Jorge Quereda and Pedro L. Alcázar have been working hard to assemble the laboratory instruments for optical characterization of materiales and recorded the first optical spectra of MoS2. The tests went smooth and steady and here is the proof.



Congratulations and all the best in your reasearch !

In a recent paper [Carbon 149, 587 (2019)], M. Saiz-Bretín et al argue that twisted graphene nanoribbons subjected to a transverse electric field can operate as a variety of nonlinear nanoelectronic devices with tunable current-voltage characteristics controlled by the transverse field. Using the density-functional tight-binding method to address the effects of mechanical strain induced by the twisting, they show that the electronic transport properties remain almost unaffected by the strain in relevant cases and propose an efficient simplified tight-binding model which gives reliable results. The transverse electric field creates a periodic electrostatic potential along the nanoribbon, resulting in a formation of a superlattice-like energy band structure and giving rise to different remarkable electronic properties. They demonstrate that if the nanoribbon geometry and operating point are selected appropriately, the system can function as a field-effect transistor or a device with nonlinear current-voltage characteristic manifesting one or several regions of negative differential resistance. The latter opens possibilities for applications such as an active element of amplifiers, generators, and new class of nanoscale devices with multiple logic states.

In a recent paper [Physical Review B 95, 165428 (2019)], M. Saiz-Bretín et al argue that graphene nanorings attached to two leads show increased phonon scattering while keeping good electron transport. Using a density-functional parametrized tight-binding method combined with Green’s function technique, they show that the lattice thermal conductance is largely reduced as compared to that of graphene nanoribbons. At the same time, numerical calculations based on the quantum transmission boundary method, combined with an effective transfer matrix method, predict that the electric properties are not considerably deteriorated, leading to an overall remarkable thermoelectric efficiency. They conclude that graphene nanorings can be regarded as promising candidates for nanoscale thermoelectric devices.

In a recent paper [Physical Review E 98, 052221 (2018)], E. Díaz et al introduce an effective model for electron transport in a deformable helical molecular lattice that resembles the nonlinear Kronig-Penney model in the adiabatic approximation. In addition, the continuum limit of the model is achieved when the dipole-dipole distance is smaller than the spatial extent of the bright soliton, as discussed by E. Díaz et al. [N. J. Phys. 20, 043055 (2018)]. In this limit, the model reduces to an extended Davydov model. Finally, they also focus on perturbations to the bright soliton that arise naturally in the context of real helical molecules. They conclude that the continuum approximation provides excellent results in more complex scenarios.

In a recent paper [Journal of Physics: Condensed Matter 32, 275301 (2020)], C. Núñez et al present a thorough study of the thermoelectric properties of silicene nanoribbons in the presence of a random distribution of atomic vacancies. By using a linear approach within the Landauer formalism, they calculate phonon and electron thermal conductances, the electric conductance, the Seebeck coefficient and the figure of merit of the nanoribbons. They found a sizable reduction of the phonon thermal conductance as a function of the vacancy concentration over a wide range of temperature. At the same time, the electric properties are not severely deteriorated, leading to an overall remarkable thermoelectric efficiency. They conclude that the incorporation of vacancies paves the way for designing better and more efficient nanoscale thermoelectric devices.