Marlon R. Fulla

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• PhD Physical Sciences
• Professor (Associate) at National University of Colombia

Electronic properties of a neutral donor confined in a GaAs coupled quantum dot-ring covered by a Al0.3Ga0.7As matrix were calculated using the finite element method under the effective mass and the envelope function approximations. The proposed model is set up to fit a realistic coupled quantum dot-ring geometry revealed by atomic force microscopy...

The evolution of eigenstates and related optical absorption (sum of linear and nonlinear contributions) of a singly ionized double donor (D2+) confined in InAs/GaAs (quantum-well-dot nanostructure) quantum camels were theoretically investigated. Within the effective mass and the compact density matrix approximations, the energy levels and optical a...

The electro-optical properties, i.e., the optical response in the presence of a static electric field of a \(D_2^+\) molecular complex (two charge centers interacting with a conduction band electron)confined in self-assembled GaAs/GaAlAs flake-like quantum dots were calculated. Within the effective mass approximation, the calculated results were su...

Electronic and singly ionized double donor states confined in a GaAs - AlGaAs coupled quantum dot-ring were calculated. The proposed model fits the geometry of realistic coupled quantum dot rings and allows studying the evolution of the energy spectrum as a function of the height/width of the quantum dot or ring, or the quantum ring mean radius sep...

A methodical study of the thermal properties of a hydrogen molecular ion strongly confined in a flat semiconductor quantum ring under external probes: intense laser-field radiation and static electric fields were carried out. The corresponding Schrödinger equation for these two coupled donors system was numerically solved by using the finite elemen...

The spectral features and the linear, nonlinear, and total optical absorption coefficients of two realistic $$\mathrm {GaAs/Ga}_{1-x}{\mathrm{Al}}_x{\mathrm{As}}$$ GaAs / Ga 1 - x Al x As vertically stacked V-groove quantum wires confining electronic states were theoretically studied. The compact density matrix formalism and the finite element meth...

The non-linear optical rectification (NOR), the generation of the second (SHG) and third harmonic (THG) of a singly ionized double donor (SIDD) confined in an asymmetric \(\mathrm {Ga_{1-x}Al_xAs/GaAs/ Ga_{1-y}Al_yAs}\) V-groove nanowire are theoretically calculated. The calculated energy levels exhibit a molecular-like behavior with anticrossing p...

The linear, nonlinear, and total relative refractive index change of a D+2 complex confined in a GaAs quantum ring and capped by a AlxGa1−xAs matrix, under hydrostatic pressure and magnetic fields is reported. The variations of the angle between donors allow enhancing, reducing, and even nullifying the relative refractive index change. A red-shift...

A R T I C L E I N F O Keywords: V-groove quantum wire Terahertz band Optical absorption coefficient Refractive index change A B S T R A C T The intersubband optical absorption coefficient and refractive index change of a realistic single-electron GaAs∕Ga 1−x Al x V-groove quantum wire are calculated. Finite confinement potentials and analytic model...

The present theoretical study is concerned with the behavior of a D + 2 molecular complex strongly confined in a semiconductor quantum ring under external probes: intense laser-field radiation and orthogonal electric and magnetic fields. The theoretical calculations were made using finite element method within the effective mass approximation. The...

A population balance model is applied to a steel ball mill. Experimental data were obtained for two types of balls with different chemical compositions using a marked ball test in an industrial mill of a recognized cement producer company. The balls were marked since their manufacture by an international ball supplier who guided the entire experime...

The linear and non-linear optical absorption coefficients of a D2+ artificial molecule confined in GaAs nano-scaled rings under a threading magnetic field were calculated. The results showed that by varying the position and the angle formed by the double-donor system, the total optical absorption can be enhanced, quenched, or even totally nullified...

This paper presents the results of the characterization of alumina ball size distribution in the mill of a crushing and grinding plant. The mill was unloaded and the balls were sieved. Then, the results were adjusted to three kinds of models; two of them are the traditional models of Rosin-Rammler and Gates-Gaudin-Schumann. The third model applied...

The non-linear rectification and generation of the second and third harmonic of a realistic single-electron Ga1−yAlyAs/GaAs/Ga1−xAlxAs V-groove quantum wire are calculated. The effects of the V-groove geometrical and physical parameters, such as the inter-sidewall angle, the thickness of the crescent, the position of the pinch-offs, the temperature...

Ceramic materials such as calcium phosphates (CaPs) with a composition similar to the mineral phase of bones and polymeric polylactic acid (PLA) are potential candidates for the manufacturing of scaffolds to act as bone substitutes and for tissue engineering applications, due to their bioresorbability and biocompatibility. Variables such as porosit...

The low-lying energy levels of two on-axis shallow donor impurities releasing two electrons in two vertically stacked Ga1−xAlxAs nanorings are calculated. The analysis has been focused on the effects of the hydrostatic pressure (P), aluminum concentration (x) and temperature (T) in the quantum energy levels ordering. These variables affect the leve...

A study of the evolution of the eigenstates of a conduction band electron confined in a GaAs/Ga1−xAsAlx V-groove quantum wire under an electric field was carried out. The eigenstates were calculated as a function of aluminum concentration, the crescent thickness and its curvature, the wire's width, and the position and geometry of the pinch-offs by...

The results of characterizing the alumina ball size distribution in two mills of a crushing and grinding plant are shown. The mills were unloaded and the ball charge was screened in order to establish the ball size distribution. For both mills, the balls retained during the unloading were compared to the balls retained at the beginning of the proce...

A general and realistic population balance model is applied to a ceramic ball mill. The experimental data are obtained for three differently sized balls. The mill is operated 500 h with silica sand during 8 cycles. After each cycle, the mill is stopped to measure the ball wear to obtain the kinetics wear equations. It turns out that the wear law fo...

Numerical calculations of an off-axis donor in a quantum ribbon under the presence of crossed electric and magnetic fields were performed. A particular ribbon with non-uniform height and very large base radius-to-height aspect ratio was considered. The corresponding Schrödinger equation has been solved by using adiabatic and exact diagonalization p...

The eigenstates of a hydrogenic complex confined in a washer-shaped quantum ring with lateral position-controllable protuberances with a Gaussian aspect under the presence of crossed magnetic and electric probes were calculated. The size and position of the protuberances affect significantly the degree of the electron localization observable in Aha...

The neutral donor energy structure in non-uniform height quantum strip under the presence of crossed electric and magnetic fields is studied. The quantum strip height has been modeled by including a phenomenological two-parametric function. The first of these parameters is related to the number of structural hills present on the nano-strip, while t...

En numerosos problemas de la mecánica estadística aplicada, como es el caso de los fenómenos de ransporte, las denominadas derivadas bajo la integral han sido una herramienta importante e interesante de explotar, ya que en el estudio de sistemas ingenieriles, es posible realizar una caracterización de su comportamiento y conocer sus propiedades mós...

Un modelo simple basado en la aproximación adiabática, se ha implementado para estudiar el espectro energético de una molécula de hidrógeno confinada en un anillo cuántico muy estrecho. El sistema completo se encuentra bajo la influencia de campos externos: magnético y de presión hidrostática. Los resultados muestran la posibilidad de obtener moléc...

El conocimiento del tamaño de partículas del orden de las micras o los nanómetros en suspensiones, ofrece una gran cantidad de información para un amplio rango de aplicaciones biológicas y biomédicas tales como el desarrollo de biopolímeros, evaluación de la eficiencia de antibióticos y medicamentos contra el cáncer. En estas investigaciones se tie...

Single electron and off-axis neutral donor in non-uniform height quantum ribbon under threading external magnetic field is analyzed. The quantum ribbon height dependence with polar angle is modeled trough the two-parametric function. One of these parameters define the number of protuberances and the other one allows us to exert control on the struc...

Keywords: Two-electron quantum dots Anisotropic parabolic confinement Ellipsoidal and elliptical quantum dots We analyze the spectrum of two-electron quantum dot with anisotropic parabolic confinement by using the fractional-dimension formulation which allows us to reduce the two-particle problem to two equations for independent particles in an eff...

The combined effects of hydrostatic pressure, temperature, and aluminum concentration on the binding and total energies of two coupled donors are analyzed using a variational procedure. The effects of changing the nucleus–nucleus relative positions and the quantum well size on the complex binding energy were also analyzed. The results show that an...

Two-electron energy levels in coupled nano-rings: the hydrostatic pressure and magnetic field effects Niveles energéticos bi-electrónicos en nano-anillos acoplados: Efectos de la presión hidrostática y del campo magnético Abstract The energy spectrum of two electrons spatially separated in two vertically coupled quantum rings under hydrostatic pres...

The energy structure of a D -ion, that is two electrons bound to a fixed donor impurity, imprisoned in a toroidal quantum ring is calculated as the full system is simultaneously under the presence of hydrostatic pressure probe and threading magnetic field. With the purpose of studying the D -energy properties; we have assumed very narrow quantum ri...

A model for an artificial hydrogen molecule consisting of two positive on-axis Coulombic centers and two electrons coupled to them inside a double concentric quantum ring is considered. Such a nanostructure is assumed to be under the influence of external probes like hydrostatic pressure and magnetic field. By using the adiabatic approximation, the...

In this work we investigate the energy states in a D + 2 complex formed by the coupling of a conduction band electron and two donor centers in a quantum ring with rectangular cross-section. The inuences of externally applied probes like electric and magnetic elds and hydrostatic pressure together with the change in the relative position between the...

In this work we investigate the energy states in a D+2 complex formed by the coupling of a conduction band electron and two donor centers in a quantum ring with rectangular cross-section. The influences of externally applied probes like electric and magnetic fields and hydrostatic pressure together with the change in the relative position between t...

En el presente trabajo se evalúa la viabilidad de implementar la tecnología XBee en el desarrollo de sensores acelerométricos inalámbricos (SAI) para el registro en superfi-cie de las vibraciones que generan las ondas sísmicas que se propagan en el suelo. Se verificó experimentalmente la incidencia de la distancia y de la presencia de obstáculos en...

Mediante el uso de un modelo simple basado en la aproximación adiabática, es posible determinar las características más sobresalientes de una molécula diatómica homonuclear alineada entre dos anillos cuánticos concéntricos. La molécula también se encuentra inmersa bajo el efecto combinado de los campos externos y uniformes magnéticos y de presión h...

Este trabajo presenta el estado del arte y propone una metodología a desarrollar en el uso de ondas sísmicas para prospección de subsuelos con énfasis en la detección de discontinuidades físicas a baja profundidad. Esta actividad es el centro de atención de importantes áreas de la nación, como es el caso de la minería, la geología, la construcción...

We study the energy spectrum of two-electron constrained to move in two concentrically quantum ribbons under a homo-geneous magnetic field oriented along the common symmetry axis. By using the center of mass and relative coordinates, we obtain a second order one-dimensional equation which is numerically solved by means of the trigonometric sweep me...

Se han analizado los efectos de correlación espacial para dos electrones acoplados electrostáticamente en dos anillos muy estrechos con diferentes radios apilados verticalmente. Se han encontrado y analizado los niveles de energía como función de la razón entre los radios de los anillos, la distancia entre anillos y el campo magnético aplicado a lo...

The energy spectrum of two electrons spatially separated in two toroidal and vertically stacked narrow nanorings with different radii has been analyzed by using a very simple model based on the adiabatic approximation. The low-lying energy levels are found to be a function of the ratio between the ring centreline radii and the magnetic field. Our r...

A model of an artificial hydrogen molecule consisting of two on-axis ionized donors and two electrons furnished by them inside a narrow quantum ring under the presence of an external magnetic field is considered. By using the adiabatic approximation, the lowest-energy states as a function of the separation between donors are calculated and compared...

An artificial hydrogen molecule consisting of two electrons released by two on-axis donors into a two-dimensional quantum ring with a very small width is analyzed. The two donors are located at different positions respect to symmetry center. The molecular complex is in presence of an uniform magnetic field which is oriented along the donor axis. Fo...