Garcia-Frutos E.M.,CSIC - Institute of Materials Science
Journal of Materials Chemistry C | Year: 2013
1D π-conjugated organic micro- or nanostructures keep all the advantages found in organic single crystals, e.g. high crystallinity, but without the tricky growth associated with large-sized crystals. They also present low-cost processing, solution processable materials, and large-area fabrication, and are compatible with flexible substrates. Electronic and optical properties of 1D π-conjugated organic micro- and nanomaterials can be tuned by changing their size at the central core or chemical modification of the aromatic substituents, among other alternatives. Current challenges are to find and develop an accurate control of the morphology, size, degree of uniformity, and alignment of the micro- and nanometer-sized organic single crystals, for future applications in miniaturized devices. © 2013 The Royal Society of Chemistry.
Guinea F.,CSIC - Institute of Materials Science
New Journal of Physics | Year: 2010
The intrinsic spin-orbit interactions in bilayer graphene and in graphite are studied, using a tight binding model and an intra-atomic LS coupling. The spin-orbit interactions in bilayer graphene and graphite are larger, by about one order of magnitude, than the interactions in single-layer graphene, due to the mixing of π and σ bands by interlayer hopping. Their values are in the range 0.1-1 K. The spin-orbit coupling opens a gap in bilayer graphene, and also gives rise to two edge modes. The spin-orbit couplings are largest, ∼ 1-4 K, in orthorhombic graphite, which does not have a center of inversion. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Rurali R.,Autonomous University of Barcelona |
Rurali R.,CSIC - Institute of Materials Science
Reviews of Modern Physics | Year: 2010
In this Colloquium the theory of silicon nanowires is reviewed. Nanowires with diameters below 10 nm are the focus, where quantum effects become important and the properties diverge significantly from those of bulk silicon. These wires can be treated within electronic structure simulation methods and will be among the most important functional blocks of future nanoelectronic devices. First, the structural properties of silicon nanowires are reviewed, emphasizing the close connection between the growth orientation, the cross section, and the bounding facets. Second, the electronic structure of pristine and doped nanowires is discussed, which holds the ultimate key for their applicability in novel electronic devices. Finally, transport properties are reviewed where some important limitations in the performances of nanowire-based devices can lay. Many unique properties of these systems are at the same time defying challenges and opportunities for technological advances. © 2010 The American Physical Society.
Grushin A.G.,CSIC - Institute of Materials Science
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012
In Lorentz violating quantum electrodynamics (QED) it is known that a radiatively induced Chern-Simons term appears in the effective action for the gauge field, which is finite but undetermined. This ambiguity is shown to be absent in a condensed matter realization of such a theory in Weyl semi-metals due to the existence of a full microscopic model from which this effective theory emerges. Physically observable consequences such as birefringence are also discussed in this scenario. © 2012 American Physical Society.
Nieto-Vesperinas M.,CSIC - Institute of Materials Science
Optics Letters | Year: 2015
We establish the equations for the time-averaged optical torque on dipolar bi-isotropic particles. Due to the interference of the scattered fields, it has a term additional to the one that is commonly employed in theory and experiments. Its consequences for conservation of energy, angular momentum, and effects like negative torques are discussed. © 2015 Optical Society of America.