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Multicomponent screening and superfluidity in gapped electron-hole double bilayer graphene with realistic bandsDec 10 2018Superfluidity has recently been reported in double electron-hole bilayer graphene. The multiband nature of the bilayers is important because of the very small band gaps between conduction and valence bands. The long range nature of the superfluid pairing ... More

Phonon hydrodynamics, thermal conductivity and second sound in 2D crystalsApr 12 2019Starting from our previous work where we have obtained a system of coupled integro-differential equations for acoustic sound waves and phonon density fluctuations in 2D crystals, we derive here the corresponding hydrodynamic equations and study their ... More

Magnetoelectronic properties of normal and skewed phosphorene nanoribbonsApr 10 2017The energy spectrum and eigenstates of single-layer black phosphorous nanoribbons in the presence of perpendicular magnetic field and in-plane transverse electric field are investigated by means of a tight-binding method and the effect of different types ... More

Helical edge states in silicene and germanene nanorings in perpendicular magnetic fieldJul 28 2017Sep 01 2017Due to nonzero intrinsic spin-orbit interaction in buckled honeycomb crystal structures, silicene and germanene exhibit interesting topological properties, and are therefore candidates for the realization of the quantum spin Hall effect. We employ the ... More

Electronic, Optical and Mechanical Properties of Silicene DerivativesAug 10 2016Successful isolation of graphene from graphite opened a new era for material science and con- densed matter physics. Due to this remarkable achievement, there has been an immense interest to synthesize new two dimensional materials and to investigate ... More

Self-Organized Platinum Nanoparticles on Freestanding GrapheneDec 11 2014Dec 18 2014Freestanding graphene membranes were successfully functionalized with platinum nanoparticles (Pt NPs). High-resolution transmission electron microscopy revealed a homogeneous distribution of single-crystal Pt NPs that tend to exhibit a preferred orientation. ... More

Realization of a Tunable Artificial Atom at a Supercritically Charged Vacancy in GrapheneAug 31 2015Apr 14 2016The remarkable electronic properties of graphene have fueled the vision of a graphene-based platform for lighter, faster and smarter electronics and computing applications. One of the challenges is to devise ways to tailor its electronic properties and ... More

Tuning a Circular p-n Junction in Graphene from Quantum Confinement to Optical GuidingMay 20 2017The motion of massless Dirac-electrons in graphene mimics the propagation of photons. This makes it possible to control the charge-carriers with components based on geometrical-optics and has led to proposals for an all-graphene electron-optics platform. ... More

Flat Bands in Buckled Graphene SuperlatticesApr 23 2019Interactions between stacked two-dimensional (2D) atomic crystals can radically change their properties, leading to essentially new materials in terms of the electronic structure. Here we show that monolayers placed on an atomically flat substrate can ... 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

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

New Nanoporous Graphyne Monolayer as Nodal Line Semimetal: Double Dirac Points with an Ultrahigh Fermi VelocityMar 18 2018Two-dimensional (2D) carbon materials play an important role in nanomaterials. We propose a new carbon monolayer, named hexagonal-4,4,4-graphyne (H4,4,4-graphyne), which is a nanoporous structure composed of rectangular carbon rings and triple bonds of ... More

Antiferromagnetism in hexagonal graphene structures: Rings vs dotsFeb 19 2013The mean-field Hubbard model is used to investigate the formation of the antiferromagnetic phase in hexagonal graphene rings with inner zigzag edges. The outer edge of the ring was taken to be either zigzag or armchair, and we found that both types of ... 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

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

Cyclotron resonance of a magnetic quantum dotNov 18 2008The energy spectrum of a one-electron quantum dot doped with a single magnetic ion is studied in the presence of an external magnetic field. The allowed cyclotron resonance (CR) transitions are obtained together with their oscillator strength (OS) as ... More

Transition Between Ground State and Metastable States in Classical 2D AtomsJun 20 2001Structural and static properties of a classical two-dimensional (2D) system consisting of a finite number of charged particles which are laterally confined by a parabolic potential are investigated by Monte Carlo (MC) simulations and the Newton optimization ... More

Pade approximants for the ground-state energy of closed-shell quantum dotsJul 24 1997Analytic approximations to the ground-state energy of closed-shell quantum dots (number of electrons from 2 to 210) are presented in the form of two-point Pade approximants. These Pade approximants are constructed from the small- and large-density limits ... More

Vibrational properties of nanographeneJan 28 2013The eigenmodes and the vibrational density of states of the ground state configuration of graphene clusters are calculated using atomistic simulations. The modified Brenner potential is used to describe the carbon-carbon interaction and carbon-hydrogen ... More

Tunable circular dipolelike system in graphene: Mixed electron-hole statesApr 04 2019Coupled electron-hole states are realized in a system consisting of a combination of an electrostatic potential barrier and ring-shaped potential well, which resembles a circular dipole. A perpendicular magnetic field induces confined states inside the ... More

Adsorption of Alkali, Alkaline Earth and Transition Metal Atoms on SiliceneFeb 06 2013The adsorption characteristics of alkali, alkaline earth and transition metal adatoms on silicene, a graphene-like monolayer structure of silicon, are analyzed by means of first-principles calculations. In contrast to graphene, interaction between the ... More

Strongly interacting $σ$-electrons and MgB$_2$ superconductivitySep 19 2001MgB$(p^{n_{\sigma}}p^{n_{\pi}})_{2}$ is classified as a system with strongly interacting $\sigma$-electrons and non-correlated $\pi$-electrons of boron ions. The kinematic and Coulomb interaction V between the orbitally degenerated $\sigma$-electrons ... More

Superconducting films with antidot arrays - novel behavior of the critical currentMar 06 2006Novel behavior of the critical current density $j_{c}$ of a regularly perforated superconducting film is found, as a function of applied magnetic field $H$. Previously pronounced peaks of $j_{c}$ at matching fields were always found to decrease with increasing ... More

Electronic properties of graphene nano-flakes: Energy gap, permanent dipole, termination effect and Raman spectroscopyFeb 05 2014The electronic properties of graphene nano-flakes (GNFs) with different edge passivation is investigated by using density functional theory. Passivation with F and H atoms are considered: C$_{N_c}$ X$_{N_x}$ (X=F or H). We studied GNFs with $10<N_c<56$ ... More

Geodesics on Margulis spacetimesFeb 02 2011Aug 15 2011Let M be a Margulis spacetime whose associated complete hyperbolic surface S has compact convex core. Generalizing the correspondence between closed geodesics on M and closed geodesics on S, we establish an orbit equivalence between recurrent spacelike ... More

Orbital magnetic moments in insulating Dirac systems: Impact on magnetotransport in graphene van der Waals heterostructuresAug 06 2014Nov 14 2014In honeycomb Dirac systems with broken inversion symmetry, orbital magnetic moments coupled to the valley degree of freedom arise due to the topology of the band structure, leading to valley-selective optical dichroism. On the other hand, in Dirac systems ... More

Melting of graphene clustersApr 22 2013Density-functional tight-binding and classical molecular dynamics simulations are used to investigate the structural deformations and melting of planar carbon nano-clusters $C_{N}$ with N=2-55. The minimum energy configurations for different clusters ... More

Electric field induced structural changes of water confined between two graphene layersJan 22 2016An external electric field changes the physical properties of polar-liquids due to the reorientation of their permanent dipoles. For example it should affect significantly the physical properties of water confined in a nanochannel. The latter effect is ... More

Spin-valley filtering in strained graphene structures with artificially induced carrier mass and spin-orbit couplingJun 20 2014Jul 24 2014The interplay of massive electrons with spin-orbit coupling in bulk graphene results in a spin-valley dependent gap. Thus, a barrier with such properties can act as a filter, transmitting only opposite spins from opposite valleys. In this Letter we show ... More

Chiral properties of topological-state loopsFeb 26 2015Jun 05 2015The angular momentum quantization of chiral gapless modes confined to a circularly shaped interface between two different topological phases is investigated. By examining several different setups, we show analytically that the angular momentum of the ... More

Enhancement of electron-hole superfluidity in double few-layer grapheneJun 10 2014Dec 09 2014We propose two coupled electron-hole sheets of few-layer graphene as a new nanostructure to observe superfluidity at enhanced densities and enhanced transition temperatures. For ABC stacked few-layer graphene we show that the strongly correlated electron-hole ... More

Wigner crystallization in transition metal dichalcogenides: A new approach to correlation energyNov 11 2016We introduce a new approach for the correlation energy of one- and two-valley two-dimensional electron gas (2DEG) systems. Our approach is based on a random phase approximation at high densities and a classical approach at low densities, with interpolation ... More

Ginzburg-Landau theory and effects of pressure on a two-band superconductor : application to MgB2Jan 24 2003We present a model of pressure effects of a two-band superconductor based on a Ginzburg-Landau free energy with two order parameters. The parameters of the theory are pressure as well as temperature dependent. New pressure effects emerge as a result of ... More

Tuning the electronic properties of gated multilayer phosphorene: A self-consistent tight-binding studyApr 13 2018By taking account of the electric-field-induced charge screening, a self-consistent calculation within the framework of the tight-binding approach is employed to obtain the electronic band structure of gated multilayer phosphorene and the charge densities ... More

High temperature conductance of a two-dimensional superlattice controlled by spin-orbit interactionMar 03 2015Rashba-type spin-orbit interaction (SOI) controlled band structure of a two-dimensional superlattice allows for the modulation of the conductance of finite size devices by changing the strength of the SOI. We consider rectangular arrays and find that ... More

Tuning of energy levels and optical properties of graphene quantum dotsMay 05 2008We investigate theoretically the magnetic levels and optical properties of zigzag- and armchair-edged hexagonal graphene quantum dots (GQDs) utilizing the tight-binding method. A new bound edge state at zero energy appears for the zigzag GQDs in the absence ... More

MgB2: superconductivity and pressure effectsApr 03 2002Jan 24 2003We present a Ginzburg-Landau theory for a two-band superconductor with emphasis on MgB$_{2}$. Experiments are proposed which lead to identification of the possible scenarios: whether both $\sigma $- and $\pi $-bands superconduct or $\sigma $% -alone. ... More

Electric- and magnetic-field dependence of the electronic and optical properties of phosphorene quantum dotsDec 23 2016Recently, black phosphorus quantum dots were fabricated experimentally. Motivated by these experiments, we theoretically investigate the electronic and optical properties of rectangular phosphorene quantum dots (RPQDs) in the presence of an in-plane electric ... More

Electronic properties of bilayer phosphorene quantum dots in the presence of perpendicular electric and magnetic fieldsSep 16 2017Using the tight-binding approach, we investigate the electronic properties of bilayer phosphorene (BLP) quantum dots (QDs) in the presence of perpendicular electric and magnetic fields. Since BLP consists of two coupled phosphorene layers, it is of interest ... More

Electric-field modulation of linear dichroism and Faraday rotation in few-layer phosphoreneNov 29 2018Electro-optical modulators, which use an electric voltage (or an electric field) to modulate a beam of light, are essential elements in present-day telecommunication devices. Using a self-consistent tight-binding approach combined with the standard Kubo ... More

Probing the Ionization States of Polycyclic Aromatic Hydrocarbons via the 15-20 μm Emission BandsAug 19 2015We report new correlations between ratios of band intensities of the 15-20 {\mu}m emission bands of polycyclic aromatic hydrocarbons (PAHs) in a sample of fifty-seven sources observed with Spitzer/IRS. This sample includes Large Magellanic Cloud point ... More

Strain-induced band gaps in bilayer grapheneNov 21 2011We present a tight-binding investigation of strained bilayer graphene within linear elasticity theory, focusing on the different environments experienced by the A and B carbon atoms of the different sublattices. We find that the inequivalence of the A ... More

Off center $D^-$ centers in a quantum well in the presence of a perpendicular magnetic field: angular momentum transition and magnetic evaporationMay 13 1998We investigate the effect of the position of the donor in the quantum well on the energy spectrum and the oscillator strength of the D- system in the presence of a perpendicular magnetic field. As a function of the magnetic field we find that when the ... More

Superconducting nanofilms: molecule-like pairing induced by quantum confinementJul 27 2011Quantum confinement of the perpendicular motion of electrons in single-crystalline metallic superconducting nanofilms splits the conduction band into a series of single-electron subbands. A distinctive feature of such a nanoscale multi-band superconductor ... More

Magnetic interface states in graphene-based quantum wiresOct 09 2006The electronic states of a finite-width graphene sheet in the presence of an electrostatic confining potential and a perpendicular magnetic field are investigated. The confining potential shifts the Landau levels inside the well and creates current-carrying ... More

The split-operator technique for the study of spinorial wavepacket dynamicsJan 04 2016The split-operator technique for wave packet propagation in quantum systems is expanded here to the case of propagating wave functions describing Schr\"odinger particles, namely, charge carriers in semiconductor nanostructures within the effective mass ... More

Oscillating magnetoresistance in diluted magnetic semiconductor barrier structuresJul 10 2001Jul 13 2001Ballistic spin polarized transport through diluted magnetic semiconductor (DMS) single and double barrier structures is investigated theoretically using a two-component model. The tunneling magnetoresistance (TMR) of the system exhibits oscillating behavior ... More

Structure and energetics of hydrogen chemisorbed on a single graphene layer to produce graphaneMar 14 2011Chemisorption of hydrogen on graphene is studied using atomistic simulations with the second generation of reactive empirical bond order Brenner inter-atomic potential. The lowest energy adsorption sites and the most important metastable sites are determined. ... More

Remarkable effect of stacking on the electronic and optical properties of few layer black phosphorusJun 15 2015The effect of the number of stacking layers and the type of stacking on the electronic and optical properties of bilayer and trilayer black phosphorus are investigated by using first principles calcula- tions within the framework of density functional ... More

Two-component mixture of charged particles confined in a channel: meltingJun 09 2010The melting of a binary system of charged particles confined in a {\it quasi}-one-dimensional parabolic channel is studied through Monte Carlo simulations. At zero temperature the particles are ordered in parallel chains. The melting is anisotropic and ... More

Canonical lossless state-space systems: Staircase forms and the Schur algorithmDec 15 2010A new finite atlas of overlapping balanced canonical forms for multivariate discrete-time lossless systems is presented. The canonical forms have the property that the controllability matrix is positive upper triangular up to a suitable permutation of ... More

Balanced realizations of discrete-time stable all-pass systems and the tangential Schur algorithmDec 15 2010In this paper, the connections are investigated between two different approaches towards the parametrization of multivariable stable all-pass systems in discrete-time. The first approach involves the tangential Schur algorithm, which employs linear fractional ... More

Spin-orbit interaction controlled properties of two-dimensional superlattices: Spintronic crystalsMar 03 2015The band structure of two-dimensional artificial superlattices in the presence of (Rashba-type) spin-orbit interaction (SOI) is presented. The position and shape of the energy bands in these spintronic crystals depend on the geometry as well as the strength ... More

Confinement effects on intermediate state flux patterns in mesoscopic type-I superconductorsOct 28 2009Intermediate state (IS) flux structures in mesoscopic type-I superconductors are investigated within the Ginzburg-Landau theory. In addition to well-established tubular and laminar structures, the strong confinement leads to the formation of (i) a phase ... More

Ground-state energy of confined charged bosons in two dimensionsJun 22 1998The Pade approximant technique and the variational Monte Carlo method are applied to determine the ground-state energy of a finite number of charged bosons in two dimensions confined by a parabolic trap. The particles interact repulsively through a Coulombic, ... More

Stable Half-Metallic Monolayers of FeCl$_2$Jul 30 2015The structural, electronic and magnetic properties of single layers of Iron Dichloride (FeCl$_{2}$) were calculated using first principles calculations. We found that the 1T phase of the single layer FeCl$_{2}$ is 0.17 eV/unit cell more favorable than ... More

GraphAne: From Synthesis to ApplicationsFeb 20 2015Atomically thin crystals have recently been the focus of attention in particular after the synthesis of graphene, a monolayer hexagonal crystal structure of carbon. In this novel material class the chemically derived graphenes have attracted tremendous ... More

Characterization of the size and position of electron-hole puddles at a graphene p-n junctionMar 24 2016The effect of an electron-hole puddle on the electrical transport when governed by snake states in a bipolar graphene structure is investigated. Using numerical simulations we show that information on the size and position of the electron-hole puddle ... More

Exciton states in a circular graphene quantum dot: magnetic field induced intravalley to intervalley transitionDec 23 2016The magnetic-field dependence of the energy spectrum, wave function, binding energy and oscillator strength of exciton states confined in a circular graphene quantum dot (CGQD) are obtained within the configuration interaction (CI) method. We predict ... More

Two-band superconductors: Extended Ginzburg-Landau formalism by a systematic expansion in small deviation from the critical temperatureJul 26 2012We derive the extended Ginzburg-Landau (GL) formalism for a clean s-wave two-band superconductor by employing a systematic expansion of the free-energy functional and the corresponding matrix gap equation in powers of the small deviation from the critical ... More

Piezoelectric surface acoustical phonon limited mobility of electrons in graphene on a GaAs substrateNov 27 2012We study the mobility of Dirac fermions in monolayer graphene on a GaAs substrate, restricted by the combined action of the extrinsic potential of piezoelectric surface acoustical phonons of GaAs (PA) and of the intrinsic deformation potential of acoustical ... More

Melting of Partially Fluorinated Graphene: From Detachment of Fluorine Atoms to Large Defects and Random CoilsDec 26 2013The melting of fluorographene is very unusual and depends strongly on the degree of fluorination. For temperatures below 1000 K, fully fluorinated graphene (FFG) is thermo-mechanically more stable than graphene but at T$_m\approx$2800 K FFG transits to ... More

Multi-component plasmons in monolayer MoS$_2$ with circularly polarized optical pumpingAug 16 2017By making use of circularly polarized light and electrostatic gating, monolayer molybdenum disulfide (ML-MoS$_2$) can form a platform supporting multiple types of charge carriers. They can be discriminated by their spin, valley index or whether they're ... More

Giant paramagnetic Meissner effect in multiband superconductorsAug 07 2015Superconductors, ideally diamagnetic when in the Meissner state, can also exhibit paramagnetic behavior due to trapped magnetic flux. In the absence of pinning such paramagnetic response is weak, and ceases with increasing sample thickness. Here we show ... More

Distinct magnetic signatures of fractional vortex configurations in multiband superconductorsFeb 28 2015Jul 21 2015Vortices carrying fractions of a flux quantum are predicted to exist in multiband superconductors, where vortex core can split between multiple band-specific components of the superconducting condensate. Using the two-component Ginzburg-Landau model, ... More

Conductance Quantization in a Periodically Modulated Quantum Channel: backscattering and mode mixingSep 25 1997It is known that the conductance of a quantum point contact is quantized in units of $2e^2/h$ and this quantization is destroyed by a non-adiabatic scatterer in the point contact, due to backscattering. Recently, it was shown [Phys. Rev. Lett. 71, 137 ... More

Thermomechanical properties of a single hexagonal boron nitride sheetApr 22 2013Using atomistic simulations we investigate the thermodynamical properties of a single atomic layer of hexagonal boron nitride (h-BN). The thermal induced ripples, heat capacity, and thermal lattice expansion of large scale h-BN sheets are determined and ... More

Electron energy and temperature relaxation in graphene on a piezoelectric substrateDec 22 2013May 12 2014We study the energy and temperature relaxation of electrons in graphene on a piezoelectric substrate. Scattering from the combined potential of extrinsic piezoelectric surface acoustical (PA) phonons of the substrate and intrinsic deformation acoustical ... More

Tunable skewed edges in puckered structuresDec 07 2015Jun 15 2016We propose a new type of edges, arising due to the anisotropy inherent in the puckered structure of a honeycomb system such as in phosphorene. Skewed-zigzag and skewed-armchair nanoribbons are semiconducting and metallic, respectively, in contrast to ... More

Thermal rippling behavior of graphaneJul 07 2012Thermal fluctuations of single layer hydrogenated graphene (graphane) are investigated using large scale atomistic simulations. By analyzing the mean square value of the height fluctuations $<h^2>$ and the height-height correlation function $H(q)$ for ... More

Metallic nanograins: spatially nonuniform pairing induced by quantum confinementNov 19 2010It is well-known that the formation of discrete electron levels strongly influences the pairing in metallic nanograins. Here we focus on another effect of quantum confinement in superconducting grains that was not studied previously, i.e., spatially nonuniform ... More

Formation of multi-quanta vortices in superconductors: electronic, calorimetric and magnetic evidenceJun 30 2011Jul 01 2011The ground state with vorticity larger than one in mesoscopic superconductors in applied magnetic field may manifest as a `giant'-vortex, where all vortices coalesce into a single singularity of the order parameter. Such a multi-quanta vortex may split ... More

Rippling, buckling and melting of single- and multi-layer MoS$_2$Dec 05 2014Large-scale atomistic simulations using the reactive empirical bond order force field approach is implemented to investigate thermal and mechanical properties of single-layer (SL) and multi-layer (ML) molybdenum disulfide (MoS$_2$). The amplitude of the ... More

The electric field as a novel switch for uptake/release of hydrogen storage in nitrogen doped grapheneNov 24 2011Nitrogen-doped graphene was recently synthesized and was reported to be a catalyst for hydrogen dissociative adsorption under a perpendicular applied electric field (F). In this work, the diffusion of H atoms on N-doped graphene, in the presence and absence ... More

Vortex states in nanoscale superconducting squares: the influence of quantum confinementMar 28 2013Oct 02 2013Bogoliubov-de Gennes theory is used to investigate the effect of the size of a superconducting square on the vortex states in the quantum confinement regime. When the superconducting coherence length is comparable to the Fermi wavelength, the shape resonances ... More

Rectification by imprinted phase in a Josephson junctionSep 28 2011A Josephson phase shift can be induced in a Josephson junction by a strategically nearby pinned Abrikosov vortex (AV). For an asymmetric distribution of imprinted phase along the junction (controlled by the position of the AV) such a simple system is ... More

Dirac and Klein-Gordon particles in one-dimensional periodic potentialsJan 20 2011We evaluate the dispersion relation for massless fermions, described by the Dirac equation, and for zero-spin bosons, described by the Klein-Gordon equation, moving in two dimensions and in the presence of a one-dimensional periodic potential. For massless ... More

Simplified model for the energy levels of quantum rings in single layer and bilayer grapheneFeb 08 2010Within a minimal model, we present analytical expressions for the eigenstates and eigenvalues of carriers confined in quantum rings in monolayer and bilayer graphene. The calculations were performed in the context of the continuum model, by solving the ... More

Landau levels in asymmetric graphene trilayersJul 04 2011The electronic spectrum of three coupled graphene layers (graphene trilayers) is investigated in the presence of an external magnetic field. We obtain analytical expressions for the Landau level spectrum for both the ABA and ABC - type of stacking, which ... More

Superconducting proximity effect in graphene under inhomogeneous strainNov 19 2011The interplay between quantum Hall states and Cooper pairs is usually hindered by the suppression of the superconducting state due to the strong magnetic fields needed to observe the quantum Hall effect. From this point of view graphene is special since ... More

A tight-binding investigation of biaxial strain induced topological phase transition in GeCH$_3$Jul 13 2017We propose a tight-binding (TB) model, that includes spin-orbit coupling (SOC), to describe the electronic properties of methyl-substituted germanane (GeCH$_3$). This model gives an electronic spectrum in agreement with first principle results close to ... More

Collective vortex phases in periodic plus random pinning potentialJun 30 2008Feb 23 2009We study theoretically the simultaneous effect of a regular and a random pinning potentials on the vortex lattice structure at filling factor of 1. This structure is determined by a competition between the square symmetry of regular pinning array, by ... More

D- shallow donor near a semiconductor-metal and a semiconductor-dielectric interfaceMay 13 2010The ground state energy and the extend of the wavefunction of a negatively charged donor (D-) located near a semiconductor-metal or a semiconductor-dielectric interface is obtained. We apply the effective mass approximation and use a variational two-electron ... More

Magnetoconductance properties of rectangular arrays of spintronic quantum ringsJun 17 2008Electron transport through multi-terminal rectangular arrays of quantum rings is studied in the presence of Rashba-type spin-orbit interaction (SOI) and of a perpendicular magnetic field. Using the analytic expressions for the transmission and reflection ... More

Valley-dependent Brewster angles and Goos-Hanchen effect in strained grapheneAug 28 2010Sep 26 2011We demonstrate theoretically how local strains in graphene can be tailored to generate a valley polarized current. By suitable engineering of local strain profiles, we find that electrons in opposite valleys (K or K') show different Brewster-like angles ... More

Interplay between s-d exchange interaction and Rashba effect: spin-polarized transportSep 21 2006We investigate the spin-polarized transport properties of a two-dimensional electron gas in a n-type diluted magnetic narrow gap semiconductor quantum well subjected to a perpendicular magnetic and electric field. Interesting beating patterns in the magneto ... More

Kink-antikink vortex transfer in periodic-plus-random pinning potential: Theoretical analysis and numerical experimentsJul 24 2009The influence of random pinning on the vortex dynamics in a periodic square potential under an external drive is investigated. Using theoretical approach and numerical experiments, we found several dynamical phases of vortex motion that are different ... More

Carbon-Rich Carbon Nitride Monolayers with Dirac Cones: Dumbbell C4NDec 10 2016Two-dimensional (2D) carbon nitride materials play an important role in energy-harvesting, energy-storage and environmental applications. Recently, a new carbon nitride, 2D polyaniline (C3N) was proposed [PNAS 113 (2016) 7414-7419]. Based on the structure ... More

Magnetic particles confined in a modulated channel: structural transitions tunable by tilting a magnetic fieldJan 03 2014The ground state of colloidal magnetic particles in a modulated channel are investigated as function of the tilt angle of an applied magnetic field. The particles are confined by a parabolic potential in the transversal direction while in the axial direction ... More

Artificial molecular quantum rings: Spin density functional theory calculationsJan 09 2007The ground states of artificial molecules made of two vertically coupled quantum rings are studied within the spin density functional theory for systems containing up to 13 electrons. Quantum tunneling effects on the electronic structure of the coupled ... More

Condition of the occurrence of phase slip centers in superconducting nanowires under applied current or voltageSep 30 2003Experimental results on the phase slip process in superconducting lead nanowires are presented under two different experimental conditions: constant applied current or constant voltage. Based on these experiments we established a simple model which gives ... More

Stability of negative and positive trions in quantum wiresJan 11 2005Binding energies of negative ($X^-$) and positive trions ($X^+$) in quantum wires are studied for strong quantum confinement of carriers which results in a numerical exactly solvable model. The relative electron and hole localization has a strong effect ... More

Spatial ordering of charge and spin in quasi one-dimensional Wigner moleculesMay 16 2004ew-electron systems confined in quasi one-dimensional quantum dots are studied by the configuration interaction approach. We consider the parity symmetry of states forming Wigner molecules in large quantum dots and find that for the spin-polarized Wigner ... More

Resonant Tunneling through S- and U-shaped Graphene NanoribbonsNov 02 2009Nov 04 2009We theoretically investigate resonant tunneling through S- and U-shaped nanostructured graphene nanoribbons. A rich structure of resonant tunneling peaks are found eminating from different quasi-bound states in the middle region. The tunneling current ... More

Yukawa particles confined in a channel and subject to a periodic potential: ground state and normal modesJun 10 2010We consider a classical system of two-dimensional (2D) charged particles, which interact through a repulsive Yukawa potential $exp(-r/\lambda)/r$, confined in a parabolic channel which limits the motion of the particles in the $y$-direction. Along the ... More

Quantum anomalous Hall effect in stable 1T-YN$_2$ monolayer with a large nontrivial band gap and high Chern numberJul 06 2017Jun 23 2018The quantum anomalous Hall (QAH) effect is a topologically nontrivial phase, characterized by a non-zero Chern number defined in the bulk and chiral edge states in the boundary. Using first-principles calculations, we demonstrate the presence of the QAH ... More

New Group V Elemental Bilayers: A Tunable Structure Model with 4,6,8-atom RingsMar 10 2017Two-dimensional (2D) group V elemental materials have attracted widespread attention due to their nonzero band gap while displaying high electron mobility. Using first-principles calculations, we propose a series of new elemental bilayers with group V ... More

Gallium Bismuth Halides GaBi-X2 (X= I, Br, Cl) Monolayers with Distorted Hexagonal Framework: Novel Room-Temperature Quantum Spin Hall InsulatorsSep 22 2016Quantum Spin Hall (QSH) insulators with a large topologically nontrivial bulk gap are crucial for future applications of the QSH effect. Among these, group III-V monolayers and their halides with chair structure (regular hexagonal framework, RHF) were ... More