstract: The energy spectrum and density of states of graphene bilayer superlattices (SLs) are evaluated. We take into account doping and/or gating of the layers as well as tunnel coupling between them. In addition, we evaluate the transmission through such SLs and through single or double barriers. The transmission exhibits a strong dependence on the direction of the incident wave vector.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1063/1.3295550
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“Bilayer graphene with single and multiple electrostatic barriers: band structure and transmission”. Barbier M, Vasilopoulos P, Peeters FM, Pereira JM, Physical review : B : solid state 79, 155402 (2009). http://doi.org/10.1103/PhysRevB.79.155402
Abstract: We evaluate the electronic transmission and conductance in bilayer graphene through a finite number of potential barriers. Further, we evaluate the dispersion relation in a bilayer graphene superlattice with a periodic potential applied to both layers. As a model we use the tight-binding Hamiltonian in the continuum approximation. For zero bias the dispersion relation shows a finite gap for carriers with zero momentum in the direction parallel to the barriers. This is in contrast to single-layer graphene where no such gap was found. A gap also appears for a finite bias. Numerical results for the energy spectrum, conductance, and the density of states are presented and contrasted with those pertaining to single-layer graphene.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 74
DOI: 10.1103/PhysRevB.79.155402
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“Chiral states in bilayer graphene : magnetic field dependence and gap opening”. Zarenia M, Pereira JM, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 84, 125451 (2011). http://doi.org/10.1103/PhysRevB.84.125451
Abstract: At the interface of electrostatic potential kink profiles, one-dimensional chiral states are found in bilayer graphene (BLG). Such structures can be created by applying an asymmetric potential to the upper and the lower layers of BLG. We found the following: (i) due to the strong confinement by the single kink profile, the unidirectional states are only weakly affected by a magnetic field; (ii) increasing the smoothness of the kink potential results in additional bound states, which are topologically different from those chiral states; and (iii) in the presence of a kink-antikink potential, the overlap between the oppositely moving chiral states results in the appearance of crossing and anticrossing points in the energy spectrum. This leads to the opening of tunable minigaps in the spectrum of the unidirectional topological states.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 50
DOI: 10.1103/PhysRevB.84.125451
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“Cyclotron resonance of trilayer graphene”. Sena SHR, Pereira JM, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 86, 085412 (2012). http://doi.org/10.1103/PhysRevB.86.085412
Abstract: The cyclotron resonance energies, the corresponding oscillator strengths, and the cyclotron absorption spectrum for trilayer graphene are calculated for both ABA and ABC stacking. A gate potential across the stacked layers leads to (1) a reduction of the transition energies, (2) a lifting of the degeneracy of the zero Landau level, and (3) the removal of the electron-hole symmetry.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PhysRevB.86.085412
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“The electronic properties of graphene and graphene ribbons under simple shear strain”. Sena SHR, Pereira JM, Farias GA, Peeters FM, Costa Filho RN, Journal of physics : condensed matter 24, 375301 (2012). http://doi.org/10.1088/0953-8984/24/37/375301
Abstract: A tight-binding model is used to study the energy band of graphene and graphene ribbon under simple shear strain. The ribbon consists of lines of carbon atoms in an armchair or zigzag orientation where a simple shear strain is applied in the x-direction keeping the atomic distances in the y-direction unchanged. Such modification in the lattice gives an energy band that differs in several aspects from the one without any shear and with pure shear. The changes in the spectrum depend on the line displacement of the ribbon, and also on the modified hopping parameter. It is also shown that this simple shear strain tunes the electronic properties of both graphene and graphene ribbon, opening and closing energy gaps for different displacements of the system. The modified density of states is also shown.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 15
DOI: 10.1088/0953-8984/24/37/375301
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“Electrostatically confined quantum rings in bilayer graphene”. Zarenia M, Pereira JM, Peeters FM, Farias GA, Nano letters 9, 4088 (2009). http://doi.org/10.1021/nl902302m
Abstract: We propose a new system where electron and hole states are electrostatically confined into a quantum ring in bilayer graphene. These structures can be created by tuning the gap of the graphene bilayer using nanostructured gates or by position-dependent doping. The energy levels have a magnetic field (B0) dependence that is strikingly distinct from that of usual semiconductor quantum rings. In particular, the eigenvalues are not invariant under a B0 ¨ −B0 transformation and, for a fixed total angular momentum index m, their field dependence is not parabolic, but displays two minima separated by a saddle point. The spectra also display several anticrossings, which arise due to the overlap of gate-confined and magnetically confined states.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 12.712
Times cited: 42
DOI: 10.1021/nl902302m
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“Geometry and edge effects on the energy levels of graphene quantum rings : a comparison between tight-binding and simplified Dirac models”. da Costa DR, Chaves A, Zarenia M, Pereira JM, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 89, 075418 (2014). http://doi.org/10.1103/PhysRevB.89.075418
Abstract: We present a systematic study of the energy spectra of graphene quantum rings having different geometries and edge types in the presence of a perpendicular magnetic field. Results are obtained within the tight-binding (TB) and Dirac models and we discuss which features of the former can be recovered by using the approximations imposed by the latter. Energy levels of graphene quantum rings obtained by diagonalizing the TB Hamiltonian are demonstrated to be strongly dependent on the rings geometry and the microscopical structure of the edges. This makes it difficult to recover those spectra by the existing theories that are based on the continuum (Dirac) model. Nevertheless, our results show that both approaches (i.e., TB and Dirac model) may provide similar results, but only for very specific combinations of ring geometry and edge types. The results obtained by a simplified model describing an infinitely thin circular Dirac ring show good agreement with those obtained for hexagonal and rhombus armchair graphene rings within the TB model. Moreover, we show that the energy levels of a circular quantum ring with an infinite mass boundary condition obtained within the Dirac model agree with those for a ring defined by a ring-shaped staggered potential obtained within the TB model.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 56
DOI: 10.1103/PhysRevB.89.075418
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“Graphene-based quantum wires”. Pereira JM Jr, Mlinar V, Peeters FM, Vasilopoulos P, AIP conference proceedings
T2 –, 28th International Conference on the Physics of Semiconductors (ICPS-28), JUL 24-28, 2006, Vienna, AUSTRIA , 721 (2007)
Abstract: We investigate the properties of carriers in graphene-based quantum wires created by potential barriers, by means of analytical and numerical calculations. We obtain expressions for the energy spectrum as a function of barrier height, well width and linear momentum along the wire. The results demonstrate a direction-dependent resonant transmission across the potential well.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
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“Klein tunneling in single and multiple barriers in graphene”. Pereira JM, Peeters FM, Chaves A, Farias GA, Semiconductor science and technology 25, 033002 (2010). http://doi.org/10.1088/0268-1242/25/3/033002
Abstract: We review the transmission properties of carriers interacting with potential barriers in graphene. The tunneling of electrons and holes in quantum structures in graphene is found to display features that are in marked contrast with those of other systems. In particular, the interaction between the carriers with electrostatic potential barriers can be related to the propagation of electromagnetic waves in media with negative refraction indices, also known as metamaterials. This behavior becomes evident as one calculates the time evolution of wavepackets propagating across the barrier interface. In addition, we discuss the effect of trigonal warping on the tunneling through potential barriers.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.305
Times cited: 83
DOI: 10.1088/0268-1242/25/3/033002
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“Landau levels in asymmetric graphene trilayer”. Sena SHR, Pereira JM, Peeters FM, Farias GA, Physical review : B : condensed matter and materials physics 84, 205448 (2011). http://doi.org/10.1103/PhysRevB.84.205448
Abstract: The electronic spectrum of three coupled graphene layers (graphene trilayers) is investigated in the presence of an external magnetic field. We obtain analytical expressions for the Landau level spectrum for both the ABA and ABC type of stacking, which exhibit very different dependence on the magnetic field. We show that layer asymmetry and an external gate voltage can strongly influence the properties of the system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 30
DOI: 10.1103/PhysRevB.84.205448
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“Landau levels in graphene bilayer quantum dots”. Pereira JM, Peeters FM, Vasilopoulos P, Costa Filho RN, Farias GA, Physical review : B : solid state 79, 195403 (2009). http://doi.org/10.1103/PhysRevB.79.195403
Abstract: We investigate localized electron and hole states in parabolic quantum dots of biased graphene bilayers in the presence of a perpendicular magnetic field. These quantum dots can be created by means of nanostructured gates or by position-dependent doping, which can create a gap in the otherwise gapless dispersion of a graphene bilayer. Numerical results show the energy levels of confined electrons and holes as a function of the dot parameters and the magnetic field. Remarkable crossings of energy levels are found.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 29
DOI: 10.1103/PhysRevB.79.195403
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“Simplified model for the energy levels of quantum rings in single layer and bilayer graphene”. Zarenia M, Pereira JM, Chaves A, Peeters FM, Farias GA, Physical review : B : condensed matter and materials physics 81, 045431 (2010). http://doi.org/10.1103/PhysRevB.81.045431
Abstract: Within a minimal model, we present analytical expressions for the eigenstates and eigenvalues of carriers confined in quantum rings in monolayer and bilayer graphene. The calculations were performed in the context of the continuum model by solving the Dirac equation for a zero width ring geometry, i.e., by freezing out the carrier radial motion. We include the effect of an external magnetic field and show the appearance of Aharonov-Bohm oscillations and of a nonzero gap in the spectrum. Our minimal model gives insight on the energy spectrum of graphene-based quantum rings and models different aspects of finite width rings.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 76
DOI: 10.1103/PhysRevB.81.045431
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“Snake states in graphene quantum dots in the presence of a p-n junction”. Zarenia M, Pereira JM Jr, Peeters FM, Farias GA, Physical review : B : condensed matter and materials physics 87, 035426 (2013). http://doi.org/10.1103/PhysRevB.87.035426
Abstract: We investigate the magnetic interface states of graphene quantum dots that contain p-n junctions. Within a tight-binding approach, we consider rectangular quantum dots in the presence of a perpendicular magnetic field containing p-n as well as p-n-p and n-p-n junctions. The results show the interplay between the edge states associated with the zigzag terminations of the sample and the snake states that arise at the p-n junction due to the overlap between electron and hole states at the potential interface. Remarkable localized states are found at the crossing of the p-n junction with the zigzag edge having a dumb-bell-shaped electron distribution. The results are presented as a function of the junction parameters and the applied magnetic flux. DOI: 10.1103/PhysRevB.87.035426
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 16
DOI: 10.1103/PhysRevB.87.035426
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“Topological confinement in an antisymmetric potential in bilayer graphene in the presence of a magnetic field”. Zarenia M, Pereira JM, Peeters FM, Farias G de A, Nanoscale research letters 6, 452 (2011). http://doi.org/10.1186/1556-276X-6-452
Abstract: We investigate the effect of an external magnetic field on the carrier states that are localized at a potential kink and a kink-antikink in bilayer graphene. These chiral states are localized at the interface between two potential regions with opposite signs.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.833
Times cited: 4
DOI: 10.1186/1556-276X-6-452
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“Topological confinement in graphene bilayer quantum rings”. Xavier LJP, Pereira JM, Chaves A, Farias GA, Peeters FM, Applied physics letters 96, 212108 (2010). http://doi.org/10.1063/1.3431618
Abstract: We find localized electron and hole states in a ring-shaped potential kink in biased bilayer graphene. Within the continuum description, we show that for sharp potential steps the Dirac equation describing carrier states close to the K (or K′) point of the first Brillouin zone can be solved analytically for a circular kink/antikink dot. The solutions exhibit interfacial states which exhibit AharonovBohm oscillations as functions of the height of the potential step and/or the radius of the ring.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 29
DOI: 10.1063/1.3431618
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“Topological confinement in trilayer graphene”. de Sena SHR, Pereira JM, Peeters FM, Farias GA, Physical review : B : condensed matter and materials physics 89, 035420 (2014). http://doi.org/10.1103/PhysRevB.89.035420
Abstract: We calculate the spectrum of states that are localized at the interface between two regions of opposite bias in trilayer graphene (TLG). These potential profiles, also known as potential kinks, have been predicted to support two different branches of localized states for the case of bilayer graphene, and show similarities to the surface states of topological insulators. On the other hand, we found that ABC stacked TLG exhibits three different unidimensional branches of states in each valley that are confined to the kink interface. They have the property E(k(y)) = -E(-k(y)) when belonging to the same valley and E-K(k(y)) = -E-K' (-k(y)). A kink-antikink potential profile opens a gap in the spectrum of these one-dimensional states.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PhysRevB.89.035420
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“Valley polarization due to trigonal warping on tunneling electrons in graphene”. Pereira JM, Peeters FM, Costa Filho RN, Farias GA, Journal of physics : condensed matter 21, 045301 (2009). http://doi.org/10.1088/0953-8984/21/4/045301
Abstract: The effect of trigonal warping on the transmission of electrons tunneling through potential barriers in graphene is investigated. We present calculations of the transmission coefficient for single and double barriers as a function of energy, incidence angle and barrier heights. The results show remarkable valley-dependent directional effects for barriers oriented parallel to the armchair or parallel to the zigzag direction. These results indicate that electrostatic gates can be used as valley filters in graphene-based devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 78
DOI: 10.1088/0953-8984/21/4/045301
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“Hexagonal-shaped monolayer-bilayer quantum disks in graphene : a tight-binding approach”. da Costa, Zarenia M, Chaves A, Pereira JM Jr, Farias GA, Peeters FM, Physical review B 94, 035415 (2016). http://doi.org/10.1103/PhysRevB.94.035415
Abstract: Using the tight-binding approach, we investigate confined states in two different hybrid monolayer-bilayer systems: (i) a hexagonal monolayer area surrounded by bilayer graphene in the presence of a perpendicularly applied electric field and (ii) a hexagonal bilayer graphene dot surrounded by monolayer graphene. The dependence of the energy levels on dot size and external magnetic field is calculated. We find that the energy spectrum for quantum dots with zigzag edges consists of states inside the gap which range from dot-localized states, edge states, to mixed states coexisting together, whereas for dots with armchair edges, only dot-localized states are observed.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 11
DOI: 10.1103/PhysRevB.94.035415
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“Magnetic properties of bilayer graphene quantum dots in the presence of uniaxial strain”. Nascimento JS, da Costa DR, Zarenia M, Chaves A, Pereira JM Jr, Physical review B 96, 115428 (2017). http://doi.org/10.1103/PHYSREVB.96.115428
Abstract: Using the tight-binding approach coupled with mean-field Hubbard model, we theoretically study the effect of mechanical deformations on the magnetic properties of bilayer graphene (BLG) quantum dots (QDs). Results are obtained for AA-and AB(Bernal)-stacked BLG QDs, considering different geometries (hexagonal, triangular and square shapes) and edge types (armchair and zigzag edges). In the absence of strain, our results show that (i) the magnetization is affected by taking different dot sizes only for hexagonal BLG QDs with zigzag edges, exhibiting different critical Hubbard interactions, and (ii) the magnetization does not depend on the interlayer hopping energies, except for the geometries with zigzag edges and AA stacking. In the presence of in-plane and uniaxial strain, for all geometries we obtain two different magnetization regimes depending on the applied strain amplitude. The appearance of such different regimes is due to the breaking of layer and sublattice symmetries in BLG QDs.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PHYSREVB.96.115428
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“Tunneling properties in α-T₃, lattices : effects of symmetry-breaking terms”. Cunha SM, da Costa DR, Pereira JM Jr, Costa Filho RN, Van Duppen B, Peeters FM, Physical review B 105, 165402 (2022). http://doi.org/10.1103/PHYSREVB.105.165402
Abstract: The alpha-T3 lattice model interpolates a honeycomb (graphene-like) lattice and a T3 (also known as dice) lattice via the parameter alpha. These lattices are made up of three atoms per unit cell. This gives rise to an additional dispersionless flat band touching the conduction and valence bands. Electrons in this model are analogous to Dirac fermions with an enlarged pseudospin, which provides unusual tunneling features like omnidirectional Klein tunneling, also called super-Klein tunneling (SKT). However, it is unknown how small deviations in the equivalence between the atomic sites, i.e., variations in the alpha parameter, and the number of tunnel barriers changes the transmission properties. Moreover, it is interesting to learn how tunneling occurs through regions where the energy spectrum changes from linear with a middle flat band to a hyperbolic dispersion. In this paper we investigate these properties, its dependence on the number of square barriers and the alpha parameter for either gapped and gapless cases. Furthermore, we compare these results to the case where electrons tunnel from a region with linear dispersion to a region with a bandgap. In the latter case, contrary to tunneling through a potential barrier, the SKT is no longer observed. Finally, we find specific cases where transmission is allowed due to a symmetry breaking of sublattice equivalence.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
DOI: 10.1103/PHYSREVB.105.165402
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