Person:
Domínguez-Adame Acosta, Francisco

First Name

Francisco

Last Name

Domínguez-Adame Acosta

URI

https://hdl.handle.net/20.500.14352/74978

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Física de Materiales

Area

Física de la Materia Condensada

Identifiers

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Now showing 1 - 10 of 29

Quantum electron splitter based on two quantum dots attached to leads
(Physical Review B, 2006) Malyshev, Andrey; Orellana, P. A.; Domínguez-Adame Acosta, Francisco
Electronic transport properties of two quantum dots side-coupled to a quantum wire are studied by means of the two impurity Anderson Hamiltonian. The conductance is found to be a superposition of Fano and Breit-Wigner resonances as a function of the Fermi energy, when the gate voltages of the quantum dots are slightly different. Under this condition, we analyze the time evolution of a Gaussian-shaped superposition of plane waves incoming from the source lead, and found that the wave packet can be split into three packets at the drain lead. This spatial pattern manifests in a direct way the peculiarities of the conductance in energy space. We conclude that the device acts as a quantum electron splitter.
Bloch oscillations in an aperiodic one-dimensional potential
(Physical Review B, 2005) Moura, F. A. B. F., de; Lyra, M. L.; Domínguez-Adame Acosta, Francisco; Malyshev, Andrey
We study the dynamics of an electron subjected to a static uniform electric field within a one-dimensional tight-binding model with a slowly varying aperiodic potential. The unbiased model is known to support phases of localized and extended one-electron states separated by two mobility edges. We show that the electric field promotes sustained Bloch oscillations of an initial Gaussian wave packet whose amplitude reflects the bandwidth of extended states. The frequency of these oscillations exhibits unique features, such as a sensitivity to the initial wave packet position and a multimode structure for weak fields, originating from the characteristics of the underlying aperiodic potential.
Coherent electron dynamics in a two-dimensional random system with mobility edges
(Journal of physics: condensed matter, 2007) Moura, F. A. B. F., de; Lyra, M. L.; Domínguez-Adame Acosta, Francisco; Malyshev, Andrey
We study numerically the dynamics of a one-electron wavepacket in a two-dimensional random lattice with long-range correlated diagonal disorder in the presence of a uniform electric field. The time-dependent Schrodinger equation is used for this purpose. We find that the wavepacket displays Bloch-like oscillations associated with the appearance of a phase of delocalized states in the strong correlation regime. The amplitude of oscillations directly reflects the bandwidth of the phase and allows us to measure it. The oscillations reveal two main frequencies whose values are determined by the structure of the underlying potential in the vicinity of the wavepacket maximum.
Localization properties of a one-dimensional tight-binding model with nonrandom long-range intersite interactions
(Physical Review B, 2005) Moura, FABF, de; Malyshev, Andrey; Lyra, M. L.; Domínguez-Adame Acosta, Francisco
We perform both analytical and numerical studies of the one-dimensional tight-binding Hamiltonian with stochastic uncorrelated on-site energies and nonfluctuating long-range hopping integrals J(mn) = J/vertical bar m-n vertical bar(mu). It was argued recently [A. Rodriguez et al., J. Phys. A 33, L161 (2000)] that this model reveals a localization-delocalization transition with respect to the disorder magnitude provided 1 < mu < 3/2. The transition occurs at one of the band edges (the upper one for J > 0 and the lower one for J < 0). The states at the other band edge are always localized, which hints at the existence of a single mobility edge. We analyze the mobility edge and show that, although the number of delocalized states tends to infinity, they form a set of null measure in the thermodynamic limit, i.e., the mobility edge tends to the band edge. The critical magnitude of disorder for the band edge states is computed versus the interaction exponent mu by making use of the conjecture on the universality of the normalized participation number distribution at the transition.
Anderson transition in low-dimensional disordered systems driven by long-range nonrandom hopping
(Physical Review Letters, 2003) Rodriguez, A.; Malyshev, Andrey; Sierra, G.; Martín-Delgado Alcántara, Miguel Ángel; Rodriguez-Laguna, J.; Domínguez-Adame Acosta, Francisco
The single-parameter scaling hypothesis predicts the absence of delocalized states for noninteracting quasiparticles in low-dimensional disordered systems. We show analytically, using a supersymmetric method combined with a renormalization group analysis, as well as numerically that extended states may occur in the one- and two-dimensional Anderson model with a nonrandom hopping falling off as some power of the distance between sites. The different size scaling of the bare level spacing and the renormalized magnitude of the disorder seen by the quasiparticles finally results in the delocalization of states at one of the band edges of the quasiparticle energy spectrum.
Twisted graphene nanoribbons as nonlinear nanoelectronic devices
(Carbon, 2019) Saiz Bretín, Marta; Domínguez-Adame Acosta, Francisco; Malyshev, Andrey
We 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, we 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. we 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.
Numerical study of the localization length critical index in a network model of plateau-plateau transitions in the quantum hall effect
(Physical Review Letters, 2011) Amado, M.; Malyshev, Andrey; Sedrakyan, A.; Domínguez-Adame Acosta, Francisco
We calculate numerically the localization length critical index within the Chalker-Coddington model of the plateau-plateau transitions in the quantum Hall effect. We report a finite-size scaling analysis using both the traditional power-law corrections to the scaling function and the inverse logarithmic ones, which provided a more stable fit resulting in the localization length critical index v = 2.616 +/- 0.014. We observe an increase of the critical exponent v with the system size, which is possibly the origin of discrepancies with early results obtained for smaller systems.
Linear optical properties of one-dimensional Frenkel exciton systems with intersite energy correlations
(Physical Review B, 1999) Malyshev, Andrey; Rodriguez, A.; Domínguez-Adame Acosta, Francisco
We analyze the effects of intersite energy correlations on the linear optical properties of one-dimensional disordered Frenkel exciton systems. The absorption linewidth and the factor of radiative rate enhancement are studied as a function of the correlation length of the disorder. Thr absorption line width monotonously approaches the seeding degree of disorder on increasing the correlation length. On the contrary, the factor of radiative rate enhancement shows a nonmonotonous trend, indicating a complicated scenario of the exciton localization in correlated systems. The concept of coherently bound molecules is exploited to explain the numerical results, showing good agreement with theory. Some recent experiments are discussed in the light of the present theory. [S0163-1829(99)07343-9].
Bias driven coherent carrier dynamics in a two-dimensional aperiodic potential
(Physics Letters A, 2008) Moura, F. A. B. F., de; Viana, L. P.; Lyra, M. L.; Malyshev, Andrey; Domínguez-Adame Acosta, Francisco
We study the dynamics of an electron wave-packet in a two-dimensional square lattice with an aperiodic site potential in the presence of an external uniform electric field. The aperiodicity is described by epsilon(m) = V cos(pi alpha m(x)(nu x)) cos(pi alpha m(y)(nu y)) at lattice sites (m(x),m(y)), with pi alpha being a rational number, and v(x) and v(y) tunable parameters. controlling the aperiodicity. Using an exact diagonalization procedure and a finite-size scaling analysis, we show that in the weakly aperiodic regime (nu(x), nu(y) < 1), a phase of extended states emerges in the center of the band at zero field giving support to a macroscopic conductivity in the thermodynamic limit. Turning on the field gives rise to Bloch oscillations of the electron wave-packet. The spectral density of these oscillations may display a double peak structure signaling the spatial anisotropy of the potential landscape. The frequency of the oscillations can be understood using a semi-classical approach.
Bloch-like oscillations in a one-dimensional lattice with long-range correlated disorder
(Physical Review Letters, 2003) Domínguez-Adame Acosta, Francisco; Malyshev, Andrey; Moura, F. A. B. F., de; Lyra, M. L.
We study the dynamics of an electron subjected to a uniform electric field within a tight-binding model with long-range-correlated diagonal disorder. The random distribution of site energies is assumed to have a power spectrum S(k)similar to1/k(alpha) with alpha>0. de Moura and Lyra [Phys. Rev. Lett. 81, 3735 (1998)10.1103/Phys. Rev. Lett.81.3735] predicted that this model supports a phase of delocalized states at the band center, separated from localized states by two mobility edges, provided alpha>2. We find clear signatures of Bloch-like oscillations of an initial Gaussian wave packet between the two mobility edges and determine the bandwidth of extended states, in perfect agreement with the zero-field prediction.