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Molecular quantum phase transistorApr 01 2008Apr 17 2008This paper has been withdrawn by the authors due to some technical problems in the paper.

Dimensionality driven charge density wave instability in TiS$_2$Oct 07 2013Density functional theory and density functional perturbation theory are used to investigate the electronic and vibrational properties of TiS$_2$. Within the local density approximation the material is a semi-metal both in the bulk and in the monolayer ... More

Electric field control of valence tautomeric interconversion in Cobalt dioxoleneJan 25 2011We demonstrate that the critical temperature for valence tautomeric interconversion in Cobalt dioxolene complexes can be significantly changed when a static electric field is applied to the molecule. This is achieved by effectively manipulating the redox ... More

Electron doping and magnetic moment formation in N- and C-doped MgOFeb 25 2009May 14 2009The formation of the magnetic moment in C- and N-doped MgO is the result of a delicate interplay between Hund's coupling, hybridization and Jahn-Teller distortion. The balance depends on a number of environmental variables including electron doping. We ... More

Accurate self-energy algorithm for quasi-1D systemsDec 09 2007We present a complete prescription for the numerical calculation of surface Green's functions and self-energies of semi-infinite quasi-onedimensional systems. Our work extends the results of Sanvito et al. [1] generating a robust algorithm to be used ... More

Multiprobe quantum spin Hall barsNov 28 2013Mar 11 2014We analyze electron transport in multiprobe quantum spin Hall (QSH) bars using the B\"{u}ttiker formalism and draw parallels with their quantum Hall (QH) counterparts. We find that in a QSH bar the measured resistance changes upon introducing side voltage ... More

Spin-Phonon Relaxation in Molecular Qubits from First Principles Spin DynamicsMar 04 2019The coupling between electronic spins and lattice vibrations is fundamental for driving relaxation in magnetic materials. The debate over the nature of spin-phonon coupling dates back to the 40's, but the role of spin-spin, spin-orbit and hyperfine interactions, ... More

Ab initio study on the magneto-structural properties of MnAsJan 25 2006The magnetic and structural properties of MnAs are studied with ab initio methods, and by mapping total energies onto a Heisenberg model. The stability of the different phases is found to depend mainly on the volume and on the amount of magnetic order, ... More

Dynamical Exchange Interaction From Time-Dependent Spin Density Functional TheoryJun 18 2013We report on {\it ab initio} time-dependent spin dynamics simulations for a two-center magnetic molecular complex based on time-dependent non-collinear spin density functional theory. In particular, we discuss how the dynamical behavior of the {\it ab ... More

Spin-orbit Hamiltonian for organic crystals from first principles electronic structure and Wannier functionsNov 25 2016Spin-orbit coupling in organic crystals is responsible for many spin-relaxation phenomena, going from spin diffusion to intersystem crossing. With the goal of constructing effective spin-orbit Hamiltonians to be used in multiscale approaches to the thermodynamical ... More

Exploring the limits of the self consistent Born approximation for inelastic electronic transportApr 21 2008The non equilibrium Green function formalism is today the standard computational method for describing elastic transport in molecular devices. This can be extended to include inelastic scattering by the so called self-consistent Born approximation (SCBA), ... More

Andreev reflection in two-dimensional topological insulators with either conserved or broken time-reversal symmetryFeb 22 2012Jul 19 2012We investigate Andreev reflection in two-dimensional heterojunctions formed by a superconductor in contact with a topological insulator ribbon either possessing or breaking time-reversal symmetry. Both classes of topological insulators exhibit perfect ... More

Can half metallic zincblende MnAs be grown?Apr 11 2000In this paper we investigate theoretically the ground state NiAs-type structure of MnAs and we compare the magnetic and structural properties with an hypothetical zincblende structure. A zincblende structure can be obtained, in principle, from the diluted ... More

Contact-induced spin polarization in carbon nanotubesNov 28 2003Motivated by the possibility of combining spintronics with molecular structures, we investigate the conditions for the appearance of spin-polarization in low-dimensional tubular systems by contacting them to a magnetic substrate. We derive a set of general ... More

Electron transport across electrically switchable magnetic moleculesMay 11 2009We investigate the electron transport properties of a model magnetic molecule formed by two magnetic centers whose exchange coupling can be altered with a longitudinal electric field. In general we find a negative differential conductance at low temperatures ... More

Resonant magnetoresistance in organic spin-valvesOct 31 2006We investigate theoretically the effects of surface states over the magnetoresistance of Ni-based organic spin-valves. In particular we perform {\it ab initio} electronic transport calculations for a benzene-thiolate molecule chemically attached to a ... More

Do As antisites destroy the ferromagnetism of (Ga,Mn)As?Nov 22 2000The effect of the inclusion of As antisites in the diluted magnetic semiconductor (Ga,Mn)As is studied within density functional theory in the local spin density approximation. In the case of homogeneous distribution of Mn ions we find that the ferromagnetism ... More

Molecular-Spintronics: the art of driving spin through moleculesMay 09 2006Spintronics is the ability of injecting, manipulating and detecting electron spins into solid state systems. Molecular-electronics investigates the possibility of making electronic devices using organic molecules. Traditionally these two burgeoning areas ... More

Ab-initio transport theory for digital ferromagnetic heterostructuresAug 25 2001MnAs/GaAs superlattices, made by $\delta$-doping GaAs with Mn, are known as digital ferromagnetic heterostructures. Here we present a theoretical density functional study of the electronic, magnetic and transport properties of such heterostructures. In ... More

Non-equilibrium magnetic fields in ab initio spin dynamicsApr 21 2016Starting from the continuity equation for the magnetization in time-dependent spin-density functional theory, we derive an expression for the effective time-dependent magnetic fields driving the out-of-equilibrium spin dynamics in magnetic systems. We ... More

Charge carrier mobility in hybrid halide perovskitesNov 28 2014May 19 2015The charge transport properties of hybrid halide perovskites are investigated with a combination of density functional theory including van der Waals interaction and the Boltzmann theory for diffusive transport in the relaxation time approximation. We ... More

A pertubative approach to the Kondo effect in magnetic atoms on nonmagnetic substratesApr 14 2011Recent experimental advances in scanning tunneling microscopy make the measurement of the conductance spectra of isolated and magnetically coupled atoms on nonmagnetic substrates possible. Notably these spectra are characterized by a competition between ... More

The magnetism of wurtzite CoO nanoclustersAug 25 2009The possibility that the apparent room temperature ferromagnetism, often measured in Co-doped ZnO, is due to uncompensated spins at the surface of wurtzite CoO nanoclusters is investigated by means of a combination of density functional theory and Monte ... More

Detection of the electrostatic spin crossover effect in magnetic moleculesApr 17 2013Scanning tunneling microscopy (STM) can be used to detect inelastic spin transitions in magnetic nano-structures comprising only a handful of atoms. Here we demonstrate that STM can uniquely identify the electrostatic spin crossover effect, whereby the ... More

Magnetism and Antiferroelectricity in MgB$_6$Mar 08 2012We report on a density functional theory study demonstrating the coexistence of weak ferromagnetism and antiferroelectricity in boron-deficient MgB6. A boron vacancy produces an almost one dimensional extended molecular orbital, which is responsible for ... More

Different origin of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)NJun 21 2004The mechanism for the ferromagnetic order of (Ga,Mn)As and (Ga,Mn)N is extensively studied over a vast range of Mn concentrations. We calculate the electronic structures of these materials using density functional theory in both the local spin density ... More

Self-interaction effects in (Ga,Mn)As and (Ga,Mn)NFeb 10 2003Jul 02 2004The electronic structures of Mn-doped zincblende GaAs and wurtzite GaN are calculated using both standard local-density functional theory (LSDA), and a novel pseudopotential self-interaction-corrected approach (pseudo-SIC), able to account for the effects ... More

First principles study of the origin and nature of ferromagnetism in (Ga,Mn)AsNov 02 2000The properties of diluted Ga$_{1-x}$Mn$_x$As are calculated for a wide range of Mn concentrations within the local spin density approximation of density functional theory. M\"ulliken population analyses and orbital-resolved densities of states show that ... More

The ground state of a spin-crossover molecule calculated by diffusion Monte CarloApr 24 2012Spin crossover molecules have recently emerged as a family of compounds potentially useful for implementing molecular spintronics devices. The calculations of the electronic properties of such molecules is a formidable theoretical challenge as one has ... More

Phenomenology of Andreev reflection from first-principles transport theoryOct 27 2014We study Andreev reflection in normal metal-superconductor junctions by using an extended Blonder-Tinkham-Klapwijk model combined with transport calculations based on density functional theory. Starting from a parameter-free description of the underlying ... More

Spin-pumping and inelastic electron tunneling spectroscopy in topological insulatorsSep 07 2012Jun 07 2013We demonstrate that a quantum spin Hall current, spontaneously generated at the edge of a two-dimensional topological insulator, acts as a source of spin-pumping for a magnetic impurity with uniaxial anisotropy. One can then manipulate the impurity spin ... More

Topological surface states scattering in AntimonyJul 19 2012Nov 05 2012In this work we study the topologically protected states of the Sb(111) surface by using ab-initio transport theory. In the presence of a strong surface perturbation we obtain standing-wave states resulting from the superposition of spin-polarized surface ... More

Effects of edge chemistry doping on graphene nanoribbon mobilityJul 24 2011Doping of semiconductor is necessary for various device applications. Exploiting chemistry at its reactive edges was shown to be an effective way to dope an atomically thin graphene nanoribbon (GNR) for realizing new devices in recent experiments. The ... More

Bias asymmetry in the conductance profile of magnetic ions on surfaces probed by scanning tunneling microscopyMar 28 2012The conductance profiles of magnetic transition metal atoms, such as Fe, Co and Mn, deposited on surfaces and probed by a scanning tunneling microscope (STM), provide detailed information on the magnetic excitations of such nano-magnets. In general the ... More

On the Newtonian origin of the spin motive force in ferromagnetic atomic wiresAug 08 2007Dec 10 2007We demonstrate numerically the existence of a spin-motive force acting on spin-carriers when moving in a time and space dependent internal field. This is the case of electrons in a one-dimensional wires with a precessing domain wall. The effect can be ... More

Current-driven magnetic rearrangements in spin-polarized point contactsMay 05 2005A new method for investigating the dynamics of atomic magnetic moments in current-carrying magnetic point contacts under bias is presented. This combines the non-equilibrium Green's function (NEGF) method for evaluating the current and the charge density ... More

Non-equilibrium magnetic fields in ab initio spin dynamicsApr 21 2016Nov 18 2016Starting from the continuity equation for the magnetization in time-dependent spin-density functional theory, we derive an expression for the effective time-dependent magnetic fields driving the out-of-equilibrium spin dynamics in magnetic systems. We ... More

Designing magnetism in Fe-based Heusler alloys: a machine learning approachJun 06 2017Combining material informatics and high-throughput electronic structure calculations offers the possibility of a rapid characterization of complex magnetic materials. Here we demonstrate that datasets of electronic properties calculated at the ab initio ... More

Resonant electronic states and I-V curves of Fe/MgO/Fe(100) tunnel junctionsAug 06 2008The bias dependence of the tunnel magnetoresistance (TMR) of Fe/MgO/Fe tunnel junctions is investigated theoretically with a fully self-consistent scheme that combines the non-equilibrium Green's functions method with density functional theory. At voltages ... More

The role of spin-orbit interaction in the ultrafast demagnetization of small iron clustersNov 03 2015The ultra-fast demagnetization of small iron clusters initiated by an intense optical excitation is studied with time-dependent spin density functional theory (TDSDFT). In particular we investigate the effect of the spin-orbit interaction on the onset ... More

Gate controlled spin pumping at a quantum spin Hall edgeNov 28 2013We propose a four-terminal device designed to manipulate by all electrical means the spin of a magnetic adatom positioned at the edge of a quantum spin Hall insulator. We show that an electrical gate, able to tune the interface resistance between a quantum ... More

Femtosecond spin current pulses generated by the non-thermal spin-dependent Seebeck effect and interacting with ferromagnets in spin valvesJun 11 2016Jul 25 2016Using the sensitivity of magneto-induced second harmonic generation to spin currents (SC), we demonstrate in Fe/Au/Fe/MgO(001) pseudo spin valves the generation of 250 fs-long SC pulses. Their temporal profile indicates that superdiffusive hot electron ... More

Charge transfer energies of benzene physisorbed on a graphene sheet from constrained density functional theoryOct 27 2015Constrained density functional theory (CDFT) is used to evaluate the energy level alignment of a benzene molecule as it approaches a graphene sheet. Within CDFT the problem is conveniently mapped onto evaluating total energy differences between different ... More

Origin of the n-type and p-type conductivity of MoS2 monolayers on a SiO2 substrateJan 11 2013Ab-initio density functional theory calculations are performed to study the electronic properties of a MoS2 monolayer deposited over a SiO2 substrate in the presence of interface impurities and defects. When MoS2 is placed on a defect-free substrate the ... More

Spin-flip inelastic electron tunneling spectroscopy in atomic chainsMar 14 2011We present a theoretical study of the spin transport properties of mono-atomic magnetic chains with a focus on the spectroscopical features of the I-V curve associated to spin-flip processes. Our calculations are based on the s-d model for magnetism with ... More

Electric Field Effects on Armchair MoS2 NanoribbonsAug 28 2013{\it Ab initio} density functional theory calculations are performed to investigate the electronic structure of MoS$_2$ armchair nanoribbons in the presence of an external static electric field. Such nanoribbons, which are nonmagnetic and semiconducting, ... More

Electrical control of spin dynamics in finite one-dimensional systemsJun 18 2011We investigate the possibility of the electrical control of spin transfer in monoatomic chains incorporating spin-impurities. Our theoretical framework is the mixed quantum-classical (Ehrenfest) description of the spin dynamics, in the spirit of the s-d-model, ... More

Magnetic interaction of Co ions near the {10\bar{1}0} ZnO surfaceMar 12 2010Co-doped ZnO is the prototypical dilute magnetic oxide showing many of the characteristics of ferromagnetism. The microscopic origin of the long range order however remains elusive, since the conventional mechanisms for the magnetic interaction, such ... More

Magnetism of CoO polymorphsJan 07 2008Jul 01 2008A microscopic explanation for the room temperature ferromagnetism in diluted ZnO:Co is at present rather elusive. Although standard secondary phases can usually be ruled out, it is less clear whether regions with high Co concentration coexist with undoped ... More

Single atom anisotropic magnetoresistance on a topological insulator surfaceMay 12 2014Mar 15 2015We demonstrate single atom anisotropic magnetoresistance on the surface of a topological insulator, arising from the interplay between the helical spin-momentum-locked surface electronic structure and the hybridization of the magnetic adatom states. Our ... More

Coexistance of giant tunneling electroresistance and magnetoresistance in an all-oxide magnetic tunnel junctionFeb 22 2012We demonstrate with first-principles electron transport calculations that large tunneling magnetoresistance (TMR) and tunneling electroresistance (TER) effects can coexist in an all-oxide device. The TMR originates from the symmetry-driven spin filtering ... More

Strain-induced Weyl and Dirac states and direct-indirect gap transitions in group-V materialsJan 24 2018We perform comprehensive density-functional theory calculations on strained two-dimensional phosphorus (P), arsenic (As) and antimony (Sb) in the monolayer, bilayer, and bulk $\alpha$-phase, from which we compute the key mechanical and electronic properties ... More

A simple descriptor for energetics at fcc-bcc metal interfacesFeb 08 2018We develop a new and user-friendly method for calculating interface energies from first-principles. Our approach avoids problems that derive from the numerical differences between bulk and slab calculations, such as the number of k-points along the direction ... More

First-principles spin-transfer torque in CuMnAs$|$GaP$|$CuMnAs junctionsNov 22 2016We demonstrate that an all-antiferromagnetic tunnel junction with current perpendicular to the plane geometry can be used as an efficient spintronics device with potential high frequency operation. By using state-of-the-art density functional theory combined ... More

Proximity induced topological state in grapheneJul 15 2014The appearance of topologically protected states at the surface of an ordinary insulator is a rare occurrence and to date only a handful of materials are known for having this property. An intriguing question concerns the possibility of forming topologically ... More

Ab-initio transport across Bismuth Selenide surface barriersMar 11 2014Dec 17 2014We investigate the effect of potential barriers in the form of step edges on the scattering properties of Bi$_2$Se$_3$(111) topological surface states by means of large-scale ab-initio transport simulations. Our results demonstrate the suppression of ... More

Theoretical evaluation of [V$^{IV}$(α-C$_3$S$_5$)]${^2-}$ as nuclear-spin sensitive single-molecule spin transistorDec 23 2016Jun 01 2017In a straightforward application of molecular nanospintronics to quantum computing, single-molecule spin transistors can be used to measure and control nuclear spin qubits. A jump in the conductance occurs when the electronic spin inverts its polarization, ... More

Adaptive Robust Traffic Engineering in Software Defined NetworksDec 15 2017One of the key advantages of Software-Defined Networks (SDN) is the opportunity to integrate traffic engineering modules able to optimize network configuration according to traffic. Ideally, network should be dynamically reconfigured as traffic evolves, ... More

Current-induced energy barrier suppression for electromigration from first principlesJul 04 2011We present an efficient method for evaluating current-induced forces in nanoscale junctions, which naturally integrates into the non-equilibrium Green's function formalism implemented within density functional theory. This allows us to perform dynamical ... More

Efficient spin injection and giant magnetoresistance in Fe/MoS$_2$/Fe junctionsApr 14 2014Jul 15 2014We demonstrate giant magnetoresistance in Fe/MoS$_2$/Fe junctions by means of \textit{ab-initio} transport calculations. We show that junctions incorporating either a mono- or a bi-layer of MoS$_2$ are metallic and that Fe acts as an efficient spin injector ... More

Non-trivial spatial dependence of the spin torques in L1$_0$ FePt-based tunnelling junctionsOct 09 2018We present an {\it ab-initio} study of the spin-transfer torque in a Fe/MgO/FePt/Fe magnetic tunnel junctions. We consider a FePt film with a thickness up to six unit cells, either in direct contact with the MgO spacer or with an intercalated ultra-thin ... More

Wannier-function-based constrained DFT with nonorthogonality-correcting Pulay forces in application to the reorganization effects in graphene-adsorbed pentaceneFeb 05 2018Pulay terms arise in the Hellman-Feynman forces in electronic structure calculations when one employs a basis set made of localized orbitals that move with their host atoms. If the total energy of the system depends on a subspace population, defined in ... More

Large bias-dependent magnetoresistance in all-oxide magnetic tunnel junctions with a ferroelectric barrierOct 05 2010All-oxide magnetic tunnel junctions (MTJs) incorporating functional materials as insulating barriers have the potential of becoming the founding technology for novel multi-functional devices. We investigate, by first-principles density functional theory, ... More

Topological tuning in three-dimensional Dirac semimetalsAug 15 2014Dec 17 2014We study with first-principles methods the interplay between bulk and surface Dirac fermions in three dimensional Dirac semimetals. By combining density functional theory with the coherent potential approximation, we reveal a topological phase transition ... More

Ab-initio study on the possible doping strategies for MoS$_2$ monolayersApr 30 2013Density functional theory is used to systematically study the electronic and magnetic properties of doped MoS$_2$ monolayers, where the dopants are incorporated both via S/Mo substitution or as adsorbates. Among the possible substitutional dopants at ... More

On-site approximation for spin-orbit coupling in LCAO density functional methodsJan 05 2006Oct 09 2007We propose a computational method that simplifies drastically the inclusion of spin-orbit interaction in density functional theory implemented on localised atomic orbital basis sets. Our method is based on a well-known procedure for obtaining pseudopotentials ... More

Monte-Carlo phase diagram of a Hubbard-Peierls model in the search for spin crossover transition in $π$-conjugated polymersDec 16 2010We present a Monte Carlo study of the finite temperature properties of an extended Hubbard-Peierls model describing one dimensional $\pi$-conjugated polymers. The model incorporates electron-phonon and hyperfine interaction and it is solved at the mean ... More

Magneto-mechanical interplay in spin-polarized point contactsJan 10 2006We investigate the interplay between magnetic and structural dynamics in ferromagnetic atomic point contacts. In particular, we look at the effect of the atomic relaxation on the energy barrier for magnetic domain wall migration and, reversely, at the ... More

Revealing the role of organic cations in hybrid halide perovskites CH3NH3PbI3Oct 30 2014Jan 15 2015The hybrid halide perovskite CH$_{3}$NH$_{3}$PbI$_{3}$ has enabled solar cells to reach an efficiency of about 18\%, demonstrating a pace for improvements with no precedents in the solar energy arena. Despite such explosive progress, the microscopic origin ... More

Atomistic Simulations of Highly Conductive Molecular Transport Junctions Under Realistic ConditionsMar 20 2013We report state-of-the-art atomistic simulations combined with high-fidelity conductance calculations to probe structure-conductance relationships in Au-benzenedithiolate(BDT)-Au junctions under elongation. Our results demonstrate that large increases ... More

Electronic Transport Through EuO Spin Filter Tunnel JunctionsJul 09 2012Epitaxial spin filter tunnel junctions based on the ferromagnetic semiconductor europium monoxide, EuO, are investigated by means of density functional theory. In particular, we focus on the spin transport properties of Cu(100)/EuO(100)/Cu(100) junctions. ... More

Structural Origins of Conductance Fluctuations in Gold-Thiolate Molecular Transport JunctionsMar 01 2013We report detailed atomistic simulations combined with high-fidelity conductance calculations to probe the structural origins of conductance fluctuations in thermally evolving Au-benzene-1,4-dithiolate-Au junctions. We compare the behavior of structurally ... More

Electronic properties of bulk and thin film SrRuO$_3$: a search for the metal-insulator transitionJun 08 2008We calculate the properties of the 4$d$ ferromagnet SrRuO$_3$ in bulk and thin film form with the aim of understanding the experimentally observed metal to insulator transition at reduced thickness. Although the spatial extent of the 4$d$ orbitals is ... More

Spin-filtering efficiency of ferrimagnetic spinels CoFe2O4 and NiFe2O4Jan 11 2013We assess the potential of the ferrimagnetic spinel ferrites CoFe2O4 and NiFe2O4 to act as spin filtering barriers in magnetic tunnel junctions. Our study is based on the electronic structure calculated by means of first-principles density functional ... More

Search for alternative magnetic tunnel junctions based on all-Heusler stacksMay 18 2018By imposing the constraints of structural compatibility, stability and a large tunneling magneto-resistance, we have identified the Fe$_3$Al/BiF$_3$/Fe$_3$Al stack as a possible alternative to the well-established FeCoB/MgO/FeCoB in the search for a novel ... More

Proposal for a dual spin filter based on [VO(C$_3$S$_4$O)$_2$]$^{2-}$Dec 18 2017Polynuclear magnetic molecules often present dense transmission spectra with many overlapping conduction spin channels. Single-metal complexes display a sparser density of states, which in the presence of a fixed external magnetic field makes them interesting ... More

Ab-initio methods for spin-transport at the nanoscale levelMar 17 2005Apr 08 2005Recent advances in atomic and nano-scale growth and characterization techniques have led to the production of modern magnetic materials and magneto-devices which reveal a range of new fascinating phenomena. The modeling of these is a tough theoretical ... More

Ferromagnetism and metallic state in digital (Ga,Mn)As heterostructuresMay 27 2003We present an extensive density functional theory study of the electronic, magnetic and transport properties of GaAs and AlAs digital ferromagnetic heterostructures. These can be obtained by $\delta$-doping with Mn the GaAs layers of a GaAs/AlAs superlattice. ... More

Functionalized nanopore-embedded electrodes for rapid DNA sequencingAug 29 2007The determination of a patient's DNA sequence can, in principle, reveal an increased risk to fall ill with particular diseases [1,2] and help to design "personalized medicine" [3]. Moreover, statistical studies and comparison of genomes [4] of a large ... More

AFLOW-CHULL: Cloud-oriented platform for autonomous phase stability analysisJun 18 2018$\textit{A priori}$ prediction of phase stability of materials is a challenging practice, requiring knowledge of all energetically-competing structures at formation conditions. Large materials repositories $\unicode{x2014}$ housing properties of both ... More

Quantum Teleportation with Continuous Variables: a surveyApr 05 2006Oct 12 2006Very recently we have witnessed a new development of quantum information, the so-called continuous variable (CV) quantum information theory. Such a further development has been mainly due to the experimental and theoretical advantages offered by CV systems, ... More

Quadratic interaction functional for systems of conservation laws: a case studyNov 12 2013We prove a quadratic interaction estimate for wavefront approximate solutions to the triangular system of conservation laws \[ \begin{cases} u_t + \tilde f(u,v)_x = 0, \cr v_t - v_x = 0. \end{cases} \] This quadratic estimate has been used in the literature ... More

A note on the existence of $L^2$ valued solutions for a hyperbolic system with boundary conditionsNov 13 2018Feb 08 2019We prove existence of $L^2$-weak solutions of a quasilinear wave equation with boundary conditions.This is done using a vanishing viscosity approximation with mixed Dirichlet-Neumann boundary conditions. In this setting we obtain a uniform a priori estimate ... More

On a quadratic functional for scalar conservation lawsNov 12 2013We prove a quadratic interaction estimate for approximate solutions to scalar conservation laws obtained by the wavefront tracking approximation or the Glimm scheme. This quadratic estimate has been used in the literature to prove the convergence rate ... More

Hydrodynamic Limit for an Anharmonic Chain under Boundary TensionFeb 06 2018Jun 11 2018We study the hydrodynamic limit for the isothermal dynamics of an anharmonic chain under hyperbolic space-time scaling under varying tension. The temperature is kept constant by a contact with a heat bath, realised via a stochastic momentum-preserving ... More

Hydrodynamic Limit for an Anharmonic Chain under Boundary TensionFeb 06 2018We study the hydrodynamic limit for a one dimensional isothermal anharmonic finite chain in Lagrangian coordinates with hyperbolic space-time scaling. The temperature is kept constant by putting the chain in contact with a heat bath, realised via a stochastic ... More

Quadratic interaction functional for general systems of conservation lawsDec 19 2014For the Glimm scheme approximation $u_\epsilon$ to the solution of the system of conservation laws in one space dimension \begin{equation*} u_t + f(u)_x = 0, \qquad u(0,x) = u_0(x) \in \mathbb R^n, \end{equation*} with initial data $u_0$ with small total ... More

Stretching of BDT-gold molecular junctions: thiol or thiolate termination?Oct 03 2014It is often assumed that the hydrogen atoms in the thiol groups of a benzene-1,4-dithiol dissociate when Au-benzene-1,4-dithiol-Au junctions are formed. We demonstrate, by stability and transport properties calculations, that this assumption can not be ... More

Electron localization in pure and defective ceria by a unified LDA+U approachDec 23 2003The electronic and structural properties of pure and defective cerium oxide are investigated using a unified LDA+U approach which allows to treat the different valence states of Ce occurring for different stoichiometries on a same ground, without any ... More

An in- and ex-situ TEM study into the oxidisation of titanium (IV) sulphideMay 29 2015The degradation of liquid dispersed titanium (IV) sulphide (TiS$_2$) is studied from the point of view of oxidisation. TiS$_2$ is a layered two-dimensional nanomaterial, with potential for energy storage applications. However, flakes in dispersion were ... More

Gate-tunable quantum oscillations in ambipolar Cd3As2 thin filmsDec 14 2014Sep 29 2015Electrostatic doping in materials can lead to various exciting electronic properties, such as metal-insulator transition and superconductivity, by altering the Fermi level position or introducing exotic phases. Cd3As2, a three-dimensional (3D) analog ... More

Observation of quasi-two-dimensional Dirac fermions in ZrTe5Oct 04 2015Nov 14 2016Since the discovery of graphene, layered materials have attracted extensive interests owing to their unique electronic and optical characteristics. Among them, Dirac semimetal, one of the most appealing categories, has been a long-sought objective in ... More

Spin-valve Effect in NiFe/MoS2/NiFe JunctionsFeb 22 2015Aug 15 2015Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have been recently proposed as appealing candidate materials for spintronic applications owing to their distinctive atomic crystal structure and exotic physical properties arising from ... More

Performance of the Pierre Auger Fluorescence Detector and Analysis of well recontructed eventsAug 25 2003The Pierre Auger Observatory is designed to elucidate the origin and nature of Ultra High Energy Cosmic Rays using a hybrid detection technique. A first run of data taking with a prototype version of both detectors (the so called Engineering Array) took ... More

Performance of the CMS Tracker Optical Links and Future Upgrade Using Bandwidth Efficient Digital ModulationApr 30 2010(Abridged version) The CMS experiment at the LHC will begin operation in 2007. The CMS Tracker sub-detector, comprises ~10 million detector channels read out by ~40 000 analog optical links. The optoelectronic components have been designed to meet the ... More

Stability and Instability of Extreme Reissner-Nordström Black Hole Spacetimes for Linear Scalar Perturbations IIOct 10 2011This paper contains the second part of a two-part series on the stability and instability of extreme Reissner-Nordstrom spacetimes for linear scalar perturbations. We continue our study of solutions to the linear wave equation on a suitable globally hyperbolic ... More

Stability and Instability of Extreme Reissner-Nordström Black Hole Spacetimes for Linear Scalar Perturbations IOct 10 2011We study the problem of stability and instability of extreme Reissner-Nordstrom spacetimes for linear scalar perturbations. Specifically, we consider solutions to the linear wave equation on a suitable globally hyperbolic subset of such a spacetime, arising ... More

The Wave Equation on Extreme Reissner-Nordström Black Hole Spacetimes: Stability and Instability ResultsJun 02 2010Oct 10 2011We consider solutions to the linear wave equation on a suitable globally hyperbolic subset of an extreme Reissner-Nordstrom spacetime, arising from regular initial data prescribed on a Cauchy hypersurface crossing the future event horizon. We obtain boundedness, ... More

Nonlinear instability of scalar fields on extremal black holesApr 16 2013We prove a new type of finite time blow-up for a class of semilinear wave equations on extremal black holes. The initial data can be taken to be arbitrarily close to the trivial data. The first singularity occurs along the (degenerate) future event horizon. ... More

Phenomenology of TMDsDec 04 2014We present a review of current Transverse Momentum Dependent (TMD) phenomenology focusing our attention on the unpolarized TMD parton distribution function and the Sivers function. The paper introduces and comments about the new Collins-Soper-Sterman ... More