Results for "Roland Wiesendanger"

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Long spin relaxation times in a transition metal atom in direct contact to a metal substrateDec 14 2017Long spin relaxation times are a prerequisite for the use of spins in data storage or nanospintronics technologies. An atomic-scale solid-state realization of such a system is the spin of a transition metal atom adsorbed on a suitable substrate. For the ... More
Itinerant Nature of Atom-Magnetization Excitation by Tunneling ElectronsOct 06 2010Nov 04 2010We have performed single-atom magnetization curve (SAMC) measurements and inelastic scanning tunneling spectroscopy (ISTS) on individual Fe atoms on a Cu(111) surface. The SAMCs show a broad distribution of magnetic moments with $\unit[3.5]{\mu_{\rm B}}$ ... More
Pattern formation in skyrmionic materials with anisotropic environmentsMar 03 2016Magnetic skyrmions have attracted broad attention during recent years because they are regarded as promising candidates as bits of information in novel data storage devices. A broad range of theoretical and experimental investigations have been conducted ... More
STM study of the preparation of clean Ta(110) and the subsequent growth of two-dimensional Fe islandsApr 07 2016Jun 07 2016This report deals with the preparation of a clean Ta(110) surface, investigated by means of scanning tunneling microscopy/spectroscopy as well as by low-energy electron diffraction and Auger electron spectroscopy. The surface initially exhibits a surface ... More
Computing with spins and magnetsNov 25 2014The possible use of spin and magnets in place of charge and capacitors to store and process information is well known. Magnetic tunnel junctions are being widely investigated and developed for magnetic random access memories. These are two terminal devices ... More
Domain imaging across the magneto-structural phase transition in Fe$_{1+y}$TeNov 30 2017The investigation of the magnetic phase transitions in the parent compounds of Fe-based superconductors is regarded essential for an understanding of the pairing mechanism in the related superconducting compounds. Even though the chemical and electronic ... More
Pinning and movement of individual nanoscale magnetic skyrmions via defectsJan 20 2016An understanding of the pinning of magnetic skyrmions to defects is crucial for the development of future spintronic applications. While pinning is desirable for a precise positioning of magnetic skyrmions it is detrimental when they are to be moved through ... More
Tuning non-collinear magnetic states by hydrogenationDec 17 2018Two different superstructures form when atomic H is incorporated in the Fe monolayer on Ir(111). Depending on the amount of H provided, either a highly ordered p(2x2) hexagonal superstructure or an irregular roughly square structure is created. We present ... More
Probing the Nanoskyrmion Lattice on Fe/Ir(111) with Magnetic Exchange Force MicroscopyApr 10 2017We demonstrate that the magnetic nanoskyrmion lattice on the Fe monolayer on Ir(111) and the positions of the Fe atoms can be resolved simultaneously using magnetic exchange force microscopy. Thus, the relation between magnetic and atomic structure can ... More
Coupling of Coexisting Non-Collinear Spin States in the Fe Monolayer on Re(0001)May 17 2016Jun 22 2016Spin-polarized scanning tunneling microscopy is used to investigate the magnetic state of the Fe monolayer on Re(0001). Two coexisting atomic-scale non-collinear spin textures are observed with a sharp transition between them on the order of one atomic ... More
Probing weakly hybridized magnetic molecules by spin-polarized tunnelingJun 11 2019Advances in molecular spintronics rely on the in-depth characterization of the molecular building blocks in terms of their electronic and, more importantly, magnetic properties. For this purpose, inert substrates that interact only weakly with adsorbed ... More
Analysis of the inelastic contribution to atomic spin excitation spectroscopyFeb 18 2011We investigate the dependence of the inelastic spin excitation contribution to scanning tunneling spectroscopy recorded above Fe adsorbates on the InSb(110) surface at subkelvin temperatures, on bulk doping and tunnel junction resistance. To explain our ... More
Localized spin waves in isolated $kπ$ skyrmionsOct 15 2018The localized magnon modes of isolated $k\pi$ skyrmions on a field-polarized background are analyzed based on the Landau-Lifshitz-Gilbert equation within the terms of an atomistic classical spin model, with system parameters based on the Pd/Fe biatomic ... More
Effective damping enhancement in noncollinear spin structuresMay 04 2018Oct 15 2018Damping mechanisms in magnetic systems determine the lifetime, diffusion and transport properties of magnons, domain walls, magnetic vortices, and skyrmions. Based on the phenomenological Landau-Lifshitz-Gilbert equation, here the effective damping parameter ... More
Impact of the skyrmion spin texture on magnetoresistanceJan 31 2017We investigate the impact of the local spin texture on the differential conductance by scanning tunneling microscopy. In the focus is the previously found non-collinear magnetoresistance, which originates from spin mixing effects upon electron hopping ... More
Controlling the Local Spin-Polarization at the Organic-Ferromagnetic InterfaceMay 28 2010By means of ab initio calculations and spin-polarized scanning tunneling microscopy experiments we show how to manipulate the local spin-polarization of a ferromagnetic surface by creating a complex energy dependent magnetic structure. We demonstrate ... More
Evidence for a two-fold symmetric superconducting gap in a monolayer of FeSe$_{0.5}$Te$_{0.5}$ on a topological insulatorAug 12 2016We present our investigations on the superconducting properties of monolayers of FeSe$_{0.5}$Te$_{0.5}$ grown on the 3D topological insulator Bi$_{2}$Se$_{1.2}$Te$_{1.8}$ using low temperature scanning tunneling spectroscopy (STS). While the morphology ... More
Magnetic domain walls in strain-patterned ultrathin filmsAug 24 2018We present a comparison of the characteristics of the magnetic domain walls in an atomic monolayer of Co on Pt(111) and a Ni/Fe atomic bilayer on Ir(111), based on spin-polarized scanning tunneling microscopy measurements. In both cases, the films exhibit ... More
Atomic-Scale Interface Engineering of Majorana Edge Modes in a 2D Magnet-Superconductor Hybrid SystemSep 12 2018Topological superconductors are predicted to harbor exotic boundary states - Majorana zero-energy modes - whose non-Abelian braiding statistics present a new paradigm for the realization of topological quantum computing. Using low-temperature scanning ... More
Symmetry breaking in spin spirals and skyrmions by in-plane and canted magnetic fieldsMar 18 2016The influence of in-plane and canted magnetic fields on spin spirals and skyrmions in atomic bilayer islands of palladium and iron on an Ir(111) substrate is investigated by scanning tunnelling microscopy at low temperatures. It is shown that the spin ... More
Field-Dependent Size and Shape of Single Magnetic SkyrmionsApr 07 2015The atomic-scale spin structure of individual isolated skyrmions in an ultrathin film is investigated in real space by spin-polarized scanning tunneling microscopy. Their axial symmetry as well as their unique rotational sense is revealed by using both ... More
Tailoring non-collinear magnetism by misfit dislocation linesOct 21 2016The large epitaxial stress induced by the misfit between a triple atomic layer Fe film and an Ir(111) substrate is relieved by the formation of a dense dislocation line network. Spin-polarized scanning tunneling microscopy (SP-STM) investigations show ... More
Report on imaging of individual skyrmions of MML systems made by different techniquesSep 27 2016Deliverable 1.1 is a report on imaging of individual skyrmions of MML systems made by different techniques. This deliverable falls within work package 1 (WP1:Static equilibrium properties of interface induced skyrmions in magnetic films and multilayers) ... More
Set-up of a High-Resolution 300 mK Atomic Force Microscope in an Ultra-High Vacuum Compatible 3He/10T CryostatJun 20 2016The design of an atomic force microscope with an all-fiber interferometric detection scheme capable of atomic resolution at about 500 mK is presented. The microscope body is connected to a small pumped 3He reservoir with a base temperature of about 300 ... More
Isolated zero field sub-10 nm skyrmions in ultrathin Co filmsMar 06 2019Due to their exceptional topological and dynamical properties magnetic skyrmions - localized stable spin structures on the nanometre scale - show great promise for future spintronic applications. To become technologically competitive, isolated skyrmions ... More
Controlled creation and stability of kπ-skyrmions on a discrete latticeFeb 26 2018We determine sizes and activation energies of k{\pi}-skyrmions on a discrete lattice using the Landau- Lifshitz-Gilbert equation and the geodesic nudged elastic band method. The employed atomic material parameters are based on the skyrmionic material ... More
Electric field driven switching of individual magnetic skyrmionsJan 12 2016Controlling magnetism with electric fields is a key challenge to develop future energy-efficient devices, however, the switching between inversion symmetric states, e.g. magnetization up and down as used in current technology, is not straightforward, ... More
Revealing Sub-Surface Vibrational Modes by Atom-Resolved Damping Force SpectroscopyApr 17 2009We propose to use the damping signal of an oscillating cantilever in dynamic atomic force microscopy as a noninvasive tool to study the vibrational structure of the substrate. We present atomically resolved maps of damping in carbon nanotube peapods, ... More
Stochastic dynamics and pattern formation of geometrically confined skyrmionsMay 10 2019Ensembles of magnetic skyrmions in confined geometries are shown to exhibit thermally driven motion on two different time scales. The intrinsic fluctuating dynamics ($t\sim 1~$ps) is governed by short-range symmetric and antisymmetric exchange interactions, ... More
Combined feedback and sympathetic cooling of a mechanical oscillator coupled to ultracold atomsJun 13 2018A promising route to novel quantum technologies are hybrid quantum systems, which combine the advantages of several individual quantum systems. We have realized a hybrid atomic-mechanical experiment consisting of a SiN membrane oscillator cryogenically ... More
Temperature-induced increase of spin spiral periodsMar 31 2017Spin-polarized scanning tunneling microscopy investigations reveal a significant increase of the magnetic period of spin spirals in three-atomic-layer-thick Fe films on Ir(111), from about 4nm at 8K to about 65nm at room temperature. We attribute this ... More
Spin-polarization of platinum (111) induced by the proximity to cobalt nanostripesOct 11 2010We measured a spin polarization above a Pt (111) surface in the vicinity of a Co nanostripe by spin-polarized scanning tunneling spectroscopy. The spin polarization is exponentially decaying away from the Pt/Co interface and is detectable at distances ... More
Nano-scale magnetic skyrmions and target states in confined geometriesJan 21 2019Research on magnetic systems with broken inversion symmetry has been stimulated by the experimental proof of particle-like configurations known as skyrmions, whose non-trivial topological properties make them ideal candidates for spintronic technology. ... More
Domain walls and Dzyaloshinskii-Moriya interaction in epitaxial Co/Ir(111) and Pt/Co/Ir(111)Feb 06 2018We use spin-polarized scanning tunneling microscopy and density functional theory (DFT) to study domain walls (DWs) and the Dzyaloshinskii-Moriya interaction (DMI) in epitaxial films of Co/Ir(111) and Pt/Co/Ir(111). Our measurements reveal DWs with fixed ... More
Electrical detection of magnetic skyrmions by non-collinear magnetoresistanceJul 15 2015Magnetic skyrmions are localised non-collinear spin textures with high potential for future spintronic applications. Skyrmion phases have been discovered in a number of materials and a focus of current research is the preparation, detection, and manipulation ... More
Giant magnetization canting due to symmetry breaking in zigzag Co chains on Ir(001)Sep 24 2013We demonstrate a canted magnetization of biatomic zigzag Co chains grown on the 5 x 1 reconstructed Ir(001) surface using density functional theory calculations and spin-polarized scanning tunneling microscopy (SP-STM) experiments. Biatomic Co chains ... More
Spin- and energy-dependent tunneling through a single molecule with intramolecular spatial resolutionMay 26 2010We investigate the spin- and energy dependent tunneling through a single organic molecule (CoPc) adsorbed on a ferromagnetic Fe thin film, spatially resolved by low-temperature spin-polarized scanning tunneling microscopy. Interestingly, the metal ion ... More
Imaging correlated wave functions of few-electron quantum dots: Theory and scanning tunneling spectroscopy experimentsAug 02 2007We show both theoretically and experimentally that scanning tunneling spectroscopy (STS) images of semiconductor quantum dots may display clear signatures of electron-electron correlation. We apply many-body tunneling theory to a realistic model which ... More
Correlation Effects in Wave Function Mapping of Molecular Beam Epitaxy Grown Quantum DotsJul 31 2007We investigate correlation effects in the regime of a few electrons in uncapped InAs quantum dots by tunneling spectroscopy and wave function (WF) mapping at high tunneling currents where electron-electron interactions become relevant. Four clearly resolved ... More
Non-collinear spin states in bottom-up fabricated atomic chainsOct 10 2017Jan 23 2018Non-collinear spin states with unique rotational sense, such as chiral spin-spirals, are recently heavily investigated because of advantages for future applications in spintronics and information technology and as potential hosts for Majorana Fermions ... More
Stabilizing spin systems via symmetrically tailored RKKY interactionsNov 07 2018The spin of a single atom adsorbed on a substrate is a promising building block for future spintronics and quantum computation schemes. To process spin information and also for increased magnetic stability, these building blocks have to be coupled. For ... More
Magnetism and in-gap states of 3d transition metal atoms on superconducting ReMar 25 2019Magnetic atoms on heavy-element superconducting substrates are potential building blocks for realizing topological superconductivity in one- and two-dimensional atomic arrays. Their localized magnetic moments induce so-called Yu-Shiba-Rusinov (YSR) states ... More
Nano-scale magnetic skyrmions and target states in confined geometriesJan 21 2019May 17 2019Research on magnetic systems with broken inversion symmetry has been stimulated by the experimental proof of particle-like configurations known as skyrmions, whose non-trivial topological properties make them ideal candidates for spintronic technology. ... More
Spin spirals in ultra-thin films driven by frustration of exchange interactions: Rh/Fe/Ir(111)Oct 25 2016Numerous complex non-collinear spin structures such as spin spirals and skyrmions have been observed recently in ultrathin transition-metal films at surfaces. In these systems the interfacial Dzyaloshinskii-Moriya interaction (DMI) plays a decisive role ... More
Enhanced spin ordering temperature in ultrathin FeTe films grown on a topological insulatorNov 28 2017Nov 30 2017We studied the temperature dependence of the diagonal double-stripe spin order in one and two unit cell thick layers of FeTe grown on the topological insulator Bi_2Te_3 via spin-polarized scanning tunneling microscopy. The spin order persists up to temperatures ... More
Reconstructions and faceting of H-covered Al(111)Jul 14 1996Jul 19 1996First principles calculations show that H overlayers induce a honeycomb vacancy reconstruction on Al(111). Above one ML H coverage, Al(111) facets into surfaces vicinal to (111), with {100} faceted single and double steps and vacancies on the {111} terraces. ... More
The ultrarelativistic Reissner-Nordstrom field in the Colombeau algebraJun 19 1996Feb 24 1997The electromagnetic field of the ultrarelativistic Reissner-Nordstrom solution shows the physically highly unsatisfactory property of a vanishing field tensor but a nonzero, i.e., delta-like, energy density. The aim of this work is to analyze this situation ... More
Nuclear Astrophysics with Gamma-ray-ray Line ObservationsSep 15 2006Gamma-ray spectrometers with high spectral resolution have been operated in space since 2002. Major efforts to understand instrumental response and backgrounds are a requird before detailed science interpretations can be derived; by now, high-resolution ... More
Gamma-Ray Line AstronomySep 28 2004Gamma-ray lines from radioactive isotopes, ejected into interstellar space by cosmic nucleosynthesis events, are observed with new space telescopes. The Compton Observatory had provided a sky survey for the isotopes 56Co, 22Na, 44Ti, and 26Al, detecting ... More
Cones of ball-ball separable elementsMar 24 2005Let B_1,B_2 be balls in finite-dimensional real vector spaces E_1,E_2, centered around unit length vectors v_1,v_2 and not containing zero. An element in the tensor product space E_1 \otimes E_2 is called B_1 \otimes B_2-separable if it is contained in ... More
Decoherence : An irreversible ProcessJun 01 2001A wide-ranging theory of decoherence is derived from the quantum theory of irreversible processes, with specific results having for their main limitation the assumption of an exact pointer basis.
Heavy-Ion Physics at the LHC with the Compact Muon Solenoid DetectorMay 18 2004Hadron collisions at the LHC offer a unique opportunity to study strong interactions. The exciting data collected by the four RHIC experiments suggest that in heavy-ion collisions at sqrt(s_NN) = 200 GeV, an equilibrated, strongly-coupled partonic system ... More
Almost sure asymptotics for the maximum local time in Brownian environmentMar 02 2010Jun 15 2011We study the asymptotic behaviour of the maximum local time L*(t) of the Brox's process, the diffusion in Brownian environment. Shi proved that the maximum speed of L*(t) is surprisingly, at least t log(log(log t)) whereas in the discrete case it is t. ... More
Scheme of a Derivation of Collapse from Quantum Dynamics IINov 21 2016Is wave function collapse a prediction of the Schr\"odinger equation? This unusual problem is explored in an enlarged framework of interpretation, where quantum dynamics is considered exact and its interpretation is extended to include local entanglement ... More
Sur le groupe d'interpolationSep 26 2006Oct 30 2006We study the interpolation group whose elements are suitable pairs of formal power series. This group has a faithful representation into infinite lower triangular matrices and carries thus a natural structure as a Lie group. The matrix exponential between ... More
An explicit André-Oort type result for P^1(C) x G_m(C)Mar 10 2014Using class field theory we prove an explicit result of Andr\'e-Oort type for $\mathbb{P}^1(\mathbb{C}) \times \mathbb{G}_m(\mathbb{C})$. In this variation the special points of $\mathbb{P}^1(\mathbb{C})$ are the singular moduli, while the special points ... More
Quantization of time-like energy for wave maps into spheresJan 27 2016May 08 2016In this article we consider large energy wave maps in dimension 2+1, as in the resolution of the threshold conjecture by Sterbenz and Tataru, but more specifically into the unit Euclidean sphere, and study further the dynamics of the sequence of wave ... More
Convergence of metric two-level measure spacesMay 02 2018Jun 14 2018In this article we extend the notion of metric measure spaces to so-called metric two-level measure spaces (m2m spaces): An m2m space $(X, r, \nu)$ is a Polish metric space $(X, r)$ equipped with a two-level measure $\nu \in \mathcal{M}_f(\mathcal{M}_f(X))$, ... More
Paperfolding and Catalan numbersJun 17 2004We reprove a few results concerning paperfolding sequences using properties of Catalan numbers modulo 2.
Développements limités et la transformée inverseMar 18 2003The generating series associated to a certain sequence of limited Taylor expansions coincides with the continuously iterated Invert Transform and displays thus a nice functional equality.
Le cocycle du vergerDec 03 2003We define and prove uniqueness of a natural homomorphism (called the Orchard morphism) from some groups associated naturally to a finite set $E$ to the group ${\mathcal E}(E)$ of two-partitions of $E$ representing equivalence relations having at most ... More
Application of Multihomogeneous Covariants to the Essential Dimension of Finite GroupsNov 24 2008We investigate essential dimension of finite groups over arbitrary fields and give a systematic treatment of multihomogenization, introduced by H.Kraft, G.Schwarz and the author. We generalize the central extension theorem of Buhler and Reichstein and ... More
Nonlinear stability of self-similar solutions for semilinear wave equationsNov 12 2008Dec 08 2009We prove nonlinear stability of the fundamental self--similar solution of the wave equation with a focusing power nonlinearity $\psi_{tt}-\Delta \psi=\psi^p$ for $p=3,5,7,...$ in the radial case. The proof is based on a semigroup formulation of the wave ... More
Categorical crepant resolutions for quotient singularitiesJun 17 2014Jun 19 2014We discuss some "folklore" results on categorical crepant resolutions for varieties with quotient singularities.
Stability preservation in Galerkin-type projection-based model order reductionNov 08 2017We consider linear dynamical systems consisting of ordinary differential equations with high dimensionality. The aim of model order reduction is to construct an approximating system of a much lower dimension. Therein, the reduced system may be unstable, ... More
Universal convex coveringsDec 18 2008Jul 01 2009In every dimension $d\ge1$, we establish the existence of a constant $v_d>0$ and of a subset $\mathcal U_d$ of $\mathbb R^d$ such that the following holds: $\mathcal C+\mathcal U_d=\mathbb R^d$ for every convex set $\mathcal C\subset \mathbb R^d$ of volume ... More
Model order reduction and sparse orthogonal expansions for random linear dynamical systemsMay 23 2016We consider linear dynamical systems of ordinary differential equations or differential algebraic equations. Physical parameters are substituted by random variables for an uncertainty quantification. We expand the state variables as well as a quantity ... More
Stability-preserving model order reduction for linear stochastic Galerkin systemsMay 03 2019Mathematical modeling often yields linear dynamical systems in science and engineering. We change physical parameters of the system into random variables to perform an uncertainty quantification. The stochastic Galerkin method yields a larger linear dynamical ... More
Copositive matrices with circulant zero support setMar 16 2016Nov 08 2016Let $n \geq 5$ and let $u^1,\dots,u^n$ be nonnegative real $n$-vectors such that the indices of their positive elements form the sets $\{1,2,\dots,n-2\},\{2,3,\dots,n-1\},\dots,\{n,1,\dots,n-3\}$, respectively. Here each index set is obtained from the ... More
The Hilbert's class field and the p-class group of the cyclotomic fieldsJan 23 2011Jan 27 2011Let $p$ be an irregular prime and $K=\Q(\zeta)$ the $p$-cyclotomic field. Let $\sigma$ be a $\Q$-isomorphism of $K$ generating $Gal(K/\Q)$. Let $S/K$ be a cyclic unramified extension of degree $p$, defined by $S= K(A^{1/p})$ where $A\in K\backslash K^p$, ... More
Some congruences on prime factors of class number of finite algebraic extensions K/QApr 25 2003This paper is a contribution to the description of some congruences on the odd prime factors of the class number of the number fields. An example of results obtained is: Let L/Q be a finite Galois solvable extension with [L:Q]=N, where N > 1 is odd. Let ... More
Correction of systematic errors in scanning tunnelling spectra on semiconductor surfaces: the energy gap of Si(111)-7x7 at 0.3 KAug 19 2009The investigation of the electronic properties of semiconductor surfaces using scanning tunnelling spectroscopy (STS) is often hindered by non-equilibrium transport of the injected charge carriers. We propose a correction method for the resulting systematic ... More
Non-equilibrium finite temperature dynamics of magnetic quantum systems: Applications to spin-polarized scanning tunneling microscopyAug 13 2013We calculate the real time non-equilibrium dynamics of quantum spin systems at finite temperatures. The mathematical framework originates from the $C^*$-approach to quantum statistical mechanics and is applied to samples investigated by means of spin-polarized ... More
The Quantum Theory of Gravitation: I Quantization of Free Fields - II Proof of RenormalizabilityMay 17 2019Quantization of Free Fields: The non-interacting field belonging to a new {\bf SO(1,3)\/} gauge field theory equivalent to General Relativity is canonically quantized in the Lorentz gauge and the physical Fock space for free gauge particles is constructed. ... More
On the two-loop contributions to the pion massJul 16 2007Sep 20 2007We derive a simplified representation for the pion mass to two loops in three-flavour chiral perturbation theory. For this purpose, we first determine the reduced expressions for the tensorial two-loop 2-point sunset integrals arising in chiral perturbation ... More
Anomalies and WZW-term of two-flavour QCDNov 29 2000The U(2)_R x U(2)_L symmetry of QCD with two massless flavours is subject to anomalies which affect correlation functions involving the singlet currents A^0_\mu or V^0_\mu. These are relevant for pion-photon interactions, because - for two flavours - ... More
Theory of the hourglass dispersion of magnetic excitations in high-T$_c$ cupratesOct 27 2008A theory for the dispersion of collective magnetic excitations in superconducting cuprates is presented with the aim to cover both high and low doping regimes. Besides of spin fluctuations describable in the random phase approximation (RPA) we allow for ... More
Measuring 26Al and 60Fe in the GalaxyMar 24 2006With the SPI high-resolution spectrometer on INTEGRAL, new results have been obtained for long-lived radioactive 26Al and 60Fe in our Galaxy: 26Al sources apparently share the pattern of Galactic rotation in the inner Galaxy, and thus allow to estimate ... More
HH135/HH136 - a luminous H$_2$ outflow towards a high-mass protostarJun 20 2006Near-infrared observations towards the luminous IRAS source IRAS11101-5928 and the associated Herbig-Haro objects HH135/HH136 are presented. The observations reveal the presence of a well-collimated, parsec-sized H$_2$ outflow with a total H$_2$ luminosity ... More
Entangled states close to the maximally mixed stateFeb 05 2007Feb 23 2007We give improved upper bounds on the radius of the largest ball of separable states of an m-qubit system around the maximally mixed state. The ratio between the upper bound and the best known lower bound (Hildebrand, quant.ph/0601201) thus shrinks to ... More
Semidefinite descriptions of separable matrix conesJan 20 2007Let K, K' be convex cones residing in finite-dimensional real vector spaces E, E'. An element in the tensor product E \otimes E' is K \otimes K'-separable if it can be represented as finite sum \sum_l x_l \otimes x'_l with x_l \in K and x_l' \in K' for ... More
Charged hadron transverse momentum distributions in Au+Au collisions at sqrt(s_NN) = 200 GeVDec 04 2002We present transverse momentum distributions of charged hadrons produced in Au+Au collisions at sqrt(s_NN) = 200 GeV. The evolution of the spectra for transverse momenta p_T from 0.25 to 5GeV/c is studied as a function of collision centrality over a range ... More
Structure and mobility of cyclohexane as a solvent for Trans-PolyisopreneMar 07 2002Solutions of {\it trans}$-$polyisoprene in cyclohexane are investigated in atomistic detail at different compositions at two different temperatures. We investigate the influence of polymer concentration on the dynamics of the solvent molecules and the ... More
Non-magnetic impurity scattering in a $d_{x^2 - y^2}$ superconductor near a van Hove point: Zn versus Ni in the cupratesDec 13 1995Dec 15 1995We consider the effect of non-magnetic impurities in a $d_{x^2 - y^2}$ superconductor with $\ef$ close to a van Hove singularity. It is shown that the non-trivial density of states (DOS) allows for resonant scattering already at intermediate potential ... More
Conductivity of CuO$_3$-Chains: Disorder versus Electron-Phonon CouplingDec 14 1993The optical conductivity of the CuO$_3$-chains, a subsystem of the 1-2-3 materials, is dominated by a broad peak in the mid-infrared ($\omega \approx 0.2$eV), and a slowly falling high-frequency tail. The 1D $t$-$J$-model is proposed as the relevant low-energy ... More
The memory effect in impulsive plane waves: comments, corrections, clarificationsNov 27 2018Recently the 'memory effect' has been studied in plane gravitational waves and, in particular, in impulsive plane waves. Based on an analysis of the particle motion (mainly in Baldwin-Jeffery-Rosen coordinates) a 'velocity memory effect' is claimed to ... More
A quantum approach to the uniqueness of RealityFeb 07 2013A brief review is given of the present state of an approach to consistency between basic quantum mechanics and a unique macroscopic reality, with no assumption of branching in the state of the universe. The main new idea consists in the recognition of ... More
Graph immersions with parallel cubic formFeb 06 2013We consider non-degenerate graph immersions in R^(n+1) whose cubic form is parallel with respect to the Levi-Civita connection of the affine metric. There exists a correspondence between such graph immersions and pairs (J,g), where J is an n-dimensional ... More
Recent CMS Results on DiffractionMar 05 2017Recent CMS results on diffraction are presented. These include the measurements of the soft diffractive cross sections, of the forward rapidity gap cross section, of the diffractive dijet cross section, the measurement of a large rapidity gap in W and ... More
An explicit André-Oort type result for P^1(C) x G_m(C) based on logarithmic formsMar 12 2014Using linear forms in logarithms we prove an explicit result of Andr\'e-Oort type for $\mathbb{P}^1(\mathbb{C}) \times \mathbb{G}_m(\mathbb{C})$. In this variation the special points of $\mathbb{P}^1(\mathbb{C}) \times \mathbb{G}_m(\mathbb{C})$ are of ... More
Versal Families of Compact Super Riemann SurfacesMar 03 2011Aug 22 2012We call every complex connected (1,1)-dimensional supermanifold a super Riemann surface and construct versal super families of compact ones, where the base spaces are allowed to be certain ringed spaces including all complex supermanifolds. Furthermore ... More
Alignment- and reference-free phylogenomics with colored de-Bruijn graphsMay 10 2019May 15 2019We present a new whole-genome based approach to infer large-scale phylogenies that is alignment- and reference-free. In contrast to other methods, it does not rely on pairwise comparisons to determine distances to infer edges in a tree. Instead, a colored ... More
Nonlinear distributional geometry and general relativityApr 27 2001This work reports on the construction of a nonlinear distributional geometry (in the sense of Colombeau's special setting) and its applications to general relativity with a special focus on the distributional description of impulsive gravitational waves. ... More
A simple method for finite range decomposition of quadratic forms and Gaussian fieldsJun 11 2012May 09 2019We present a simple method to decompose the Green forms corresponding to a large class of interesting symmetric Dirichlet forms into integrals over symmetric positive semi-definite and finite range (properly supported) forms that are smoother than the ... More
Gerasimov's theorem and N-Koszul algebrasJan 22 2008Dec 19 2008The paper is devoted to graded algebras having a single homogeneous relation. Using Gerasimov's theorem, a criterion to be N-Koszul is given, providing new examples. An alternative proof of Gerasimov's theorem for N=2 is given. Some related results on ... More
Wonderful resolutions and categorical crepant resolutions of singularitiesSep 07 2012Sep 03 2013Let $X$ be an algebraic variety with Gorenstein singularities. We define the notion of a wonderful resolution of singularities of $X$ by analogy with the theory of wonderful compactifications of semi-simple linear algebraic groups. We prove that if $X$ ... More
The memory effect in impulsive plane waves: comments, corrections, clarificationsNov 27 2018May 01 2019Recently the 'memory effect' has been studied in plane gravitational waves and, in particular, in impulsive plane waves. Based on an analysis of the particle motion (mainly in Baldwin-Jeffery-Rosen coordinates) a 'velocity memory effect' is claimed to ... More
Frequency domain integrals for stability preservation in Galerkin-type projection-based model order reductionAug 13 2018We investigate linear dynamical systems consisting of ordinary differential equations with high dimensionality. Model order reduction yields alternative systems of much lower dimensions. However, a reduced system may be unstable, although the original ... More
Deeply Virtual Compton Scattering at HERA II (H1 results)May 22 2006New results on the Deeply Virtual Compton Scattering process $\gamma^* p \to \gamma p$ (DVCS) from H1 experiment at the $e p$ collider HERA are presented, using data collected during the year 2004 and corresponding to an integrated luminosity of 39.7 ... More
Old and New Advances in Black Hole Accretion Disk TheoryFeb 15 1999A summary is given of the high-lights during the Reykjavik Midsummer Symposium on Non-Linear Phenomena in Accretion Discs around Black Holes. Such high-lights include the recent advances on understanding: 1) the accretion disc solution branch dominated ... More