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Optical properties of (In,Ga)As capped InAs quantum dots grown on [11k] substratesApr 18 2007Using three-dimensional k.p calculation including strain and piezoelectricity, we showed that the size of the quantum dot (QD) in the growth direction determines the influence of the (In,Ga)As capping layer on the optical properties of [11k] grown InAs ... More

Dynamic response of artificial bipolar moleculesMar 27 2002We calculate the equilibrium properties and the dynamic response of two vertically coupled circular quantum dots populated by particles of different electrical charge sign, i.e. electrons and holes. The equilibrium density profiles are obtained and used ... More

Classical artificial two-dimensional atoms: the Thomson modelNov 01 1996The ring configurations for classical two-dimensional atoms are calculated within the Thomson model and compared with the results from `exact' numerical simulations. The influence of the functional form of the confinement potential and the repulsive interaction ... More

A three-dimensional model for artificial atoms and molecules: Influence of substrate orientation and magnetic field dependenceMar 27 2007A full three-dimensional model for the calculation of the electronic structure of semiconductor quantum dots (QD) and molecules (QDM) grown on high index surfaces and/or in the presence of an external magnetic field is presented. The strain distribution ... More

Re-entrant pinning of Wigner molecules in a magnetic field due to a Coulomb impurityMay 05 2004Pinning of magnetic-field induced Wigner molecules (WMs) confined in parabolic two-dimensional quantum dots by a charged defect is studied by an exact diagonalization approach. We found a re-entrant pinning of the WMs as function of the magnetic field, ... More

Snake orbits and related magnetic edge statesFeb 24 2000We study the electron motion near magnetic field steps at which the strength and/or sign of the magnetic field changes. The energy spectrum for such systems is found and the electron states (bound and scattered) are compared with their corresponding classical ... More

Wigner crystallization in quantum electron bilayersDec 31 1996The phase diagram of quantum electron bilayers in zero magnetic field is obtained using density functional theory. For large electron densities the system is in the liquid phase, while for smaller densities the liquid may freeze (Wigner crystallization) ... More

Wigner crystallization in the two electron quantum dotMay 18 2000Wigner crystallization can be induced in a quantum dot by increasing the effective electron-electron interaction through a decrease of the electron density or by the application of a strong magnetic field. We show that the ground state in both cases is ... More

Correlated few-particle states in artificial bipolar moleculeMar 22 2002We investigate the ground and excited states of a bipolar artificial molecule composed of two vertically coupled quantum dots containing different type of carriers -- electrons and holes -- in equilibrium. The approach based on exact diagonalization is ... More

Few-electron eigenstates of concentric double quantum ringsSep 22 2005Few-electron eigenstates confined in coupled concentric double quantum rings are studied by the exact diagonalization technique. We show that the magnetic field suppresses the tunnel coupling between the rings localizing the single-electron states in ... More

Time dependent simulations of electron transport through a quantum ring: effect of the Lorentz forceMar 11 2005Oct 28 2005The time dependent Schr\"odinger equation for an electron passing through a semiconductor quantum ring of nonzero width is solved in the presence of a perpendicular homogenous magnetic field. We study the effects of the Lorentz force on the Aharonov-Bohm ... More

Resistance effects due to magnetic guiding orbitsSep 20 2000The Hall and magnetoresistance of a two dimensional electron gas subjected to a magnetic field barrier parallel to the current direction is studied as function of the applied perpendicular magnetic field. The recent experimental results of Nogaret {\em ... More

Controllable spin singlet - spin triplet transition in three concentric quantum rings through magnetic field and confinement potentialApr 13 2012We present a theoretical study of the spectrum of electrons confined in triple concentric rings. An unusual ordering and rich variety of angular momentum transitions are found that depend on the coupling between the rings and the confinement potential ... More

Stability, dynamical properties and melting of a classical bi-layer Wigner CrystalNov 15 1995We investigate the stability, the dynamical properties and melting of a two-dimensional (2D) Wigner crystal (WC) of classical Coulombic particles in a bi-layer structure. Compared to the single-layer WC, this system shows a rich phase diagram. Five different ... More

Quantum dot size dependent influence of the substrate orientation on the electronic and optical properties of InAs/GaAs quantum dotsSep 14 2006Using 3D k.p calculation including strain and piezoelectricity we predict variation of electronic and optical properties of InAs/GaAs quantum dots (QDs) with the substrate orientation. The QD transition energies are obtained for high index substrates ... More

Semi-classical magnetoresistance in weakly modulated magnetic fieldsJan 25 2000The semi-classical conductance of a two-dimensional electron gas is calculated in the presence of a one-dimensional modulated magnetic field with zero average. In the limit of small magnetic field amplitudes (B) the contribution of the magnetic modulation ... More

Enhanced Weiss oscillations in grapheneJan 09 2007The magneto-conductivity of a single graphene layer where the electrons are described by the Dirac Hamiltonian weakly modulated by a periodic potential is calculated. It is shown that Weiss oscillations periodic in the inverse magnetic field appear, that ... More

Tunable optical Aharonov-Bohm effect in a semiconductor quantum ringApr 13 2012By applying an electric field perpendicular to a semiconductor quantum ring we show that it is possible to modify the single particle wave function between quantum dot (QD)-like to ring-like. The constraints on the geometrical parameters of the quantum ... More

Quasi-bound states of quantum dots in single and bilayer grapheneNov 28 2007Dirac fermions interacting with a cylindrically symmetric quantum dot potential created in single and bilayer graphene are not confined but form quasi-bound states. The broadening of these quasi-bound states (i. e. the inverse of their lifetimes) decreases ... More

Pinning and depinning of a classic quasi-one-dimensional Wigner crystal in the presence of a constrictionNov 09 2005We studied the dynamics of a quasi-one-dimensional chain-like system of charged particles at low temperature, interacting through a screened Coulomb potential in the presence of a local constriction. The response of the system when an external electric ... More

Plasmon and dielectric background inhomogeneity enhancement of Coulomb drag in graphene double-layer structuresApr 20 2012The drag of massless fermions in graphene double-layer structures is investigated in a wide rage of temperatures and inter-layer separations. We show that the inhomogeneity of the dielectric background in such graphene structures for experimentally relevant ... More

Lattice thermal properties of Graphane: thermal contraction, roughness and heat capacityMay 12 2011Using atomistic simulations we determine the roughness and the thermal properties of a suspended graphane sheet. As compared to graphene we found that hydrogenated graphene has: 1) a larger thermal contraction, 2) the roughness exponent at room temperature ... More

Graphene nano ribbons subjected to axial stressApr 09 2011Atomistic simulations are used to study the bending of rectangular graphene nano ribbons subjected to axial stress both for free boundary and supported boundary conditions. The shape of the deformations of the buckled graphene nano ribbons, for small ... More

Effect of nonhomogenous dielectric background on the plasmon modes in graphene double-layer structures at finite temperaturesDec 26 2011Dec 14 2013We have calculated the plasmon modes in graphene double layer structures at finite temperatures, taking into account the inhomogeneity of the dielectric background of the system. The effective dielectric function is obtained from the solution of the Poisson ... More

The interaction between a superconducting vortex and an out-of-plane magnetized ferromagnetic disk: influence of the magnet geometryMar 17 2003The interaction between a superconducting vortex in a type II superconducting film (SC) and a ferromagnet (FM) with out-of-plane magnetization is investigated theoretically within the London approximation. The dependence of the interaction energy on the ... More

Superconducting Wigner Vortex Molecule near a Magnetic DiskNov 25 2002Within the non-linear Ginzburg-Landau (GL) theory, we investigate the vortex structure in a superconducting thin film with a ferromagnetic disk on top of it. Antivortices are stabilized in shells around a central core of vortices (or a giant-vortex) with ... More

Single-layer and bilayer graphene superlattices: collimation, additional Dirac points and Dirac linesJan 21 2011We review the energy spectrum and transport properties of several types of one- dimensional superlattices (SLs) on single-layer and bilayer graphene. In single-layer graphene, for certain SL parameters an electron beam incident on a SL is highly collimated. ... More

Extra Dirac points in the energy spectrum for superlattices on single-layer grapheneFeb 07 2010We investigate the emergence of extra Dirac points in the electronic structure of a periodically spaced barrier system, i.e., a superlattice, on single-layer graphene, using a Dirac-type Hamiltonian. Using square barriers allows us to find analytic expressions ... More

Graphene on hexagonal lattice substrate: Stress and Pseudo-magnetic fieldJul 04 2014Moir'e patterns in the pseudo-magnetic field and in the strain profile of graphene (GE) when put on top of a hexagonal lattice substrate are predicted from elasticity theory. %which are confirmed by atomistic simulations. The van der Waals (vdW) interaction ... More

Energy-Momentum dispersion relation of plasmarons in bilayer grapheneOct 23 2013The relation between the energy and momentum of plasmarons in bilayer graphene is investigated within the Overhauser approach, where the electron-plasmon interaction is described as a field theoretical problem. We find that the Dirac-like spectrum is ... More

Buckled circular monolayer graphene: a graphene nano-bowlDec 23 2010We investigate the stability of circular monolayer graphene subjected to a radial load using non-equilibrium molecular dynamics simulations. When monolayer graphene is radially stressed, after some small circular strain ($\sim 0.4%$) it buckles and bends ... More

Confined states in two-dimensional flat elliptic quantum dots and elliptic quantum wiresJul 16 2001Jul 23 2001The energy spectrum and corresponding wave functions of a flat quantum dot with elliptic symmetry are obtained exactly. A detailed study is made of the effect of ellipticity on the energy levels and the corresponding wave functions. The analytical behavior ... More

Landau levels and magnetopolaron effect in dilute GaAs:NMay 09 2010The magnetic-field dependence of the energy spectrum of GaAs doped with nitrogen impurities is investigated. Our theoretical model is based on the phenomenological Band Anticrossing Model (BAC) which we extended in order to include magnetic field and ... More

Chebyshev-BdG: an efficient numerical approach to inhomogeneous superconductivityJul 09 2010We propose a highly efficient numerical method to describe inhomogeneous superconductivity by using the kernel polynomial method in order to calculate the Green's functions of a superconductor. Broken translational invariance of any type (impurities, ... More

Current distribution in a two dimensional electron gas exposed to a perpendicular nonhomogeneous magnetic field of a chess configurationJul 30 2003We have studied a finite two-dimensional electron system exposed to a normal nonhomogeneous magnetic field of a chess configuration. Using the conformal mapping method we obtain an exact analytical solution for the electric field distribution in terms ... More

Electron capture in GaAs quantum wells via electron-electron and optic phonon scatteringNov 13 1995Nov 15 1995Electron capture times in a separate confinement quantum well (QW) structure with finite electron density are calculated for electron-electron (e-e) and electron-polar optic phonon (e-pop) scattering. We find that the capture time oscillates as function ... More

Kronig-Penney model on bilayer graphene: spectrum and transmission periodic in the strength of the barriersJan 21 2011We show that the transmission through single and double {\delta}-function potential barriers of strength P in bilayer graphene is periodic in P with period {\pi}. For a certain range of P values we find states that are bound to the potential barrier and ... More

Dirac electrons in a Kronig-Penney potential: dispersion relation and transmission periodic in the strength of the barriersNov 20 2009The transmission T and conductance G through one or multiple one-dimensional, delta-function barriers of two-dimensional fermions with a linear energy spectrum are studied. T and G are periodic functions of the strength P of the delta-function barrier ... More

Field-enhanced critical parameters in magnetically nanostructured superconductorsApr 25 2005Within the phenomenological Ginzburg-Landau theory, we demonstrate the enhancement of superconductivity in a superconducting film, when nanostructured by a lattice of magnetic particles. Arrays of out-of-plane magnetized dots (MDs) extend the critical ... More

Strain engineered graphene using a nanostructured substrate: II Pseudo-magnetic fieldsApr 28 2012The strain induced pseudo-magnetic field in supported graphene deposited on top of a nanostructured substrate is investigated by using atomistic simulations. Step, elongated trench, one dimensional barrier, spherical bubbles, Gaussian bump and Gaussian ... More

Effect of grain boundary on the buckling of graphene nanoribbonsMar 03 2012The buckling of graphene nano-ribbons containing a grain boundary is studied using atomistic simulations where free and supported boundary conditions are invoked. We found that when graphene contains a small angle grain boundary the buckling strains are ... More

Graphene on boron-nitride: Moiré pattern in the van der Waals energyApr 19 2014The spatial dependence of the van der Waals (vdW) energy between graphene and hexagonal boron-nitride (h-BN) is investigated using atomistic simulations. The van der Waals energy between graphene and h-BN shows a hexagonal superlattice structure identical ... More

Non-homogeneous magnetic field induced magnetic edge states and their transport in a quantum wireNov 27 2000The spectrum of magnetic edge states and their transport properties in the presence of a perpendicular non-homogeneous magnetic field in a quantum wire formed by a parabolic confining potential are obtained. Systems are studied where the magnetic field ... More

Electron-phonon bound state in grapheneJan 13 2012The fine structure of the Dirac energy spectrum in graphene induced by electron-optical phonon coupling is investigated in the portion of the spectrum near the phonon emission threshold. The derived new dispersion equation in the immediate neighborhood ... More

Vortex-antivortex nucleation in magnetically nanotextured superconductors: Magnetic-field-driven and thermal scenariosApr 25 2005Within the Ginzburg-Landau formalism, we predict two novel mechanisms of vortex-antivortex nucleation in a magnetically nanostructured superconductor. Although counterintuitive, nucleation of vortex-antivortex pairs can be activated in a superconducting ... More

Strain engineered graphene using a nanostructured substrate: I DeformationsApr 28 2012Using atomistic simulations we investigate the morphological properties of graphene deposited on top of a nanostructured substrate. Sinusoidally corrugated surfaces, steps, elongated trenches, one dimensional and cubic barriers, spherical bubbles, Gaussian ... More

Nanoindentation of a circular sheet of bilayer grapheneMay 12 2011Nanoindentation of bilayer graphene is studied using molecular dynamics simulations. We compared our simulation results with those from elasticity theory as based on the nonlinear F\"{o}ppl-Hencky equations with rigid boundary condition. The force deflection ... More

Quantum transport in graphene Hall bars: Effects of vacancy disorderNov 24 2016Using the tight-binding model, we investigate the influence of vacancy disorder on electrical transport in graphene Hall bars in the presence of quantizing magnetic fields. Disorder, induced by a random distribution of monovacancies, breaks the graphene ... More

Spectrum of exciton states in monolayer transition metal dichalcogenides: angular momentum and Landau levelsMar 28 2019A four-band exciton Hamiltonian is constructed starting from the single-particle Dirac Hamiltonian for charge carriers in monolayer transition metal dichalcogenides (TMDs). The angular part of the exciton wave function can be separated from the radial ... More

Magneto-optical transport properties of monolayer phosphoreneMay 26 2015Jul 22 2015The electronic properties of monolayer phosphorene are exotic due to its puckered structure and large intrinsic direct band gap. We derive and discuss its band structure in the presence of a perpendicular magnetic field. Further, we evaluate the magneto-optical ... More

Vortex manipulation in a superconducting matrix with view on applicationsMay 11 2010We show how a single flux quantum can be effectively manipulated in a superconducting film with a matrix of blind holes. Such a sample can serve as a basic memory element, where the position of the vortex in a [k x l] matrix of pinning sites defines the ... More

Vortex-Antivortex Lattices in Superconducting Films with Magnetic Pinning ArraysApr 25 2005Novel vortex structures are found when a thin superconducting film (SC) is covered with a lattice of out-of-plane magnetized magnetic dots (MDs). The stray magnetic field of the dots confines the vortices to the MD regions, surrounded by antivortices ... More

The response function of a Hall magnetosensorDec 17 2001Patterned two-dimensional electron gas (2DEG) systems into micrometer Hall bars can be used as Hall magnetosensors to provide detailed information on the magnetic field distribution. In this way, ballistic Hall probes have already been studied and used ... More

Graphene: a perfect nanoballoonOct 22 2008We have performed a first-principles density functional theory investigation of the penetration of helium atoms through a graphene monolayer with defects. The relaxation of the graphene layer caused by the incoming helium atoms does not have a strong ... More

Vortex structure in mesoscopic superconductorsDec 17 2001The nonlinear Ginzburg-Landau equations are solved numerically in order to investigate the vortex structure in thin superconducting disks of arbitrary shape. Depending on the size of the system and the strength of the applied magnetic field giant vortex, ... More

Monte-Carlo simulation of the coherent backscattering of electrons in a ballistic systemFeb 03 1999We study weak localization effects in the ballistic regime as induced by man-made scatterers. Specular reflection of the electrons off these scatterers results into backscattered trajectories which interfere with their time-reversed path resulting in ... More

Optically Detected Magnetophonon Resonances in Polar SemiconductorsAug 26 1999Magnetophonon resonances are found for $\omega_{c}=\omega_{LO}/N$ with N=1,2,3 .... in the polaron cyclotron resonance (CR) linewidth and effective mass of bulk polar semiconductors. The CR mass and the linewidth are obtained from the full polaron magneto-optical ... More

Stability of spintronic devices based on quantum ring networksJun 30 2009Transport properties in mesoscopic networks are investigated, where the strength of the (Rashba-type) spin-orbit coupling is assumed to be tuned with external gate voltages. We analyze in detail to what extent the ideal behavior and functionality of some ... More

Magnetic field dependence of the many-electron states in a magnetic quantum dot: The ferromagnetic-antiferromagnetic transitionNov 18 2008The electron-electron correlations in a many-electron (Ne = 1, 2,..., 5) quantum dot confined by a parabolic potential is investigated in the presence of a single magnetic ion and a perpendicular magnetic field. We obtained the energy spectrum and calculated ... More

Paramagnetic adsorbates on graphene: a charge transfer analysisJun 03 2008We introduce a modified version of the Hirshfeld charge analysis method and demonstrate its accurateness by calculating the charge transfer between the paramagnetic molecule NO2 and graphene. The charge transfer between paramagnetic molecules and a graphene ... More

Temporary cooling of quasiparticles and delay in voltage response of superconducting bridges after abrupt switching on the supercritical currentJul 11 2014Aug 15 2014We revisit the problem of the dynamic response of a superconducting bridge after abruptly switching on the supercritical current $I>I_c$. In contrast to previous theoretical works we take into account spatial gradients and use both the local temperature ... More

Dynamic transitions between metastable states in a superconducting ringJul 23 2002Applying the time-dependent Ginzburg-Landau equations, transitions between metastable states of a superconducting ring are investigated in the presence of an external magnetic field. It is shown that if the ring exhibits several metastable states at a ... More

The two electron artificial moleculeJul 12 1998Exact results for the classical and quantum system of two vertically coupled two-dimensional single electron quantum dots are obtained as a function of the interatomic distance (d) and with perpendicular magnetic field. The classical system exhibits a ... More

Four band tunneling in bilayer grapheneMar 27 2013The conductance, the transmission and the reflection probabilities through rectangular potential barriers and pn-junctions are obtained for bilayer graphene taking into account the four bands of the energy spectrum. We have evaluated the importance of ... More

Interplay between tunneling and exchange effects in the two electron double quantum dot moleculeFeb 17 1999May 24 1999The electronic structure of two vertically coupled quantum dots containing two electrons is investigated in the presence of interdot tunneling. Our approach also includes the interdot exchange and we find that the tunneling is affected by the Coulomb ... More

Spectral properties of charged particles in a classical finite two-dimensional systemSep 14 1994We present a study of the spectral properties like the energy spectrum, the eigenmodes and density of states of a classical finite system of two-dimensional (2D) charged particles which are confined by a quadratic potential. Using the method of Newton ... More

Hall potentiometer in the ballistic regimeJan 14 1999We demonstrate theoretically how a two-dimensional electron gas can be used to probe local potential profiles using the Hall effect. For small magnetic fields, the Hall resistance is inversely proportional to the average potential profile in the Hall ... More

Dependence of the vortex configuration on the geometry of mesoscopic flat samplesJun 28 2001The influence of the geometry of a thin superconducting sample on the penetration of the magnetic field lines and the arrangement of vortices are investigated theoretically. We compare superconducting disks, squares and triangles with the same surface ... More

Ground state of excitons and charged excitons in a quantum wellMar 01 2000A variational calculation of the ground state of a neutral exciton and of positively and negatively charged excitons (trions) in single quantum well is presented. We study the dependance of the correlation energy and of the binding energy on the well ... More

Binding energy of localized biexcitons in quantum wellsMay 14 1998A variational calculation of the ground state energy of a biexciton in a GaAs/AlGaAs quantum well is presented. The well width fluctuations leading to trapping of the biexcitons are modeled by a parabolic potential. The results obtained for different ... More

Magnetic-field-induced binding of few-electron systems in shallow quantum dotsJun 20 2006Binding of few-electron systems in two-dimensional potential cavities in the presence of an external magnetic field is studied with the exact diagonalization approach. We demonstrate that for shallow cavities the few-electron system becomes bound only ... More

Electron scattering on circular symmetric magnetic profiles in a two-dimensional electron gasJun 19 2001The quasi-bound and scattered states in a 2DEG subjected to a circular symmetric steplike magnetic profile with zero average magnetic field are studied. We calculate the effect of a random distribution of such identical profiles on the transport properties ... More

Condensate entanglement and multigap superconductivity in nanoscale superconductorsJun 24 2010A Green functions approach is used to study superconductivity in nanofilms and nanowires. We show that the superconducting condensate results from the multimodal entanglement, or internal Josephson coupling, of the subcondensates associated with the manifold ... More

Paramagnetic Meissner effect in mesoscopic samplesJan 10 2000Using the non-linear Ginzburg-Landau (GL) theory, we study the magnetic response of different shaped samples in the field-cooled regime (FC). For high external magnetic fluxes, the conventional diamagnetic response under cooling down can be followed by ... More

Transitions between different superconducting states in mesoscopic disksOct 07 1999Using a linear analysis, we study the stability of giant-vortex states in very thin disks. The vortex expulsion and penetration fields are obtained for finite thickness disks from a numerical solution of the non-linear Ginzburg-Landau (GL) equations. ... More

Positively charged magneto-excitons in a semiconductor quantum wellMay 09 2001A variational calculation of the lower singlet and triplet states of positively charged excitons (trions) confined to a single quantum well and in the presence of a perpendicular magnetic field is presented. We study the dependence of the energy levels ... More

Optical Properties of GaS-Ca(OH)$_2$ bilayer heterostructureJan 24 2016Finding novel atomically-thin heterostructures and understanding their characteristic properties are critical for developing better nanoscale optoelectronic devices. In this study, we investigate the electronic and optical properties of GaS-Ca(OH)$_2$ ... More

D'yakonov-Perel' spin relaxation in InSb/AlInSb quantum wellsNov 04 2009We investigate theoretically the D'yakonov-Perel' spin relaxation time by solving the eight-band Kane model and Poisson equation self-consistently. Our results show distinct behavior with the single-band model due to the anomalous spin-orbit interactions ... More

Topological Defects and Non-homogeneous Melting of Large 2D Coulomb ClustersJul 30 2002The configurational and melting properties of large two-dimensional clusters of charged classical particles interacting with each other via the Coulomb potential are investigated through the Monte Carlo simulation technique. The particles are confined ... More

Magnetic field dependence of the energy of negatively charged excitons in semiconductor quantum wellsOct 30 2000A variational calculation of the spin-singlet and spin-triplet state of a negatively charged exciton (trion) confined to a single quantum well and in the presence of a perpendicular magnetic field is presented. We calculated the probability density and ... More

Stark effect on the exciton spectra of vertically coupled quantum dots: horizontal field orientation and non-aligned dotsDec 11 2006We study the effect of an electric-field on an electron-hole pair in an asymmetric system of vertically coupled self-assembled quantum dots taking into account their non-perfect alignment. We show that the non-perfect alignment does not qualitatively ... More

Electron spin and charge switching in a coupled quantum dot quantum ring systemJun 22 2004Few-electron systems confined in a quantum dot laterally coupled to a surrounding quantum ring in the presence of an external magnetic field are studied by exact diagonalization. The distribution of electrons between the dot and the ring is influenced ... More

Giant vortices in small mesoscopic disks: an approximate descriptionNov 19 2001We present an approximate description of the giant vortex state in a thin mesoscopic superconducting disk within the phenomenological Ginzburg-Landau approach. Analytical asymptotic expressions for the energies of the states with fixed vorticity are obtained ... More

Magnetoplasma excitations of two vertically coupled dotsDec 05 1997A classical hydrodynamic approach is used to calculate the magnetoplasma excitations of two vertically coupled electron dots. The electrons are confined by different parabolic potentials in which case Kohn's theorem is no longer valid. The equilibrium ... More

Ginzburg-Landau theory of the zig-zag transition in quasi-one-dimensional classical Wigner crystalsJul 18 2012We present a mean-field description of the zig-zag phase transition of a quasi-one-dimensional system of strongly interacting particles, with interaction potential $r^{-n}e^{-r/\lambda}$, that are confined by a power-law potential ($y^{\alpha}$). The ... More

Enhancement of the retrapping current of superconducting microbridges of finite lengthOct 06 2011We theoretically find that the resistance of a superconducting microbridge/nanowire {\it decreases} while the retrapping current $I_r$ for the transition to the superconducting state {\it increases} when one suppresses the magnitude of the order parameter ... More

Adsorption of H2O, NH3, CO, NO2, and NO on graphene: A first-principles studyOct 09 2007Motivated by the recent realization of graphene sensors to detect individual gas molecules, we investigate the adsorption of H2O, NH3, CO, NO2, and NO on a graphene substrate using first-principles calculations. The optimal adsorption position and orientation ... More

Dynamics of Vortex Shells in Mesoscopic Superconducting Corbino DisksOct 30 2006In mesoscopic superconducting disks vortices form shell structures as recently observed in Nb disks. We study the dynamics of such vortices, driven by an external current I_0, in a Corbino setup. At very low I_0, the system exhibits rigid body rotation ... More

Currents in a many-particle parabolic quantum dot under a strong magnetic fieldAug 31 2004Currents in a few-electron parabolic quantum dot placed into a perpendicular magnetic field are considered. We show that traditional ways of investigating the Wigner crystallization by studying the charge density correlation function can be supplemented ... More

Spin-dependent transmission through a chain of rings: influence of a periodically modulated spin-orbit interaction strength or ring radiusJul 20 2004We study ballistic electron transport through a finite chain of quantum circular rings in the presence of spin-orbit interaction of strength \alpha. For a single ring the transmission and reflection coefficients are obtained analytically and from them ... More

Stable and metastable states in a superconducting "eight" loop in applied magnetic fieldJan 30 2002The stable and metastable states of different configurations of a loop in the form of an eight is studied in the presence of a magnetic field. We find that for certain configurations the current is equal to zero for any value of the magnetic field leading ... More

Thermodynamic properties of the electron gas in multilayer graphene in the presence of a perpendicular magnetic fieldJan 06 2014The thermodynamic properties of the electron gas in multilayer graphene depend strongly on the number of layers and the type of stacking. Here we analyse how those properties change when we vary the number of layers for rhombohedral stacked multilayer ... More

Quantum states in a magnetic anti-dotJul 10 1998Jul 15 1998We study a new system in which electrons in two dimensions are confined by a non homogeneous magnetic field. The system consists of a heterostructure with on top of it a superconducting disk. We show that in this system electrons can be confined into ... More

Hamiltonian of a many-electron system with single-electron and electron-pair states in a two-dimensional periodic potentialJan 20 2015Based on the metastable electron-pair energy band in a two-dimensional (2D) periodic potential obtained previously by Hai and Castelano [J. Phys.: Condens. Matter 26, 115502 (2014)], we present in this work a Hamiltonian of many electrons consisting of ... More

Many-body effects in the cyclotron resonance of a magnetic dotSep 24 2009Intraband cyclotron resonance (CR) transitions of a two-electron quantum dot containing a single magnetic ion is investigated for different Coulomb interaction strengths and different positions of the magnetic ion. In contrast to the usual parabolic quantum ... More

Spin-dependent (magneto)transport through a ring due to spin-orbit interactionJul 20 2004Electron transport through a one-dimensional ring connected with two external leads, in the presence of spin-orbit interaction (SOI) of strength \alpha and a perpendicular magnetic field is studied. Applying Griffith's boundary conditions we derive analytic ... More

Flux penetration and expulsion in thin superconducting disksAug 18 1999Using an expansion of the order parameter over the eigenfunctions of the linearized first Ginzburg-Landau (GL) equation, we obtain numerically the saddle points of the free energy separating the stable states with different number of vortices. In contrast ... More

Influence of the confinement geometry on surface superconductivityMay 03 1999The nucleation field for surface superconductivity, $H_{c3}$, depends on the geometrical shape of the mesoscopic superconducting sample and is substantially enhanced with decreasing sample size. As an example we studied circular, square, triangular and ... More

Heating of quasiparticles driven by oscillations of the order parameter in short superconducting microbridgesMay 27 2011We predict 'heating' of quasiparticles driven by order parameter oscillations in the resistive state of short superconducting microbridges. The finite relaxation time of the magnitude of the order parameter $|\Delta|$ and the dependence of the spectral ... More

Rearrangement of the vortex lattice due to instabilities of vortex flowJun 08 2007With increasing applied current we show that the moving vortex lattice changes its structure from a triangular one to a set of parallel vortex rows in a pinning free superconductor. This effect originates from the change of the shape of the vortex core ... More