Results for "F. Baumberger"

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Control of a two-dimensional electron gas on SrTiO3(111) by atomic oxygenMay 13 2014We report on the formation of a two-dimensional electron gas (2DEG) at the bare surface of (111) oriented SrTiO3. Angle resolved photoemission experiments reveal highly itinerant carriers with a 6-fold symmetric Fermi surface and strongly anisotropic ... More
ARPES Studies of Two-Dimensional Electron Gases at Transition Metal Oxide SurfacesDec 12 2016High mobility two-dimensional electron gases (2DEGs) underpin today's silicon based devices and are of fundamental importance for the emerging field of oxide electronics. Such 2DEGs are usually created by engineering band offsets and charge transfer at ... More
Observation of Large Topologically Trivial Fermi-Arcs in the Candidate Type-II Weyl Semimetal WTe2Apr 08 2016Sep 12 2016We report angle-resolved photoemission experiments resolving the distinct electronic structure of the inequivalent top and bottom (001) surfaces of WTe2. On both surfaces, we identify a surface state that forms a large Fermi-arc emerging out of the bulk ... More
Momentum-resolved lattice dynamics of parent and electron-doped Sr$_{2}$IrO$_{4}$Apr 23 2019The mixing of orbital and spin character in the wavefunctions of the $5d$ iridates has led to predictions of strong couplings between their lattice, electronic and magnetic excitations. As well as realising a novel spin-orbit assisted Mott insulating ... More
Spin-orbit splitting of the Shockley surface state on Cu(111)Jan 25 2013We present angle-resolved photoemission data from Cu(111). Using a focused 6 eV continuous wave laser for photo-excitation, we achieve a high effective momentum resolution enabling the first detection of the Rashba spin splitting in the Shockley surface ... More
Solid Friction from stick-slip to pinning and agingJun 24 2005We review the present state of understanding of solid friction at low velocities and for systems with negligibly small wear effects. We first analyze in detail the behavior of friction at interfaces between wacroscopic hard rough solids, whose main dynamical ... More
Band Structure and Spin-Orbital Texture of the (111)-KTaO3 Two-Dimensional Electron GasMar 14 2019Two-dimensional electron gases (2DEGs) in oxides show great potential for discovering new physical phenomena and at the same time hold promise for electronic applications. In this work we use angle resolved photoemission to determine the electronic structure ... More
Extracting the spectral function of the cuprates by a full two-dimensional analysis: Angle-resolved photoemission spectra of Bi2Sr2CuO6Mar 05 2008Recently, angle-resolved photoemission spectroscopy (ARPES) has revealed a dispersion anomaly at high binding energy near 0.3-0.5eV in various families of the high-temperature superconductors. For further studies of this anomaly we present a new two-dimensional ... More
Fermi arcs and their topological character in the candidate type-II Weyl semimetal MoTe2Apr 27 2016Jul 21 2016We report a combined experimental and theoretical study of the candidate type-II Weyl semimetal MoTe2. Using laser-based angle-resolved photoemission we resolve multiple distinct Fermi arcs on the inequivalent top and bottom (001) surfaces. All surface ... More
Mott transition and collective charge pinning in electron doped Sr2IrO4Jun 18 2018We studied the in-plane dynamic and static charge conductivity of electron doped Sr2IrO4 using optical spectroscopy and DC transport measurements. The optical conductivity indicates that the pristine material is an indirect semiconductor with a direct ... More
Quasiparticle dynamics and spin-orbital texture of the SrTiO3 two-dimensional electron gasMar 03 2014Sep 07 2014Two-dimensional electron gases (2DEGs) in SrTiO$_3$ have become model systems for engineering emergent behaviour in complex transition metal oxides. Understanding the collective interactions that enable this, however, has thus far proved elusive. Here ... More
Controlling bulk conductivity in topological insulators: Key role of anti-site defectsApr 18 2012The binary Bi-chalchogenides, Bi2Ch3, are widely regarded as model examples of a recently discovered new form of quantum matter, the three-dimensional topological insulator (TI) [1-4]. These compounds host a single spin-helical surface state which is ... More
Emergent quantum confinement at topological insulator surfacesJun 04 2012Bismuth-chalchogenides are model examples of three-dimensional topological insulators. Their ideal bulk-truncated surface hosts a single spin-helical surface state, which is the simplest possible surface electronic structure allowed by their non-trivial ... More
Strong electron correlations in the normal state of FeSe0.42Te0.58Dec 16 2009Feb 10 2010We investigate the normal state of the '11' iron-based superconductor FeSe0.42Te0.58 by angle resolved photoemission. Our data reveal a highly renormalized quasiparticle dispersion characteristic of a strongly correlated metal. We find sheet dependent ... More
Creation and control of a two-dimensional electron liquid at the bare SrTiO3 surfaceOct 05 2010May 08 2011Many-body interactions in transition-metal oxides give rise to a wide range of functional properties, such as high-temperature superconductivity, colossal magnetoresistance, or multiferroicity. The seminal recent discovery of a two-dimensional electron ... More
Coupling Of The B1g Phonon To The Anti-Nodal Electronic States of Bi2Sr2Ca0.92Y0.08Cu2O(8+delta)Mar 19 2004Jun 23 2004Angle-resolved photoemission spectroscopy (ARPES) on optimally doped Bi2Sr2Ca0.92Y0.08Cu2O(8+delta) uncovers a coupling of the electronic bands to a 40 meV mode in an extended k-space region away from the nodal direction, leading to a new interpretation ... More
Heavy d-Electron Quasiparticle Interference and Real-space Electronic Structure of Sr3Ru2O7Nov 15 2009Nov 17 2009The intriguing idea that strongly interacting electrons can generate spatially inhomogeneous electronic liquid crystalline phases is over a decade old, but these systems still represent an unexplored frontier of condensed matter physics. One reason is ... More
Fermi surface and quasiparticle excitations of Sr$_{2}$RhO$_{4}$Apr 18 2006The electronic structure of the layered 4$d$ transition metal oxide Sr$_{2}$RhO$_{4}$ is investigated by angle resolved photoemission. We find well-defined quasiparticle excitations with a highly anisotropic dispersion, suggesting a quasi-two-dimensional ... More
Anisotropic exchange and spin-wave damping in pure and electron-doped Sr$_2$IrO$_4$Mar 27 2017Aug 31 2017The collective magnetic excitations in the spin-orbit Mott insulator (Sr$_{1-x}$La$_x$)$_2$IrO$_4$ ($x=0,\,0.01,\,0.04,\, 0.1$) were investigated by means of resonant inelastic x-ray scattering. We report significant magnon energy gaps at both the crystallographic ... More
Electronic structure of buried LaNiO3 layers in (111)-oriented LaNiO3/LaMnO3 superlattices probed by soft x-ray ARPESNov 25 2016Taking advantage of the large electron escape depth of soft x-ray angle resolved photoemission spectroscopy we report electronic structure measurements of (111)-oriented [LaNiO3/LaMnO3] superlattices and LaNiO3 epitaxial films. For thin films we observe ... More
Shear response of a frictional interface to a normal load modulationMay 29 2000We study the shear response of a sliding multicontact interface submitted to a harmonically modulated normal load, without loss of contact. We measure, at low velocities ($V<100 \mu$m.s$^{-1}$), the average value $\bar{F}$ of the friction force and the ... More
Frictional dissipation of polymeric solids vs interfacial glass transitionJul 19 2006We present single contact friction experiments between a glassy polymer and smooth silica substrates grafted with alkylsilane layers of different coverage densities and morphologies. This allows us to adjust the polymer/substrate interaction strength. ... More
Non-Amontons behavior of friction in single contactsOct 10 2005We report on the frictional properties of a single contact between a glassy polymer lens and a flat silica substrate covered either by a disordered or by a self-assembled alkylsilane monolayer. We find that, in contrast to common belief, the Amontons ... More
Solvent control of crack dynamics in a reversible hydrogelMay 16 2006The resistance to fracture of reversible biopolymer hydrogels is an important control factor of the cutting/slicing and eating characteristics of food gels. It is also critical for their utilization in tissue engineering, for which mechanical protection ... More
Glass-like dynamics of the strain-induced coil/helix transition on a permanent polymer networkJan 28 2016We study the stress response to a step strain of covalently bonded gelatin gels in the temperature range where triple helix reversible crosslink formation is prohibited. We observe slow stress relaxation towards a $T$-dependent finite asymptotic level. ... More
Crack front échelon instability in mixed mode fracture of a strongly nonlinear elastic solidOct 01 2013Mixed mode (I+III) loading induces segmented crack front \'echelon structures connected by steps. We study this instability in a highly deformable, strain-hardening material. We find that \'echelons develop beyond a finite, size-independent mode mixity ... More
Self healing slip pulses along a gel/glass interfaceOct 19 2001We present an experimental evidence of self-healing shear cracks at a gel/glass interface. This system exhibits two dynamical regimes depending on the driving velocity : steady sliding at high velocity (> Vc = 100-125 \mu m/s), caracterized by a shear-thinning ... More
Fermi surface and van Hove singularities in the itinerant metamagnet Sr3Ru2O7Mar 06 2008Jun 26 2008The low-energy electronic structure of the itinerant metamagnet Sr3Ru2O7 is investigated by angle resolved photoemission and density functional calculations. We find well-defined quasiparticle bands with resolution limited line widths and Fermi velocities ... More
Persistence of antiferromagnetic order upon La substitution in the $4d^4$ Mott insulator Ca$_2$RuO$_4$May 15 2018Jun 28 2018The chemical and magnetic structures of the series of compounds Ca$_{2-x}$La$_x$RuO$_4$ [$x = 0$, $0.05(1)$, $0.07(1)$, $0.12(1)$] have been investigated using neutron diffraction and resonant elastic x-ray scattering. Upon La doping, the low temperature ... More
Angle-resolved photoemission studies of lattice polaron formation in the cuprate Ca2CuO2Cl2Feb 23 2007To elucidate the nature of the single-particle excitations in the undoped parent cuprates, we have performed a detailed study of Ca2CuO2Cl2 using photoemission spectroscopy. The photoemission lineshapes of the lower Hubbard band are found to be well-described ... More
Jamming creep of a frictional interfaceJan 23 2001We measure the displacement response of a frictional multicontact interface between identical polymer glasses to a biased shear force oscillation. We evidence the existence, for maximum forces close below the nominal static threshold, of a jamming creep ... More
Interplay between shear loading and structural aging in a physical gelMay 12 2009We show that the aging of the mechanical relaxation of a gelatin gel exhibits the same scaling phenomenology as polymer and colloidal glasses. Besides, gelatin is known to exhibit logarithmic structural aging (stiffening). We find that stress accelerates ... More
Self-healing slip pulses and the friction of gelatin gelsMar 07 2003We present an extensive experimental study and scaling analysis of friction of gelatin gels on glass. At low driving velocities, sliding occurs via propagation of periodic self-healing slip pulses whose velocity is limited by collective diffusion of the ... More
Fracture of a biopolymer gel as a viscoplastic disentanglement processJul 05 2006We present an extensive experimental study of mode-I, steady, slow crack dynamics in gelatin gels. Taking advantage of the sensitivity of the elastic stiffness to gel composition and history we confirm and extend the model for fracture of physical hydrogels ... More
Elasticity and onset of frictional dissipation at a non-sliding multicontact interfaceOct 15 2002We measure the elastic and dissipative responses of a multicontact interface, formed between the rough surfaces of two contacting macroscopic solids, submitted to a biased oscillating shear force. We evidence that beyond a linear viscoelastic regime, ... More
Rheological aging and rejuvenation in solid friction contactsFeb 14 2002We study the low-velocity (0.1--100 $\mu$m.s$^{-1}$) frictional properties of interfaces between a rough glassy polymers and smooth silanized glass, a configuration which gives direct access to the rheology of the adhesive joints in which shear localizes. ... More
Observation of out-of-plane spin texture in a SrTiO3 (111) two-dimensional electron gasJun 05 2018We explore the second order bilinear magnetoelectric resistance (BMER) effect in the d-electron-based two-dimensional electron gas (2DEG) at the SrTiO3 (111) surface. We find an evidence of a spin-split band structure with the archetypal spin-momentum ... More
In-situ strain-tuning of the metal-insulator-transition of Ca$_{2}$RuO$_{4}$ in angle-resolved photoemission experimentsMar 01 2018Oct 24 2018We report the evolution of the $k$-space electronic structure of lightly doped bulk Ca$_{2}$RuO$_{4}$ with uniaxial strain. Using ultrathin plate-like crystals, we achieve strain levels up to $-4.1\%$, sufficient to suppress the Mott phase and access ... More
Absence of Giant Spin Splitting in the Two-Dimensional Electron Liquid at the Surface of SrTiO$_3$ (001)Mar 01 2016We reinvestigate the putative giant spin splitting at the surface of SrTiO$_3$ reported by Santander-Syro $et~al.$ [Nature Mat. 13, 1085 (2014)]. Our spin- and angle-resolved photoemission experiments on (001) oriented surfaces supporting a two-dimensional ... More
Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin filmsMar 01 2017Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic ... More
Missing Quasiparticles and the Chemical Potential Puzzle in the Doping Evolution of the Cuprate SuperconductorsJun 30 2004Jul 06 2004The evolution of Ca$_{2-x}$Na$_{x}$CuO$_{2}$Cl$_{2}$ from Mott insulator to superconductor was studied using angle-resolved photoemission spectroscopy. By measuring both the excitations near the Fermi energy as well as non-bonding states, we tracked the ... More
Collapse of the Mott gap and emergence of a nodal liquid in lightly doped Sr$_2$IrO$_4$Jun 01 2015Superconductivity in underdoped cuprates emerges from an unusual electronic state characterised by nodal quasiparticles and an antinodal pseudogap. The relation between this state and superconductivity is intensely studied but remains controversial. The ... More
Structural origin of apparent Fermi surface pockets in angle-resolved photoemission of Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+δ}$Dec 07 2010We observe apparent hole pockets in the Fermi surfaces of single-layer Bi-based cuprate superconductors from angle-resolved photoemission (ARPES). From detailed low-energy electron diffraction measurements and an analysis of the ARPES polarization-dependence, ... More
Subband structure of a two-dimensional electron gas formed at the polar surface of the strong spin-orbit perovskite KTaO$_3$Nov 11 2011We demonstrate the formation of a two-dimensional electron gas (2DEG) at the $(100)$ surface of the $5d$ transition-metal oxide KTaO$_3$. From angle-resolved photoemission, we find that quantum confinement lifts the orbital degeneracy of the bulk band ... More
Doping dependence of the coupling of electrons to bosonic modes in the single-layer high-temperature Bi2Sr2CuO6 superconductorFeb 22 2006A recent highlight in the study of high-Tc superconductors is the observation of band renormalization / self-energy effects on the quasiparticles. This is seen in the form of kinks in the quasiparticle dispersions as measured by photoemission and interpreted ... More
Quantitative analysis of Sr2RuO4 ARPES spectra: Many-body interactions in a model Fermi liquidAug 04 2005ARPES spectra hold a wealth of information about the many-body interactions in a correlated material. However, the quantitative analysis of ARPES spectra to extract the various coupling parameters in a consistent manner is extremely challenging, even ... More
Spectroscopic evidence for polaronic behaviour of the strong spin-orbit insulator Sr$_3$Ir$_2$O$_7$Feb 02 2013We investigate the bilayer Ruddlesden-Popper iridate Sr$_3$Ir$_2$O$_7$ by temperature-dependent angle-resolved photoemission. We find a narrow-gap correlated insulator, with spectral features indicative of a polaronic ground state, strikingly similar ... More
A facility for the analysis of the electronic structures of solids and their surfaces by synchrotron radiation photoelectron spectroscopyDec 22 2016A synchrotron radiation beamline in the photon energy range of 18 - 240 eV and an electron spectroscopy end station have been constructed at the 3 GeV Diamond Light Source storage ring. The instrument features a variable polarisation undulator, a high ... More
Microfocus laser-ARPES on encapsulated mono-, bi-, and few-layer 1T'-WTe$_2$Nov 12 2018Two-dimensional crystals of semimetallic van der Waals materials hold much potential for the realization of novel phases, as exemplified by the recent discoveries of a polar metal in few layer 1T'-WTe$_2$ and of a quantum spin Hall state in monolayers ... More
Magic angles and cross-hatching instability in hydrogel fractureJan 10 2008Feb 29 2008The full 2D analysis of roughness profiles of fracture surfaces resulting from quasi-static crack propagation in gelatin gels reveals an original behavior characterized by (i) strong anisotropy with maximum roughness at $V$-independent symmetry-preserving ... More
Two-step build-up of a thermoreversible polymer network: From early local to late collective dynamicsMar 05 2015We probe the mechanisms at work in the build-up of thermoreversible gel networks, with the help of hybrid gelatin gels containing a controlled density of irreversible, covalent crosslinks (CL), which we quench below the physical gelation temperature. ... More
Formation and consequences of heavy d-electron quasiparticles in Sr3Ru2O7Oct 31 2012We report angle-resolved photoelectron spectroscopy measurements of the quantum critical metal Sr3Ru2O7 revealing itinerant Ru 4d-states confined over large parts of the Brillouin zone to an energy range of < 6 meV, nearly three orders of magnitude lower ... More
High-resolution photoemission on Sr2RuO4 reveals correlation-enhanced effective spin-orbit coupling and dominantly local self-energiesDec 16 2018May 07 2019We explore the interplay of electron-electron correlations and spin-orbit coupling in the model Fermi liquid Sr2RuO4 using laser-based angle-resolved photoemission spectroscopy. Our precise measurement of the Fermi surface confirms the importance of spin-orbit ... More
High-resolution photoemission on Sr2RuO4 reveals correlation-enhanced effective spin-orbit coupling and dominantly local self-energiesDec 16 2018We explore the interplay of electron-electron correlations and spin-orbit coupling in the model Fermi liquid Sr2RuO4 using laser-based angle-resolved photoemission spectroscopy. Our precise measurement of the Fermi surface confirms the importance of spin-orbit ... More
Tailoring the nature and strength of electron-phonon interactions in the SrTiO$_3$(001) two-dimensional electron liquidJun 03 2015Feb 19 2016Surfaces and interfaces offer new possibilities for tailoring the many-body interactions that dominate the electrical and thermal properties of transition metal oxides. Here, we use the prototypical two-dimensional electron liquid (2DEL) at the SrTiO$_3$(001) ... More
Large tuneable Rashba spin splitting of a two-dimensional electron gas in Bi2Se3Mar 16 2011Aug 26 2011We report a Rashba spin splitting of a two-dimensional electron gas in the topological insulator Bi$_2$Se$_3$ from angle-resolved photoemission spectroscopy. We further demonstrate its electrostatic control, and show that spin splittings can be achieved ... More
Strong energy-momentum dispersion of phonon-dressed carriers in the lightly doped band insulator SrTiO$_3$Feb 07 2010Much progress has been made recently in the study of the effects of electron-phonon (el-ph) coupling in doped insulators using angle resolved photoemission (ARPES), yielding evidence for the dominant role of el-ph interactions in underdoped cuprates. ... More
Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopyMar 13 2017Jun 27 2017The effective Mott gap measured by scanning tunneling microscopy (STM) in the lightly doped Mott insulator $(\rm{Sr}_{1 -x}\rm{La}_x)_2\rm{IrO}_4$ differs greatly from values reported by photoemission and optical experiments. Here, we show that this is ... More
A weakly correlated Fermi liquid state with a small Fermi surface in lightly doped Sr$_3$Ir$_2$O$_7$Sep 24 2014We characterize the electron doping evolution of (Sr$_{1-x}$La$_x$)$_3$Ir$_2$O$_7$ by means of angle-resolved photoemission. Concomitant with the metal insulator transition around $x\approx0.05$ we find the emergence of coherent quasiparticle states forming ... More
Universality of pseudogap and emergent order in lightly doped Mott insulatorsApr 28 2016Sep 30 2016It is widely believed that high-temperature superconductivity in the cuprates emerges from doped Mott insulators. The physics of the parent state seems deceivingly simple: The hopping of the electrons from site to site is prohibited because their on-site ... More
Depleted Kondo LatticesApr 07 2001Nov 17 2001We consider a two dimensional Kondo lattice model with exchange J and hopping t in which three out of four impurity spins are removed in a regular way. At the particle-hole symmetric point the model may be studied with auxiliary field quantum Monte Carlo ... More
The interplay between d-wave superconductivity and antiferromagnetic fluctuations: a quantum Monte Carlo studyJun 25 1998We consider the repulsive Hubbard model on a square lattice with an additional term, W, which depends upon the square of a single-particle nearest-neighbor hopping. At half-band filling, constant W, we show that enhancing U/t drives the system from a ... More
Superconductors as ideal spin sources for spintronicsNov 05 2007Apr 03 2008Spin-polarized transport is investigated in normal metal-superconductor (NS) junctions as a function of interface transmissivity as well as temperature when the density of states of a superconductor is Zeeman-split in response to an exchange field (h_exc). ... More
Ultra-High-Energy Cosmic Rays from the Radio Lobes of AGNsSep 22 2008In the past year, the HiRes and Auger collaborations have reported the discovery of a high-energy cutoff in the ultra-high energy cosmic-ray (UHECR) spectrum, and an apparent clustering of the highest energy events towards nearby active galactic nuclei ... More
Sampling exactly from the normal distributionMar 25 2013Jun 10 2014An algorithm for sampling exactly from the normal distribution is given. The algorithm reads some number of uniformly distributed random digits in a given base and generates an initial portion of the representation of a normal deviate in the same base. ... More
Transverse Mercator with an accuracy of a few nanometersFeb 08 2010Feb 03 2011Implementations of two algorithms for the transverse Mercator projection are described; these achieve accuracies close to machine precision. One is based on the exact equations of Thompson and Lee and the other uses an extension of Krueger's series for ... More
Quaternions in molecular modelingJun 23 2005Apr 04 2006Quaternions are an important tool to describe the orientation of a molecule. This paper considers the use of quaternions in matching two conformations of a molecule, in interpolating rotations, in performing statistics on orientational data, in the random ... More
Long-Time Correlations in Stochastic SystemsJan 11 2005In recent years, there has been considerable interest in understanding the motion in Hamiltonian systems when phase space is divided into stochastic and integrable regions. This paper studies one aspect of this problem, namely, the motion of trajectories ... More
Exchange Monte Carlo for Molecular Simulations with Monoelectronic HamiltoniansMar 04 2002We introduce a general Monte Carlo scheme for achieving atomistic simulations with monoelectronic Hamiltonians including the thermalization of both nuclear and electronic degrees of freedom. The kinetic Monte Carlo algorithm is used to obtain the exact ... More
PINGSoft 2: an IDL Integral Field Spectroscopy Software, ready for the CALIFA survey dataNov 01 2012PINGSoft, is a set of IDL routines designed to visualise, manipulate, and analyse integral field spectroscopy (IFS) data regardless of the original instrument and spaxel shape. PINGSoft 2 is a relatively major upgrade with respect to the first version: ... More
Contraction Elimination in Sequent Based Ground Equational CalculusDec 30 2015In "Cut Elimination for Gentzen's Sequent Calculus with Equality and Logic of Partial Terms" LNCS 7750,161-172(2013), we have shown that the cut rule is eliminable in two ground equational sequent calculi, to be denoted by EQ_M and EQ'. In this note we ... More
Probing the unitarity of the renormalizable theory of massive conformal gravityJul 27 2017Apr 03 2018The presence of an unstable massive spin-2 ghost state in the renormalizable theory of massive conformal gravity leads to a pair of complex poles appearing in the first sheet of the energy plane. Here we show that the positions of these poles are gauge ... More
Reply to "Comment on 'Quantum massive conformal gravity' by F. F. Faria"Aug 03 2016Jan 07 2017Recently in (Eur. Phys. J. C 76:341, 2016) [arXiv:1604.08706], Myung has suggested that the renormalizability of massive conformal gravity is meaningless unless the massive ghost states of the theory are stable. Here we show that massive conformal gravity ... More
Cosmology in massive conformal gravityOct 19 2014Mar 06 2019In this paper we find the cosmological solutions of the massive conformal gravity field equations in the presence of matter fields. In particular, we show that the solution of negative curvature is in good agreement with our universe.
Computation of Green's functions through algebraic decomposition of operatorsJul 04 2017In this article we use linear algebra to improve the computational time for the obtaining of Green's functions of linear differential equations with reflection (DER). This is achieved by decomposing both the `reduced' equation (the ODE associated to a ... More
Comment on the relation between the collinear tripartition and the collective model of the atomic nucleiApr 08 2019It is shown that the collinear tripartition in the case of spontaneous fission of 252Cf generically follows the principles of the collective Bohr's model. Qualitative consideration is supported by the numerical trajectory calculations.
Universality of pseudogap and emergent order in lightly doped Mott insulatorsApr 28 2016It is widely believed that high-temperature superconductivity in the cuprates emerges from doped Mott insulators. The physics of the parent state seems deceivingly simple: The hopping of the electrons from site to site is prohibited because their on-site ... More
Quantum Monte Carlo simulations of the half-filled two-dimensional Kondo lattice modelApr 13 1999The 2D half-filled Kondo lattice model with exchange J and nearest neighbor hopping t is considered. It is shown that this model belongs to a class of Hamiltonians for which zero-temperature auxiliary field Monte Carlo methods may be efficiently applied. ... More
A Self-Organizing Neural Scheme for Door Detection in Different EnvironmentsJan 03 2013Doors are important landmarks for indoor mobile robot navigation and also assist blind people to independently access unfamiliar buildings. Most existing algorithms of door detection are limited to work for familiar environments because of restricted ... More
Geodesics on an ellipsoid of revolutionFeb 07 2011Algorithms for the computation of the forward and inverse geodesic problems for an ellipsoid of revolution are derived. These are accurate to better than 15 nm when applied to the terrestrial ellipsoids. The solutions of other problems involving geodesics ... More
Stochastic Ion Heating by a Lower Hybrid Wave: IIJan 07 2005The motion of an ion in a coherent lower hybrid wave (characterized by |k_parallel| << |k_perp| and omega >> Omega_i) in a tokamak plasma is studied. For ions satisfying v_perp > omega/k_perp, the Lorentz force law for the ions is reduced to a set of ... More
Right-left asymmetry of radiation from fission induced by polarised neutronsFeb 09 2009The effect of the right-left asymmetry is considered in the angular distribution of gamma quanta from fission of U-235 by polarised thermal neutrons, which depends on the polarisation of the neutrons with respect to the gamma-fission plane. Electric dipole ... More
Angula distanco en kalotoDec 02 2003A cap in a 2-D sphere is considered, smaller than an hemisphere. Two points are randomly chosen in the cap. The probability density that the angular separation between the points have a given value is obtained. The knowledge of this function is important ... More
Movoj sub newtona logaritma potencialoOct 16 2003A linear density of mass is assumed uniformly distributed along an infinitely long straight line. All possible motions of a test particle are described, under the newtonian logarithmic gravitational potential alone. Those most interesting occur in planes ... More
The index of isolated umbilics on surfaces of non-positive curvatureApr 09 2014It is shown that if a $C^2$ surface $M\subset\mathbb R^3$ has negative curvature on the complement of a point $q\in M$, then the $\mathbb Z/2$-valued Poincar\'e-Hopf index at $q$ of either distribution of principal directions on $M-\{q\}$ is non-positive. ... More
The Study of Nebular Emission on Nearby Spiral Galaxies in the IFU EraNov 14 2013A new generation of wide-field emission-line surveys based on integral field units (IFU) is allowing us to obtain spatially resolved information of the gas-phase emission in nearby late-type galaxies, based on large samples of HII regions and full two-dimensional ... More
A hyperbolic version of the phasor addition formulaNov 20 2014In this article we review the basics of the phasor formalism in a rigorous way, highlighting the physical motivation behind it and presenting a hyperbolic counterpart of the phasor addition formula.
On the vDVZ discontinuity in massive conformal gravityMar 03 2017Mar 05 2019By taking the massless limit of linearized massive conformal gravity coupled to a source, we show that the theory is free from the vDVZ discontinuity. This result is confirmed when we take the massless limit of the gravitational potential of the theory, ... More
Collinear true ternary fission as the consequence of the collective nuclear modelApr 24 2019May 05 2019The concept of collinear spontaneous true ternary fission of 252Cf is subject to critical analysis. The conclusion is that the collinear flight of the fragments turns out to be a natural and most probable mode. The collinearity arises in the model on ... More
On the mixing time of the 2D stochastic Ising model with "plus" boundary conditions at low temperatureMay 19 2009Sep 15 2009We consider the Glauber dynamics for the 2D Ising model in a box of side L, at inverse temperature $\beta$ and random boundary conditions $\tau$ whose distribution P either stochastically dominates the extremal plus phase (hence the quotation marks in ... More
Fokker-Planck and Quasilinear CodesJan 13 2005The interaction of radio-frequency waves with a plasma is described by a Fokker-Planck equation with an added quasilinear term. Methods for solving this equation on a computer are discussed.
Numerical Techniques for the Study of Long-Time CorrelationsJan 26 2004In the study of long-time correlations extremely long orbits must be calculated. This may be accomplished much more reliably using fixed-point arithmetic. Use of this arithmetic on the Cray-1 computer is illustrated.
Phase diagram of the half-filled two-dimensional SU(N) Hubbard-Heisenberg model: a quantum Monte Carlo studyJun 03 2004We investigate the phase diagram of the half-filled SU(N) Hubbard-Heisenberg model with hopping t, exchange J and Hubbard U, on a square lattice. In the large-N limit, and as a function of decreasing values of t/J, the model shows a transition from a ... More
Coherence scale of the two-dimensional Kondo Lattice modelJan 07 2004A doped hole in the two-dimensional half-filled Kondo lattice model with exchange J and hopping t has momentum (pi,pi) irrespective of the coupling J/t. The quasiparticle residue of the doped hole, Z_{(\pi, \pi)}, tracks the Kondo scale, T_K, of the corresponding ... More
UHECRs from the Radio Lobes of AGNsSep 23 2008Oct 07 2008We report a stochastic mechanism of particle acceleration from first principles in an environment having properties like those of Radio Lobes in AGNs. We show that energies $\sim 10^{20}$ eV are reached in $\sim 10^6$ years for protons. Our results reopen ... More
Taub, Rindler, and the static plateFeb 03 2005An infinite 3D plate of homogeneous incompressible fluid is considered, with finite thickness, together with a 2D infinite homogeneous mass in its centre. Einstein equations are exactly solved, in the interior of the 3D mass. The solution is joined to ... More
Separations inside a cubeDec 28 2001Two points are randomly selected inside a three-dimensional euclidian cube. The value l of their separation lies somewhere between zero and the length of a diagonal of the cube. The probability density P(l) of the separation is obtained analytically. ... More
Cosmic crystallography in a circleMay 15 2000Oct 05 2000In a circle (an S^1) with circumference 1 assume m objects distributed pseudo-randomly. In the universal covering R^1 assume the objects replicated accordingly, and take an interval L>1. In this interval, make the normalized histogram of the pair separations ... More
Synchronization of non-chaotic dynamical systemsAug 09 1999Dec 14 2000A synchronization mechanism driven by annealed noise is studied for two replicas of a coupled-map lattice which exhibits stable chaos (SC), i.e. irregular behavior despite a negative Lyapunov spectrum. We show that the observed synchronization transition, ... More