@article{Pedrelli2019,
title = { Excitation of SPPs in graphene by a waveguide mode },
author = {D. C. Pedrelli and B. S. C. Alexandre and N. M. R. Peres},
doi = {10.1209/0295-5075/126/27001},
year = {2019},
date = {2019-04-01},
journal = {EPL},
volume = {126},
number = {27001},
abstract = {We present a semi-analytical model that predicts the excitation of surface-plasmon polaritons (SPPs) on a graphene sheet located in front of a sub-wavelength slit drilled in a thick metal screen. We identify the signature of the SPP in the transmission, reflection, and absorption curves. Following the previous literature on noble-metal plasmonics, we characterize the efficiency of excitation of SPPs in graphene computing a spatial probability density. This quantity shows the presence of plasmonics resonances dispersing with the Fermi energy, E-F, as root E-F, an unambiguous signature of graphene plasmons. Copyright (C) EPLA, 2019},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Catarina2019,
title = {Optical orientation with linearly polarized light in transition metal dichalcogenides},
author = {G. Catarina and J. Have and J. Fernandez-Rossier and N.M.R. Peres},
editor = {AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
doi = {10.1103/PhysRevB.99.125405},
year = {2019},
date = {2019-03-05},
journal = {PHYSICAL REVIEW B},
volume = {99},
number = {125405},
abstract = {We study the optical properties of semiconducting transition metal dichalcogenide monolayers under the influence of strong out-of-plane magnetic fields, using the effective massive Dirac model. We pay attention to the role of spin-orbit-coupling effects, doping level, and electron-electron interactions, treated at the Hartree-Fock level. We find that optically induced valley and spin imbalance, commonly attained with circularly polarized light, can also be obtained with linearly polarized light in the doped regime. Additionally, we explore an exchange-driven mechanism to enhance the spin-orbit splitting of the conduction band, in n-doped systems, controlling both the carrier density and the intensity of the applied magnetic field.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Silva2019,
title = {Far-infrared Tamm polaritons in a microcavity with incorporated graphene sheet},
author = {Jorge M. S. S. Silva and Mikhail Vasilevskiy },
editor = {Optical Society of America},
url = {https://doi.org/10.1364/OME.9.000244},
doi = {https://doi.org/10.1364/OME.9.000244},
year = {2019},
date = {2019-03-03},
journal = {Optical Materials Express},
volume = {9},
number = {1},
pages = {244-255},
abstract = {Tamm polaritons (TPs) are formed at the interface between a semi-infinite periodic dielectric structure (Bragg mirror) and another reflector. They couple to elementary excitations in the materials that form the interface, such as metal plasmons or semiconductor excitons. Here we discuss the formation of TPs in the far-infrared spectral range, in the optical-phonon reststrahlen band of a polar semiconductor such as GaAs, attached to a Bragg reflector (BR). Their dispersion relation and the frequency window for the TP existence are calculated for a GaAs-BR interface. Microcavity structures containing a gap between the two reflectors are also considered, including those containing an inserted graphene layer and the possibility of tuning of the TP states by changing the graphene’s Fermi energy is demonstrated.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Ferreira2019,
title = {Excitons in hexagons boron nitride single-laye a new platform for polaritonics in the ultraviolet},
author = {F. Ferreira and A. J. Chaves and N.M.R. Peres and R.M. Ribeiro},
doi = {10.1364/JOSAB.36.000674},
year = {2019},
date = {2019-03-01},
journal = {JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL },
volume = {36},
number = {3},
pages = {674-683},
abstract = {The electronic and optical properties of 2D hexagonal boron nitride are studied using first principle calculations. GW and Bethe-Salpeter equation (BSE) methods are employed in order to predict with better accuracy the excited and excitonic properties of this material. We determine the values of the band gap (732 eV, indirect), optical gap (5.58 eV), and excitonic binding energies (2.19 eV) and analyze the excitonic wave functions. We also calculate the exciton energies following an equation of motion formalism and the Elliot formula and find good agreement with the GW + BSE method. The optical properties are studied for the TM and TE modes, showing that 2D hexagonal boron nitride (hBN) is a good candidate for polaritonics in the IN range. In particular, it is shown that a single layer of hBN can act as an almost perfect mirror for ultraviolet electromagnetic radiation. (C) 2019 Optical Society of America.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Alves2019,
title = {Two-dimensional materials in the presence of nonplanar interfaces},
author = {Danilo T. Alves and Nuno M. R. Peres},
editor = {AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
doi = {10.1103/PhysRevB.99.075437},
year = {2019},
date = {2019-02-28},
journal = {PHYSICAL REVIEW B},
volume = {99},
number = {075437},
abstract = {We consider a planar two-dimensional system between two media with different dielectric constants and in the presence of a third dielectric medium separated by a nonplanar interface. Extending a perturbative method for solving Poisson's equation, developed by Clinton, Esrick, and Sacks [Phys. Rev. B 31, 7540 (1985)], in the presence of nonplanar conducting boundaries to the situation proposed here, we obtain, up to the first order in terms of the function which defines the nonplanar interface, the effective potential, the effective electrostatic field, and the effective dielectric constant for the planar 2D system. We also point to the existence of an effective external field acting in-plane in the 2D system. Implications of the results to properties of 2D systems are discussed. In the limit of planar surfaces, vacuum-dielectric or vacuum-conducting media, our results are in agreement with those found in the literature.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Peres2019,
title = {Monolayer transition metal dichalcogenides in strong magnetic fields: Validating the Wannier model using a microscopic calculation},
author = {J. Have, G. Catarina, T. G. Pedersen, and Nuno M. R. Peres},
editor = {American Physical Society},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.035416},
doi = {10.1103/PhysRevB.99.035416},
year = {2019},
date = {2019-01-09},
journal = {Physical Review B, },
volume = {99},
number = {1},
pages = {035416},
abstract = {Using an equation of motion (EOM) approach, we calculate excitonic properties of monolayer transition metal dichalcogenides perturbed by an external magnetic field. We compare our findings to the widely used Wannier model for excitons in two-dimensional materials and to recent experimental results. We find good agreement between the calculated excitonic transition energies and the experimental results. In addition, we find that the exciton energies calculated using the EOM approach are slightly lower than the ones calculated using the Wannier model. Finally, we also show that the effect of the dielectric environment on the magnetoexciton transition energy is minimal due to counteracting changes in the exciton energy and the exchange self-energy correction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Pereira2018,
title = {Surface Plasmon Resonance in a Metallic Nanoparticle Embedded in a Semiconductor },
author = {Rui M. S. Pereira , Joel Borges , Georgui V. Smirnov Filipe Vaz , and M. I. Vasilevskiy},
editor = {American Chemical Society},
url = {https://pubs.acs.org/doi/10.1021/acsphotonics.8b01430},
doi = {https://pubs.acs.org/doi/10.1021/acsphotonics.8b01430},
year = {2018},
date = {2018-12-18},
journal = {ACS photonics},
volume = {6},
number = {1},
pages = {204-210},
abstract = {We consider the effect of electromagnetic coupling between localized surface plasmons in a metallic nanoparticle (NP) and excitons or weakly interacting electron–hole pairs in a semiconductor matrix where the NP is embedded. An expression is derived for the NP polarizability renormalized by this coupling and two possible situations are analyzed, both compatible with the conditions for Fano-type resonances: (i) a narrow bound exciton transition overlapping with the NP surface plasmon resonance (SPR), and (ii) SPR overlapping with a parabolic absorption band due to electron–hole transitions in the semiconductor. The absorption band line shape is strongly non-Lorentzian in both cases and similar to the typical Fano spectrum in the case (i). However, it looks differently in the situation (ii) that takes place for gold NPs embedded in a CuO film and the use of the renormalized polarizability derived in this work permits to obtain a very good fit to the experimentally measured LSPR line shape.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}