Correspondence: Reply to 'On the nature of strong piezoelectricity in graphene on SiO2'

In our paper we provided an experimental evidence that the single-layer graphene (SLG) deposited on SiO 2 grating substrate exhibits very strong out-of-plane piezoelectric effect, several times greater than that of the best piezoceramics such as lead-zirconate titanate

Optical Excitations and Field Enhancement in Short Graphene Nanoribbons

The optical excitations of elongated graphene nanoflakes of finite length are investigated theoretically through quantum chemistry semi-empirical approaches. The spectra and the resulting dipole fields are analyzed, accounting in full atomistic details for quantum confinement effects, which are crucial in the nanoscale regime. We find that the optical spectra of these nanostructures are dominated at low energy by excitations with strong intensity, comprised of characteristic coherent combinations of a few single-particle transitions with comparable weight. They give rise to stationary collective oscillations of the photoexcited carrier density extending throughout the flake, and to a strong dipole and field enhancement. This behavior is robust with respect to width and length variations, thus ensuring tunability in a large frequency range. The implications for nanoantennas and other nanoplasmonic applications are discussed for realistic geometries

Graphite and Hexagonal Boron-Nitride Possess the Same Interlayer Distance. Why?

Graphite and hexagonal boron nitride (h-BN) are two prominent members of the family of layered materials possessing a hexagonal lattice. While graphite has non-polar homo-nuclear C-C intra-layer bonds, h-BN presents highly polar B-N bonds resulting in different optimal stacking modes of the two materials in bulk form. Furthermore, the static polarizabilities of the constituent atoms considerably differ from each other suggesting large differences in the dispersive component of the interlayer bonding. Despite these major differences both materials present practically identical interlayer distances. To understand this finding, a comparative study of the nature of the interlayer bonding in both materials is presented. A full lattice sum of the interactions between the partially charged atomic centers in h-BN results in vanishingly small monopolar electrostatic contributions to the interlayer binding energy. Higher order electrostatic multipoles, exchange, and short-range correlation contributions are found to be very similar in both materials and to almost completely cancel out by the Pauli repulsions at physically relevant interlayer distances resulting in a marginal effective contribution to the interlayer binding. Further analysis of the dispersive energy term reveals that despite the large differences in the individual atomic polarizabilities the hetero-atomic B-N C6 coefficient is very similar to the homo-atomic C-C coefficient in the hexagonal bulk form resulting in very similar dispersive contribution to the interlayer binding. The overall binding energy curves of both materials are thus very similar predicting practically the same interlayer distance and very similar binding energies.Comment: 18 pages, 5 figures, 2 table

Properties of Graphene: A Theoretical Perspective

In this review, we provide an in-depth description of the physics of monolayer and bilayer graphene from a theorist's perspective. We discuss the physical properties of graphene in an external magnetic field, reflecting the chiral nature of the quasiparticles near the Dirac point with a Landau level at zero energy. We address the unique integer quantum Hall effects, the role of electron correlations, and the recent observation of the fractional quantum Hall effect in the monolayer graphene. The quantum Hall effect in bilayer graphene is fundamentally different from that of a monolayer, reflecting the unique band structure of this system. The theory of transport in the absence of an external magnetic field is discussed in detail, along with the role of disorder studied in various theoretical models. We highlight the differences and similarities between monolayer and bilayer graphene, and focus on thermodynamic properties such as the compressibility, the plasmon spectra, the weak localization correction, quantum Hall effect, and optical properties. Confinement of electrons in graphene is nontrivial due to Klein tunneling. We review various theoretical and experimental studies of quantum confined structures made from graphene. The band structure of graphene nanoribbons and the role of the sublattice symmetry, edge geometry and the size of the nanoribbon on the electronic and magnetic properties are very active areas of research, and a detailed review of these topics is presented. Also, the effects of substrate interactions, adsorbed atoms, lattice defects and doping on the band structure of finite-sized graphene systems are discussed. We also include a brief description of graphane -- gapped material obtained from graphene by attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic

(Re)Inventing the Armed Forces: A Governmentality Analysis of Swedish Military Marketing and Outreach in the Era of Voluntarism

In 2010, Sweden abandoned its century-old military conscription in favour of an All-Volunteer Force (AVF). The Swedish Armed Forces (SAF) was now exposed to competition over labour, and soldiering was no longer a duty connected to male citizenship. It was a job among many. This thesis studies the SAF’s efforts to cast the military organization as an attractive employer and public authority in the era of voluntarism. The aim is to contribute insights into how the Swedish population is called upon to identify as soldiers and supporters of the armed forces in order to enable war preparations and deployments. It does so through a compilation of four research articles, each analysing different sites of military marketing and public outreach, including recruitment campaigns, social media activities and public events. The thesis shows how marketing and outreach promote the SAF as an entrepreneurial and inclusive organisation offering opportunities for personal, professional and corporal development to a wide diversity of citizens. It further demonstrates how the SAF is promoted as both a symbol and guarantor of a responsible and progressive nation/state. By reading the birth of the AVF as a form of government through freedom, this thesis problematises the liberal claim that voluntary military service symbolises a removal of power and government from the private sphere of the individual. Instead, the thesis proposes an understanding of voluntary military recruitment and marketing practices as a regulating form of power. This form of power reproduces neoliberal claims of what it means to be a productive and desirable citizen and suggests ways to achieve this enterprise through different interactions with the armed forces. Consequently, this thesis brings unique insights into efforts made by the armed forces to render war preparations and deployments not only acceptable but also attractive to the population of a liberal democracy