The one-way quantum computer

Physical Review B

Graphene has been hailed as a wonderful material in electronics, and recently, it is the rising star in photonics, as well. The wonderful optical properties of graphene afford multiple functions of signal emitting, transmitting, modulating, and detection to be realized in one material. In this paper, the latest progress in graphene photonics, plasmonics, and broadband optoelectronic devices is reviewed. Particular emphasis is placed on the ability to integrate graphene photonics onto the silicon platform to afford broadband operation in light routing and amplification, which involves components like polarizer, modulator, and photodetector. Other functions like saturable absorber and optical limiter are also reviewed.

Graphene photonics, plasmonics, and broadband optoelectronic devices.

Tables of integrals

The stability of two-dimensional (2D) layers and membranes is subject of a long standing theoretical debate. According to the so called Mermin-Wagner theorem, long wavelength fluctuations destroy the long-range order for 2D crystals. Similarly, 2D membranes embedded in a 3D space have a tendency to be crumpled. These dangerous fluctuations can, however, be suppressed by anharmonic coupling between bending and stretching modes making that a two-dimensional membrane can exist but should present strong height fluctuations. The discovery of graphene, the first truly 2D crystal and the recent experimental observation of ripples in freely hanging graphene makes these issues especially important. Beside the academic interest, understanding the mechanisms of stability of graphene is crucial for understanding electronic transport in this material that is attracting so much interest for its unusual Dirac spectrum and electronic properties. Here we address the nature of these height fluctuations by means of straightforward atomistic Monte Carlo simulations based on a very accurate many-body interatomic potential for carbon. We find that ripples spontaneously appear due to thermal fluctuations with a size distribution peaked around 70 \AA which is compatible with experimental findings (50-100 \AA) but not with the current understanding of stability of flexible membranes. This unexpected result seems to be due to the multiplicity of chemical bonding in carbon.

Intrinsic ripples in graphene

This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac-Schrodinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

Electronic and optical properties of strained graphene and other strained 2D materials: a review.

Electronic and optical properties of strained graphene and other strained 2D materials: a review

The effects of floppy modes in the thermodynamical properties of a system are studied From thermodynamical arguments, we deduce that floppy modes are not at zero frequency and thus a modified Debye model is used to take into account this effect The model predicts a deviation from the Debye law at low temperatures Then, the connection between the topography of the energy landscape, the topology of the phase space, and the rigidity of a glass is explored As a result, we relate the number of constraints and floppy modes to the statistics of the landscape We apply these ideas to a simple model for which we provide an approximate expression for the number of energy basins as a function of the rigidity This helps to understand certain features of the glass transition, like the jump in the specific heat or the reversible window observed in chalcogenide glasses

http://www.fisica.unam.mx/personales/naumis/index_archivos/physrevE05.pdf

Energy landscape and rigidity.

The stochastic matrix method is used to describe the statistical processes that take place when a glass is formed. We stress the physical features of the model and the relevancy of the hypotheses made. The theory is applied to various types of binary and ternary chalcogenide glasses, and the predictions of the model are compared with the experimental data. We also reveal the influence of doping on the transition temperature. The theory is extended to the case of growing a disordered solid on a substrate.

Gerardo G. Naumis

Papers

Electronic and optical properties of strained graphene and other strained 2D materials: a review.

Electronic and optical properties of strained graphene and other strained 2D materials: a review

Energy landscape and rigidity.

Models of Disorder

Generalizing the Fermi velocity of strained graphene from uniform to nonuniform strain