# Jose Jose Barba OrtegaNational University of Colombia | UNAL · Departamento de Física (Bogotá)

Jose Jose Barba Ortega

PhD en Fisica

## About

180

Publications

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793

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Introduction

Superconductivity, Ginzburg-Landau theory, condensed matter

Additional affiliations

February 2010 - present

January 2009 - present

June 2007 - June 2009

## Publications

Publications (180)

Resumen En este trabajo se estudió el estado resistivo de una muestra superconductora mesoscópica en presencia de una corriente de transporte J a , y a campo magnético nulo. Un canal no centrado de superconductividad depreciada (de ancho m y temperatura crítica más baja T c) se ubicó a una distancia d del centro de la muestra. Variamos el ancho a d...

In this paper, we investigate the electronic and superconducting properties in nicke-late compounds of NiO 2 through perturbative density functional theory (P-DFT) and extended multi-band Bardeen-Cooper-Schrieffer (BCS) theory. We consider four different cases of study: (i) the crystalline structure composed by one layers of NiO 2 , with a central...

An analytical development is proposed to determine the solution of the motion equations of a charged particle under the infl uence of an electric fi eld. In the proposal, the advantages and properties of Laplace's transformation are used to map a system of N second-order non-homogeneous diff erential equations into a system composed of N linear equ...

In the present work, we will study the superconducting properties of a mesoscopic three-dimensional prism with square transversal section under an external magnetic field in both Zero-Field Cooling (ZFC) and Field-Cooling (FC) process. The studied sample is a three-band system (with three condensates ψ1, ψ2, ψ3), in which we take a Josephson type i...

In the present work, we studied the magnetization, vorticity, Cooper pairs density, and the spatial distribution of the local magnetic field in a three-dimensional superconductor with a SQUID geometry (a square with a central hole connected to the outside vacuum through a very thin slit). Our investigation was carried out in both the Meissner-Osche...

En el presente artículo se exploran diversas técnicas de optimización a través de metodologías diferentes; es importante resaltar que los problemas de optimización se encuentran en una gran multitud de disciplinas académicas, y los caminos propuestos para resolverlos se encuentran, el primero, en las técnicas matemáticas denominadas fuertes (óptimo...

In the present work we study a magnetic nano-wire systems composed of finite layers, forming a nano-bulk. The interaction between the layers (inter-layers) is given by an exchange term J and the interactions within each layer (intra-layer) are given by a magneto-static interaction energy between the nano-wires. We propose to create a geometrical pa...

Abstract In the present research, the synthesis of cobalt oxide Co3O4 was carried out using the sol-gel technique with subsequent heat treatment at 225 and 235 °C. The final product obtained was characterized by X-ray diffraction (XRD), showing a pure crystalline phase of Co3O4, cell parameters a=b=c=8.071 Å, and a volume of 525.7 Å3. The particle...

Our study sample is a superconducting bi-dimensional octagon with different boundary conditions immersed in a magnetic external field H. The boundary conditions are simulated by considering different values of the deGennes extrapolation length b on different surfaces of the sample. Our investigation was carried out by solving the time dependent Gin...

In this work, the dynamic model of the synchronous motor was analyzed, which has a typical structure of Lienard-type systems. For this, the theory of dynamic systems was used, especially the Hopf bifurcation. The objective is to apply this type of bifurcation to the model described in order to show the variations in the equilibrium points of the sy...

En esta contribución estudiamos el estado de vórtices en una muestra cuadrada superconductora de dos orbitales en presencia de un campo magnético externo H constante en un proceso de zero-field-cooling. La muestra está en contacto con diferentes tipos de materiales simulados a través del parámetro de extrapolación de deGennes (b) . Nuestra investig...

The reciprocal contribution that physics has had in engineering and engineering in physics is undeniable. The First International Conference on Physical Problems of Engineering (1st ICPPE) tries to highlight this symbiotic relationship between both sciences through different presentations that reflected their results in separate articles that will...

In this research, the concentration-depth profiles reached by titanium and nitrogen particles, on the surface of AISI/SAE 1020 carbon steel substrates, by using of ion implantation technique, are studied. The ions are surface deposited by means of high voltage pulsed discharges and electric arc discharge under high vacuum conditions. The concentrat...

In the present work, we will study the effect of dimensionality (i.e 2 + 1 and 3 + 1) has on the different types of coupling in a two-band superconducting system, specifically for the Josephson, bi-quadratic and weak type couplings. This study will be oriented to a ZFC (Zero-Field-Cooling) process and we will see the effect that the variation of te...

In the present work, we will study the effect that the surface roughness of the sample has on the magnetic and thermodynamic properties in a mesoscopic superconducting meso-square under an external magnetic field in a Zero field cooling process. We will analyze the mag-netization, superconducting electronic density, free Gibbs energy, specific heat...

In this work, we studied the change in the electric current and the length of the nanotubes depending on the area and the exposure time in the anodizing process. Over time the anodizing area was changed with a rate of 0.5 cm2 to 2.5 cm2 using a total anodizing time of 60 min, using a chemical solution (2ml /3 ml /0.30g ) and maintaining a constant...

We solve the two-band Ginzburg-Landau equations for a superconducting mesoscopic prism for a condensate characterized by two order parameters (ψ1,ψ2). We study the effect of the phase and γ˜ differences on the vortex state, magnetization, magnetic susceptibility (χm), vortex localization, and vorticity for boths condensate. Finally, we present show...

We studied the (magnetic field-temperature) phase diagram, the resistive state and the vortex configurations of a rectangular superconducting loop, under an electrical transport current, J, and an external applied magnetic field H. We show that the critical current density in the I-V characteristic curve J c1 , at which the first vortex-antivortex...

In the present work, we studied the effect that the dimensionality (2+1 and 3+1), the type of couplings (Josephson, bi-quadratic and weak), and the temperature of the sample, have on the superconducting electronic density, magnetization and Gibbs free energy of a two-band superconducting system. This study was oriented to a Zero-Field-Cooling (ZFC)...

Our study sample is a mesoscopic superconducting three-dimensional parallelepiped immersed in a magnetic field H z. The sample presents a anisotropy of the Ginzburg-Landau parameter κ(z) in the z axis. This dependence allow us to simulate a superconducting three-layer, where the top and botton layers are made of a type-II superconducting material a...

This paper shows the effect of the Josephson and bi-quadratic coupling types on the vortex state, the magnetization in a two-band superconducting disk in the presence of an external magnetic field and the effect that the value has on the vortex state. This study is based on the two bands Ginzburg-Landau time dependent theory, and the main propertie...

We demonstrate that the presence of edges in a superconducting film made of a Type-I/Type-II bilayer stabilizes Type-II/Type-I hybrid ({\it inter-type}) flux patterns, as vortex clusters, chains, and gel phase. These patterns are very sensitive to primary parameters such as applied magnetic field, layer coupling, and temperature. Thus, the magnetiz...

We analyzed the role of the inclusion of anti-dots on the vortex state and some calorimet-
ric properties of a mesoscopic superconducting square immersed in an external applied
magnetic field. We calculated the magnetization, entropy, Gibbs free energy, density of
Cooper pairs and specific heat for this system in a zero field cooling process, solvi...

In this contribution, we show the implementation of the Link-variable method for solve the complete set of acopled non-linear time dependent Ginzburg-Landau differential equations in a three-dimensional homogeneous and isotropic mesoscopic superconducting system. In this case, the sample is immersed in an external magnetic d at zero applied current...

In this paper, we studied the power dissipation process of a Shubnikov vortex-antivortex pair in a mesoscopic superconducting square sample with a concentric square defect in presence of an oscillatory external magnetic field. The time-dependent Ginzburg-Landau equations and the diffusion equation were numerically solved. The significant result is...

Agglomerates of Co3O4 were obtained using the sol–gel method for the synthesis with subsequent calcination of the samples up to 550 °C. Through X-rays it was observed that the samples presented the pure spinel phase with a crystallite size between 33.73 and 41.45 nm. In the thermogravimetric measurement from 262 °C high structural stability is pres...

In this paper, we studied the power dissipative process of a Shubnikov vortex-antivortex pair in a mesoscopic superconducting square sample with a concentric square defect in presence of an oscilatory external magnetic field. The extended time-dependent Ginzburg-Landau equations were numerically solved. The significant result is that the thermal di...

We studied the influences of the inclusion of different geometrical defects (circle, triangle, and square) with different Ginzburg-Landau parameters κ on the vortex state of a mesoscopic superconducting square immersed in an external applied magnetic field. We calculated the magnetization, vor-ticity, and density of Cooper pairs for this system, so...

This contribution presents optimal control over a double extractor induction motor using formalism through variational model. The criterion is subject to non-stationary equations of a reduced order (Dynamics equations of a reduced order model (DSIM)). As is well know, in this model the state variables are the rotor flow and motor speed in a circuit...

In the present work we studied the effect of the nature of the contacts, by which a weak external current is applied, in an anisotropic superconducting rectangle, on the magnetization, magnetic susceptibility, density of the Cooper pairs and (magnetic field for which the first vortices entry on the sample). The contacts are simulates by the paramet...

We present the influence of the deGennes extrapolation length on the vortex matter in a two band superconducting square with a central defect. This is determined by considering different values of the de Gennes extrapolation length b on the lateral surface of the sample. Our investigation was carried out by solving the two-dimensional time-dependen...

Using Ginzburg–Landau simulations, we study the effect of a multigeometric modulation of the superconducting condensate, imposed by the spatially nanoengineered critical temperature Tc inside a mesoscopic superconductor. A plethora of intriguing vortex states is reported in the presence of the applied magnetic field, reflecting the rich interplay o...

Una matriz tubular de TiO2/Ti obtenida por el método de anodización electroquímica fue usada como sustrato para el depósito de una única camada de CuO (oxido de cobre) o CuO dopado con Fe al 1% por el método de spin coating. En los métodos de anodizado se usaron dos tiempos diferentes de 40 y 60 minutos respectivamente. En la obtención de la estruc...

En este trabajo aplicamos la teoría Ginzburg-Landau dependiente del tiempo (TDGL) para calcular la magnetización M(H), la configuración de vórtices y la densidad de corriente de muestras mesoscópicas en materiales superconductores sometidos a diferentes gradientes lineales de temperatura. Resolvemos las TDGL en una película delgada cuadrada, inmers...

In the present work we analyze the effect of topological defects at different temperatures in a mesoscopic superconducting sample in the presence of an applied magnetic field H. The time-dependent Ginzburg-Landau equations are solved with the method of link variables. We study the magnetization curves M(H), number of vortices N(H) and Gibbs G(H) fr...

In the framework of the time depedente Ginzburg-Landau theory, we analyzed the vortex matter in a superconducting square with a dice structure of circular anti-dots generates by a variable heat source. We solved numerically the time-dependent-Ginzburg-Landau equations (TDGL) to describe the effect of the temperature of the circular defects on the a...

We study the superconducting state of a strip under an transport current $\vec {J_{a}}$ and an external magnetic field $\vec{H}$. We show that the value of the critical currents at which the vortex-antivortex (\textit{V-Av}) pair penetrates the sample, the number of phase-slip lines, and their average velocities and dynamics strongly depend on the...

α-Fe2O3 samples were manufactured by means of the polymeric precursor method. The powders were sintered and calcined at temperatures of 300–700 °C for 2 h, respectively. In the X-ray diffraction results, the formation of the rhombohedral phase without secondary phases was exhibited. The size of the particle increased after calcination at 700 °C, ex...

In this work we study the deformations and extension of the Ginzburg-Landau theory for the superconductor state. We will explain the history, advances, applications, future prospects and the numerical methods used to solve the time dependent Ginzburg-Landau Equations (TDGL). Also we will study more complex systems such as the superconductors with e...

We show a possible relationship between the deformation factor τ and the inverse of the deGennes parameter γ in the Ginzburg Landau model for a superconducting meso-film and meso-disk in the presence of an external magnetic field in the Meissner state. It is shown that there is a lineal relationship between τ and γ when a forced model is considered...

Maintaining a constant voltage the growth of titanium oxide (T iO 2) with a tubular geometry was studied. Therefore, the optimal parameters for the growth of TiO 2 were established using an organic electrolytic solution with a total volume of 150ml, composed of water/hydrofluoric acid/ammonium fluoride/ethylene glycol. The anodization conditions we...

An analytical analysis to obtain the time dependent Ginzburg-Landau equations in presence of a current J and magnetic
field H in a mesoscopic superconducting thin film is shown. The transport current is applied in a little contact in the
boundary of the sample. This contacts are included through to the deGennes extrapolation parameter b in the boun...

We study the resistive state of a mesoscopic superconducting strip with an engineered defect at the center. The defect is another superconductor with a different critical temperature. Several geometrical shapes of the defect are studied. The strip is considered under a transport electrical current, Ja, and at zero external applied magnetic field. T...

RESUMEN En este trabajo se presenta un estudio comparativo de tres métodos en la obtención de muestras a bajo costo. Las muestras obtenidas son nanopaticulas de óxido de Hierro, óxido de Cobre y nanotubos de Titanio. Las dos primeras fueron obtenidas por el método Sol-Gel, precursores poliméricos y la tercera muestra por el método de anodización qu...

The Time-dependent Ginzburg–Landau model (TDGLM) is a robust tool widely used to analyze the magnetization of the single-vortex state of a mesoscopic superconducting sample in presence of a magnetic field. The algorithm implemented in this work is ap- plied to a square geometry surrounded by different kinds of materials simulated by de- Gennes extr...

In the present contribution, we show how the inclusion of a structural defect of determined geometry controls the vortex state in a superconducting square sample in presence of a external magnetic field and a $dc$ current. We simulated the defects by the deformation parameter $\tau(x,y)$ solving the non-lineal time dependent Ginzburg-Landau equatio...

We study the behavior that the inclusion of zones with different Ginzburg-Landau parameters κ has on the magnetization, Cooper pair density , and H 1 , the magnetic field in which the first vortex penetration occurs, in a superconducting 2D square in the presence of an external applied magnetic field H. We report anomalous vortex configurations and...

Gibbs free energy, vorticity, magnetization and Abrikosov state in a nanoscopic superconducting square in the presence of an external magnetic field and a heat source produced by a laser with lateral incidence on the sample, are studied. We solved computationally the time-dependent Ginzburg–Landau (TDGL) equations to describe the effect of the heat...

In this work a study of the effect of the synthesis conditions on the vibratory and particle size properties in the cupric oxide (CuO) has been presented. The synthesis has been carried out by the polymeric precursor method without modifying the PH in the process, this being a low cost method. The samples obtained have been subjected to several cal...

We consider a mesoscopic superconducting three-dimensional cube immersed in a tilted magnetic field H oriented along an angle θ with respect to the z-axis, in the xz plane. The sample is in contact with a metallic material or with another superconductor in the xz and yz planes, while the z=0 plane remains in contact with a dielectric material. Thes...

We study the superconducting state of a thin film at zero external applied magnetic field under a transport electric current, J a . By taking into account the roughness percentage of its surface R, we show that the value of J a =J c1 at which the first vortex-antivortex (V-Av) pair penetrates the sample, the superconducting-normal transition curren...

Resumen La solución en mecánica cuántica para sistemas en el cual el operador de Hamilton no depende del tiempo (Estados estacionarios), se centra en la solución de la ecuación de Schrödinger independiente del tiempo. Sin embargo, cuando el sistema se transforma en un sistema con muchas partículas, la solución de la ecuación no se puede abordar por...