Systems of interacting classical harmonic oscillators have received considerable attention in the last years as analog models for describing electromagnetically induced transparency (EIT) and associated phenomena. We review these models and investigate their validity for a variety of physical systems using two-and three-coupled harmonic oscillators. From the simplest EIT-Λ configuration and twocoupled single cavity modes we show that each atomic dipole-allowed transition and a single cavity mode can be represented by a damped harmonic oscillator. Thus, we have established a one-toone correspondence between the classical and quantum dynamical variables. We show the limiting conditions and the equivalent for the EIT dark state in the mechanical system. This correspondence is extended to other systems that present EIT-related phenomena. Examples of such systems are two-and three-level (cavity EIT) atoms interacting with a single mode of an optical cavity, and four-level atoms in a inverted-Y and tripod configurations. The established equivalence between the mechanical and the cavity EIT systems, presented here for the first time, has been corroborated by experimental data. The analysis of the probe response of all these systems also brings to light a physical interpretation for the expectation value of the photon annihilation operator a . We show it can be directly related to the electric susceptibility of systems, the composition of which includes a driven cavity field mode.

The interest in light-sensitive organic molecules, such as azobenzene, has increased because of their ability to functionalize two-dimensional layered systems and engineer their electronic structure. In this work, we explore the azobenzene trans and cis isomer adsorption on a molybdenum disulfide MoS2(0001) layer employing the density functional theory (DFT) within van der Waals (vdW) corrections to the semilocal exchange–correlation functional. We found that the aromatic rings of azobenzene lay parallel to the surface (two in the trans isomer and one in the cis isomer), which contributes to increasing the configuration stability by vdW interactions. Furthermore, we found a relatively large work function change upon adsorption because of the electron density rearrangement, and hence, it might affect the electronic transport properties within the single MoS2(0001) layer. We observed an increase in the relative DFT + vdW total energy among the azobenzene isomers (trans and cis) from 0.51 eV in the gas-phase (trans isomer has the lowest energy) to 0.81 eV for azobenzene supported on the MoS2(0001) surface, which can be explained by the contact of the two rings of the trans isomer directly to the surface. Thus, the binding of azobenzene on the single MoS2(0001) layer affects the isomerization process because of the relative energy increase, and this, in turn, influences the transport properties of the single MoS2(0001) layer because of the changes in the electrostatic potential.

In this work, we present a coupled experimental and theoretical first-principles investigation on one of the more promising oxide-diluted magnetic semiconductors, the Sn1−xCoxO2 nanoparticle system, in order to see the effect of cobalt doping on the physical and chemical properties.

Tuning the magnetic properties of materials is a demand of several technologies; however, our microscopic understanding of the process that drives the enhancement of those properties is still unsatisfactory. In this work, we combined experimental and theoretical techniques to investigate the handling of magnetic properties of FeCo thin films via the thickness-tuning of a gold film used as an underlayer. We grow the samples by the deposition of polycrystalline FeCo thin films on the Au underlayer at room temperature by a magnetron sputtering technique, demonstrating that the lattice parameter of the sub-20 nm thickness gold underlayer is dependent on its thickness, inducing a stress up to 3% in sub-5 nm FeCo thin films deposited over it. Thus, elastic-driven variations for the in-plane magnetic anisotropy energy, K u , up to 110% are found from our experiments. Our experimental findings are in excellent agreement with ab initio quantum chemistry calculations based on density functional theory, which helps to build up an atomistic understanding of the effects that take place in the tuning of the magnetic properties addressed in this work. The handling mechanism reported here should be applied to other magnetic films deposited on different metallic underlayers, opening possibilities for large-scale fabrication of magnetic components to be used in future devices.