We report the formation of bound states in the continuum for Dirac-like fermions in structures composed by a trilayer graphene flake connected to nanoribbon leads. The existence of this kind of localized states can be proved by combining local densit
y of states and electronic conductance calculations. By applying a gate voltage, the bound states couple to the continuum, yielding a maximum in the electronic transmission. This feature can be exploited to identify bound states in the continuum in graphene-based structures.
The electronic transport in a system of two quantum rings side-coupled to a quantum wire is studied via a single-band tunneling tight-binding Hamiltonian. We derived analytical expressions for the conductance and spin polarization when the rings are
threaded by magnetic fluxes with Rashba spin-orbit interaction. We show that by using the Fano and Dicke effects this system can be used as an efficient spin-filter even for small spin orbit interaction and small values of magnetic flux. We compare the spin-dependent polarization of this design and the polarization obtained with one ring side coupled to a quantum ring. As a main result, we find better spin polarization capabilities as compared to the one ring design
n this article we study the Friedel phase of the electron transport in two different systems of quantum dots which exhibit bound states in the continuum (BIC). The Friedel phase jumps abruptly in the energies of the BICs, which is associated to the v
anishing width of these states, as shown by Friedrich and Wintgen in Phys. Rev. A textbf{31}, 3964 (1985). This odd behavior of the Friedel phase has consequences in the charge through the Friedel sum rule. Namely, if the energy of the BIC drops under the Fermi energy the charge changes abruptly in a unity. We show that this behavior closely relates with discontinuities in the conductance predicted for interacting quantum dot systems.
Electron tunneling through a two stage Kondo system constituted by a double quantum-dot molecule side coupled to a quantum wire, under the effect of a finite external potential is studied. We found that $I$-$V$ characteristic shows a negative differe
ntial conductance region induced by the electronic correlation. This phenomenon is a consequence of the properties of the two stage Kondo regime under the effect of an external applied potential that takes the system out of equilibrium. The problem is solved using the mean-field finite-$U$ slave-boson formalism.
We consider the electronic transport through a Rashba quantum dot coupled to ferromagnetic leads. We show that the interference of localized electron states with resonant electron states leads to the appearance of the Fano-Rashba effect. This effect
occurs due to the interference of bound levels of spin-polarized electrons with the continuum of electronic states with an opposite spin polarization. We investigate this Fano-Rashba effect as a function of the applied magnetic field and Rashba spin-orbit coupling.
In this work we address the effects on the conductance of graphene nanoribbons (GNRs) at which organic molecules are side-attached on the ribbon ends. For simplicity, only armchair (AGNRs) and zigzag (ZGNRs) nanoribbons are considered and quasi one-d
imensional molecules, such as linear poly-aromatic hydrocarbon (LPHC) and poly(para-phenylene), are chosen. The conductance of the GNRs exhibit a particular behavior as a function of the length of the organic molecules: the energy spectrum of the quasi one-dimensional system is clearly reflected in the conductance curves of the GNRs. The results suggest that GNRs can be used as an spectrograph-sensor device. An even-odd parity effect, as a function of the length of the attached molecules, can be observed in the conductance of these system. The nanostructures are described using a single-band tight binding Hamiltonian and the electronic conductance and the density of states of the systems are calculated within the Greens function formalism based on real-space renormalization techniques.
