We show that a bilayer graphene flake deposited above a ferromagnetic insulator can behave as a spin-filtering device. The ferromagnetic material induces exchange splitting in the graphene flake, and due to the Fano antiresonances occurring in the tr
ansmission of the graphene flake as a function of flake length and energy, it is possible to obtain a net spin current. This happens when an antiresonance for one spin channel coincides with a maximum transmission for the opposite spin. We propose these structures as a means to obtain spin-polarized currents and spin filters in graphene-based systems.
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.
