Results for "F. Baumberger"

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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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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 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
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
Two- and three- dimensional few-body systems in the universal regimeNov 11 2014Macro properties of cold atomic gases are driven by few-body correlations, even if the gas has thousands of particles. Quantum systems composed of two and three particles with attractive zero\=/range pairwise interactions are considered for general masses ... More
SU(2)-spin Invariant Auxiliary Field Quantum Monte Carlo Algorithm for Hubbard modelsJun 25 1998Auxiliary field quantum Monte Carlo methods for Hubbard models are generally based on a Hubbard-Stratonovitch transformation where the field couples to the z-component of the spin. This transformation breaks SU(2) spin invariance. The symmetry is restored ... More
Adiabatic Magnetization of Superconductors as a High-Performance Cooling MechanismNov 25 2008The adiabatic magnetization of a superconductor is a cooling principle proposed in the 30s, which has never been exploited up to now. Here we present a detailed dynamic description of the effect, computing the achievable final temperatures as well as ... More
Hybrid superconducting quantum magnetometerMar 18 2011Dec 03 2011A superconducting quantum magnetometer based on magnetic flux-driven modulation of the density of states of a proximized metallic nanowire is theoretically analyzed. With optimized geometrical and material parameters transfer functions up to a few mV/Phi_0 ... More
Long-Time Correlations in the Stochastic RegimeJan 11 2005The phase space for Hamiltonians of two degrees of freedom is usually divided into stochastic and integrable components. Even when well into the stochastic regime, integrable orbits may surround small stable regions or islands. The effect of these islands ... More
Temporal Evolution of Lower Hybrid Waves in the Presence of Ponderomotive Density FluctuationsJan 10 2005The propagation of lower hybrid waves in the presence of ponderomotive density fluctuations is considered. The problem is treated in two dimensions and, in order to be able to correctly impose the boundary conditions, the waves are allowed to evolve in ... More
Algorithms for geodesicsSep 21 2011Mar 28 2012Algorithms for the computation of geodesics on an ellipsoid of revolution are given. These provide accurate, robust, and fast solutions to the direct and inverse geodesic problems and they allow differential and integral properties of geodesics to be ... More
Stochastic Optimal Control with Delay in the Control I: solving the HJB equation through partial smoothingJul 21 2016Stochastic optimal control problems governed by delay equations with delay in the control are usually more difficult to study than the the ones when the delay appears only in the state. This is particularly true when we look at the associated Hamilton-Jacobi-Bellman ... More
Experimentally obtaining metrics in general relativityMay 10 2005It seems to be not well known that the metrics of general relativity (GR) can be obtained without integrating Einstein equations. To that, we need only define a unit for GR-interval $\Delta s$, and observe 10 geodesics (out of which at least one must ... More
Right-Left Asymmetry of Radiation from FissionOct 09 2007The effect of the right-left asymmetry is considered in the predicted earlier electric dipole radiation from fission fragments arising due to the Strutinski-Denisov induced polarisation mechanism. The magnitude of the asymmetry parameter is on the level ... More
Gas accretion on spiral galaxies: bar formation and renewalJun 17 2002The effects of gas accretion on spiral disk dynamics and stability are studied through N-body simulations, including star formation and gas/stars mass exchange. The detailed processes of bar formation, bar destruction and bar re-formation are followed, ... More
Formation of polar ring galaxiesJan 20 2003Feb 04 2003Polar ring galaxies are peculiar systems in which a gas rich, nearly polar ring surrounds an early-type or elliptical host galaxy. Two formation scenarios for these objects have been proposed: they are thought to form either in major galaxy mergers or ... More
A new geometrical approach to metric-affine gravityJul 16 2013Here we consider a metric-affine theory of gravity in which the gravitational Lagrangian is the scalar curvature. The matter action is allowed to depend also on the torsion and the nonmetricity, which are considered as the field variables together with ... More
Cosmology in massive conformal gravityOct 19 2014Sep 25 2015In this article 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 spatial curvature is in good agreement with our universe.
FCNC production of same sign Top quark pairs at the LHCNov 05 2003Nov 06 2003We study the possibility of same sign top quark pair production at the LHC (and the VLHC) as a direct probe of FCNC processes. Besides the SM neutral Z boson, two other neutral bosons are considered, a top-Higgs type scalar and a Z' boson that appear ... 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
tbW vertex in the Littlest Higgs Model with T-parityOct 27 2008Feb 12 2009A study of the effective tbW vertex is done in the littlest Higgs model with T parity that includes the one loop induced weak dipole coefficient f_{2R}. The top's width, the W-boson helicity in the t-> bW^+ decay as well as the t-channel and the s-channel ... More
Non-Statistical gamma Rays from FragmentsOct 09 2007Polarization mechanism by Strutinsky-Denisov gives rise to the electric dipole radiation from fragments. Its probability calculated within the LDM turns out to be ~3.5x10-2 per fission. The radiation occurs during thermolization of the post-rupture deformation ... More
Measurement of wave-particle interaction and metastable lifetime using laser-induced fluorescenceFeb 27 2019Extensive information, such as ion temperature and wave-particle interactions, can be obtained by direct measurement of ion distribution functions using laser-induced fluorescence (LIF). This nonintrusive plasma diagnostic provides an important window ... 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
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
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
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
Model pseudofermionic systems: connections with exceptional pointsFeb 25 2014We discuss the role of pseudo-fermions in the analysis of some two-dimensional models, recently introduced in connection with non self-adjoint hamiltonians. Among other aspects, we discuss the appearance of exceptional points in connection with the validity ... More