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  • 501. Sundkvist, David
    et al.
    Retinò, Alessandro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Bale, S.
    Dissipation in turbulent plasma due to reconnection in thin current sheets2007Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, nr 2, s. 025004-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present in situ measurements in a space plasma showing that thin current sheets the size of an ion inertial length exist and are abundant in strong and intermittent plasma turbulence. Many of these current sheets exhibit the microphysical signatures of reconnection. The spatial scale where intermittency occurs corresponds to the observed structures. The reconnecting current sheets represent a type of dissipation mechanism, with observed dissipation rates comparable to or even dominating over collisionless damping rates of waves at ion inertial length scales ( X 100), and can have far reaching implications for small-scale dissipation in all turbulent plasmas.

  • 502.
    Szilva, Attila
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Costa, Marcio Jorge Teles da
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Bergman, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Szunyogh, L.
    Nordström, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Interatomic Exchange Interactions for Finite-Temperature Magnetism and Nonequilibrium Spin Dynamics2013Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 111, nr 12, s. 127204-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We derive ab inito exchange parameters for general noncollinear magnetic configurations, in terms of a multiple scattering formalism. We show that the general exchange formula has an anisotropiclike term even in the absence of spin-orbit coupling, and that this term is large, for instance, for collinear configuration in bcc Fe, whereas for fcc Ni it is quite small. We demonstrate that keeping this term leads to what one should consider a biquadratic effective spin Hamiltonian even in the case of collinear arrangement. In noncollinear systems this term results in new tensor elements that are important for exchange interactions at finite temperatures, but they have less importance at low temperature. To illustrate our results in practice, we calculate for bcc Fe magnon spectra obtained from configuration-dependent exchange parameters, where the configurations are determined by finite-temperature effects. Our theory results in the same quantitative results as the finite-temperature neutron scattering experiments.

  • 503.
    Såthe, Conny
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Ström, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Agåker, Marcus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik II.
    Söderström, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Rubensson, Jan-Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Richter, Robert
    Alagia, Michele
    Stranges, Stefano
    Gorczyca, Thomas
    Robicheaux, Francis
    Double Excitations of Helium in Weak Static Electric Fields2006Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 96, s. 043002-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dramatic electric field dependence has been observed in the fluorescence yield spectrum of the doubly excited states in helium, where a rich phenomenology is encountered below the N=2 threshold. Fluorescence yields of certain states can be tuned to zero, while other dipole-forbidden states are significantly enhanced, for fields much weaker than 1  kV/cm. Using an R-matrix multichannel quantum defect theory, spherical-to-parabolic frame transformation method, we are able to reproduce the main features of the observed spectrum, and we discuss the qualitative behavior in terms of weak electric field mixing.

  • 504.
    Söderström, Johan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Mårtensson, Nils
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Travnikova, O.
    Patanen, M.
    Miron, C.
    Saethre, L. J.
    Borve, K. J.
    Rehr, J. J.
    Kas, J. J.
    Vila, F. D.
    Thomas, T. D.
    Svensson, Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Nonstoichiometric Intensities in Core Photoelectron Spectroscopy2012Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 108, nr 19, s. 193005-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    X-ray photoemission spectroscopy is used in a great variety of research fields; one observable is the sample's stoichiometry. The stoichiometry can be deduced based on the expectation that the ionization cross sections for innershell orbitals are independent of the molecular composition. Here we used chlorine-substituted ethanes in the gas phase to investigate the apparent carbon stoichiometry. We observe a nonstoichiometric ratio for a wide range of photon energies, the ratio exhibits x-ray-absorption fine structure spectroscopy (EXAFS)-like oscillations and hundreds of eV above the C1s ionization approaches a value far from 1. These effects can be accounted for by considering the scattering of the outgoing photoelectron, which we model by multiple-scattering EXAFS calculations, and by considering the effects of losses due to monopole shakeup and shakeoff and to intramolecular inelastic scattering processes.

  • 505.
    Tamm, A.
    et al.
    Lawrence Livermore Natl Lab, Quantum Simulat Grp, Livermore, CA 94550 USA.
    Caro, M.
    Virginia Polytech Inst & State Univ, Dept Mech Engn, Arlington, VA 22033 USA.
    Caro, A.
    George Washington Univ, Ashburn, VA 20147 USA.
    Samolyuk, G.
    Oak Ridge Natl Lab, Mat Sci & Technol Div, POB 2009, Oak Ridge, TN 37831 USA.
    Klintenberg, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Correa, A. A.
    Lawrence Livermore Natl Lab, Quantum Simulat Grp, Livermore, CA 94550 USA.
    Langevin Dynamics with Spatial Correlations as a Model for Electron-Phonon Coupling2018Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 120, nr 18, artikkel-id 185501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stochastic Langevin dynamics has been traditionally used as a tool to describe nonequilibrium processes. When utilized in systems with collective modes, traditional Langevin dynamics relaxes all modes indiscriminately, regardless of their wavelength. We propose a generalization of Langevin dynamics that can capture a differential coupling between collective modes and the bath, by introducing spatial correlations in the random forces. This allows modeling the electronic subsystem in a metal as a generalized Langevin bath endowed with a concept of locality, greatly improving the capabilities of the two-temperature model. The specific form proposed here for the spatial correlations produces a physical wave-vector and polarization dependency of the relaxation produced by the electron-phonon coupling in a solid. We show that the resulting model can be used for describing the path to equilibration of ions and electrons and also as a thermostat to sample the equilibrium canonical ensemble. By extension, the family of models presented here can be applied in general to any dense system, solids, alloys, and dense plasmas. As an example, we apply the model to study the nonequilibrium dynamics of an electron-ion two-temperature Ni crystal.

  • 506.
    Tarafder, Kartick
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Kanungo, S.
    Oppeneer, Peter M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Saha-Dasgupta, T.
    Pressure and Temperature Control of Spin-Switchable Metal-Organic Coordination Polymers from Ab Initio Calculations2012Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 109, nr 7, s. 077203-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We explore a combination of density-functional theory with supplemented Coulomb U (DFT + U) and ab initio molecular dynamics simulations to investigate the spin-crossover (SCO) phenomenon in coordination polymers. We demonstrate the applicability of the method for the case of bimetallic metal-organic framework Fe-2[Nb(CN)(8)] center dot (4-pyridinealdoxime)(8) center dot 2H(2)O [see S. Ohkoshi et al. Nat. Chem. 3, 564 (2011)]. Our study shows that this approach is capable of capturing the SCO transitions driven by pressure as well as temperature. In addition to discovering novel spin-state transitions, magnetic states involving changes in the long-range magnetic ordering pattern are achieved, thereby offering the tunability of spin states as well as the long-range order of the spins. We compare the SCO transition in the Fe-based framework with a computer designed Mn-based variant.

  • 507.
    Tardocchi et al., Marco
    et al.
    Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Association, Milan, Italy.
    Conroy, Sean
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Spectral Broadening of Characteristic γ-Ray Emission Peaks from 12C(3He,pγ)14N Reactions in Fusion Plasmas2011Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, s. 205002-Artikkel i tidsskrift (Fagfellevurdert)
  • 508. Tardocchi, M.
    et al.
    Nocente, M.
    Proverbio, I.
    Kiptily, V. G.
    Blanchard, P.
    Conroy, Sean
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Fontanesi, M.
    Grosso, G.
    Kneupner, K.
    Lerche, E.
    Murari, A.
    Cippo, E. Perelli
    Pietropaolo, A.
    Syme, B.
    Van Eester, D.
    Gorini, G.
    Spectral Broadening of Characteristic gamma-Ray Emission Peaks from (12)C((3)He, p gamma)(14)N Reactions in Fusion Plasmas2011Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, nr 20, s. 205002-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The spectral broadening of characteristic gamma-ray emission peaks from the reaction (12)C((3)He, p gamma)(14)N was measured in D((3)He) plasmas of the JET tokamak with ion cyclotron resonance heating tuned to the fundamental harmonic of (3)He. Intensities and detailed spectral shapes of gamma-ray emission peaks were successfully reproduced using a physics model combining the kinetics of the reacting ions with a detailed description of the nuclear reaction differential cross sections for populating the L1-L8 (14)N excitation levels yielding the observed gamma-ray emission. The results provide a paradigm, which leverages knowledge from areas of physics outside traditional plasma physics, for the development of nuclear radiation based methods for understanding and controlling fusion burning plasmas.

  • 509.
    Taroni, Andrea
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Bergman, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Bergqvist, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Hellsvik, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Suppression of Standing Spin Waves in Low-Dimensional Ferromagnets2011Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, nr 3, s. 037202-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We examine the experimental absence of standing spin wave modes in thin magnetic films, by means of atomistic spin dynamics simulations. Using Co on Cu(001) as a model system, we demonstrate that by increasing the number of layers, the optical branches predicted from adiabatic first-principles calculations are strongly suppressed, in agreement with spin-polarized electron energy loss spectroscopy measurements reported in the literature. Our results suggest that a dynamical analysis of the Heisenberg model is sufficient in order to capture the strong damping of the standing modes.

  • 510.
    Thidé, Bo
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Then, H.
    Sjöholm, J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för astronomi och rymdfysik.
    Palmer, K.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för astronomi och rymdfysik.
    Bergman, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Carozzi, T. D.
    Istomin, Ya. N.
    Ibragimov, N. H.
    Khamitova, R.
    Utilization of photon orbital angular momentum in the low-frequency radio domain2007Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, nr 8, s. 087701-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We show numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (less than or similar to 1 GHz), digital techniques can be used to coherently measure the instantaneous, local field vectors and to manipulate them in software. This enables new types of experiments that go beyond what is possible in optics. It allows information-rich radio astronomy and paves the way for novel wireless communication concepts.

  • 511. Thomas, H.
    et al.
    Helal, A.
    Hoffmann, K.
    Kandadai, N.
    Keto, J.
    Andreasson, Jakob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Iwan, Bianca Stella
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Seibert, Marvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Timneanu, Nicusor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Hajdu, Janos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Adolph, M.
    Gorkhover, T.
    Rupp, D.
    Schorb, S.
    Möller, T.
    Doumy, G.
    DiMauro, L. F.
    Hoener, M.
    Murphy, B.
    Berrah, N.
    Messerschmidt, M.
    Bozek, J.
    Bostedt, C.
    Ditmire, T.
    Explosions of Xenon Clusters in Ultraintense Femtosecond X-Ray Pulses from the LCLS Free Electron Laser2012Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 108, nr 13, artikkel-id 133401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Explosions of large Xe clusters (< N > similar to 11 000) irradiated by femtosecond pulses of 850 eV x-ray photons focused to an intensity of up to 1017 W/cm(2) from the Linac Coherent Light Source were investigated experimentally. Measurements of ion charge-state distributions and energy spectra exhibit strong evidence for the formation of a Xe nanoplasma in the intense x-ray pulse. This x-ray produced Xe nanoplasma is accompanied by a three-body recombination and hydrodynamic expansion. These experimental results appear to be consistent with a model in which a spherically exploding nanoplasma is formed inside the Xe cluster and where the plasma temperature is determined by photoionization heating.

  • 512.
    Thunström, Patrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Di Marco, Igor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Electronic entanglement in late transition metal oxides2012Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 109, nr 18, s. 186401-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a study of the entanglement in the electronic structure of the late transition metal monoxides-MnO, FeO, CoO, and NiO-obtained by means of density-functional theory in the local density approximation combined with dynamical mean-field theory. The impurity problem is solved through exact diagonalization, which grants full access to the thermally mixed many-body ground state density operator. The quality of the electronic structure is affirmed through a direct comparison between the calculated electronic excitation spectrum and photoemission experiments. Our treatment allows for a quantitative investigation of the entanglement in the electronic structure. Two main sources of entanglement are explicitly resolved through the use of a fidelity based geometrical entanglement measure, and additional information is gained from a complementary entropic entanglement measure. We show that the interplay of crystal field effects and Coulomb interaction causes the entanglement in CoO to take a particularly intricate form.

  • 513.
    Tian, Li-Yun
    et al.
    Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.;Dalian Univ Technol, Minist Educ, Key Lab Mat Modificat Laser Ion & Electron Beams, Dalian 116024, Peoples R China..
    Levamaki, Henrik
    Univ Turku, Dept Phys & Astron, FI-20014 Turku, Finland.;Turku Univ, Ctr Mat & Surfaces MatSurf, FI-20014 Turku, Finland..
    Ropo, Matti
    Tampere Univ Technol, Dept Phys, FI-33101 Tampere, Finland.;Aalto Univ, Sch Sci, Dept Appl Phys, COMP, POB 11100, FI-00076 Aalto, Finland..
    Kokko, Kalevi
    Univ Turku, Dept Phys & Astron, FI-20014 Turku, Finland.;Turku Univ, Ctr Mat & Surfaces MatSurf, FI-20014 Turku, Finland..
    Nagy, Agnes
    Univ Debrecen, Dept Theoret Phys, H-4010 Debrecen, Hungary..
    Vitos, Levente
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol, Dept Mat Sci & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden.;Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, POB 49, H-1525 Budapest, Hungary..
    Exchange-Correlation Catastrophe in Cu-Au: A Challenge for Semilocal Density Functional Approximations2016Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 117, nr 6, artikkel-id 066401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Semilocal density functional approximations occupy the second rung of the Jacob's ladder model and are thus expected to have certain limits to their applicability. A recent study [Y. Zhang, G. Kresse, and C. Wolverton, Phys. Rev. Lett. 112, 075502 (2014)] hypothesizes that the formation energy, being one of the key quantities in alloy theory, would be beyond the grasp of semilocal density functional theory (DFT). Here, we explore the physics of semilocal DFT formation energies and shed light on the connection between the accuracy of the formation energy and the ability of a semilocal approximation to produce accurate lattice constants. We demonstrate that semilocal functionals designed to perform well for alloy constituents can concomitantly solve the problem of alloy formation energies.

  • 514.
    Tong, D. M.
    et al.
    Dept. of Physics, NUS, Singapore.
    Sjöqvist, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Kwek, L. C.
    Dept. of Physics, NUS, Singapore.
    Oh, C. H.
    Dept. of Physics, NUS, Singapore.
    Erratum: Kinematic Approach to the Mixed State Geometric Phase in Nonunitary Evolution [Phys. Rev. Lett. 93, 080405 (2004)]2005Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, s. 249902-249902Artikkel i tidsskrift (Annet vitenskapelig)
  • 515.
    Tong, D.M.
    et al.
    Dept. of Physics, NUS, Singapore.
    Sjöqvist, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Kwek, L.C.
    Dept. of Physics, NUS, Singapore.
    Oh, C. H.
    Dept. of Physics, NUS, Singapore.
    Kinematic approach to mixed state geometric phase in nonunitary evolution2004Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 93, nr 8, s. 080405-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A kinematic approach to the geometric phase for mixed quantal states in nonunitary evolution is proposed. This phase is manifestly gauge invariant and can be experimentally tested in interferometry. It leads to well-known results when the evolution is unitary.

  • 516.
    Travnikova, O.
    et al.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France..
    Sisourat, N.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Marchenko, T.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France..
    Goldsztejn, G.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Guillemin, R.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France..
    Journel, L.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France..
    Ceolin, D.
    Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France..
    Ismail, I.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Lago, A. F.
    Univ Fed Abc, Ctr Ciencias Nat & Humanas, BR-09210170 Santo Andre, SP, Brazil..
    Puettner, R.
    Free Univ Berlin, Fachbereich Phys, D-14195 Berlin, Germany..
    Piancastelli, Maria Novella
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik. UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.
    Simon, M.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France..
    Subfemtosecond Control of Molecular Fragmentation by Hard X-Ray Photons2017Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 118, nr 21, artikkel-id 213001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tuning hard x-ray excitation energy along Cl 1s -> sigma* resonance in gaseous HCl allows manipulating molecular fragmentation in the course of the induced multistep ultrafast dissociation. The observations are supported by theoretical modeling, which shows a strong interplay between the topology of the potential energy curves, involved in the Auger cascades, and the so-called core-hole clock, which determines the time spent by the system in the very first step. The asymmetric profile of the fragmentation ratios reflects different dynamics of nuclear wave packets dependent on the photon energy.

  • 517.
    Travnikova, Oksana
    et al.
    Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Marchenko, Tatiana
    Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Goldsztejn, Gildas
    Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Jankala, Kari
    Univ Oulu, Ctr Mol Mat Res, POB 3000, Oulu 90014, Finland..
    Sisourat, Nicolas
    Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Carniato, StPhane
    Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Guillemin, Renaud
    Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Journel, Loic
    Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Ceolin, Denis
    Orme Merisiers, Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France..
    Puettner, Ralph
    Free Univ Berlin, Inst Expt Phys, D-14195 Berlin, Germany..
    Iwayama, Hiroshi
    Natl Inst Nat Sci, Inst Mol Sci, UVSOR Facil, 38 Nishigonaka, Okazaki, Aichi 4448585, Japan..
    Shigemasa, Eiji
    Natl Inst Nat Sci, Inst Mol Sci, UVSOR Facil, 38 Nishigonaka, Okazaki, Aichi 4448585, Japan..
    Piancastelli, Maria Novella
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik. Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France..
    Simon, Marc
    Univ Paris 06, Univ Paris 04, CNRS, UMR 7614,Lab Chim Phys Matiere & Rayonnement, F-75005 Paris, France.;Orme Merisiers, Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France..
    Hard-X-Ray-Induced Multistep Ultrafast Dissociation2016Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 116, nr 21, artikkel-id 213001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Creation of deep core holes with very short (tau <= 1 fs) lifetimes triggers a chain of relaxation events leading to extensive nuclear dynamics on a few-femtosecond time scale. Here we demonstrate a general multistep ultrafast dissociation on an example of HCl following Cl 1s -> sigma* excitation. Intermediate states with one or multiple holes in the shallower core electron shells are generated in the course of the decay cascades. The repulsive character and large gradients of the potential energy surfaces of these intermediates enable ultrafast fragmentation after the absorption of a hard x-ray photon.

  • 518. Trines, R.
    et al.
    Bingham, R.
    Dunlop, M. W.
    Vaivads, Andris
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Davies, J. A.
    Mendonca, J. T.
    Silva, L. O.
    Shukla, P. K.
    Spontaneous generation of self-organized solitary wave structures at earth's magnetopause2007Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, nr 20, s. 205006-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spontaneous formation of solitary wave structures has been observed in Earth's magnetopause, and is shown to be caused by the breakup of a zonal flow by the action of drift wave turbulence. Here we show matched observations and modeling of coherent, large-scale solitary electrostatic structures, generated during the interaction of short-scale drift wave turbulence and zonal flows at the Earth's magnetopause. The observations were made by the Cluster spacecraft and the numerical modeling was performed using the wave-kinetic approach to drift wave-zonal flow interactions. Good agreement between observations and simulations has been found, thus explaining the emergence of the observed solitary structures as well as confirming earlier theoretical predictions of their existence.

  • 519.
    Vacher, Morgane
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Teoretisk kemi. Imperial Coll London, Dept Chem, London SW7 2AZ, England..
    Bearpark, Michael J.
    Imperial Coll London, Dept Chem, London SW7 2AZ, England..
    Robb, Michael A.
    Imperial Coll London, Dept Chem, London SW7 2AZ, England..
    Malhado, Joao Pedro
    Imperial Coll London, Dept Chem, London SW7 2AZ, England..
    Electron Dynamics upon Ionization of Polyatomic Molecules: Coupling to Quantum Nuclear Motion and Decoherence2017Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 118, nr 8, artikkel-id 083001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Knowledge about the electronic motion in molecules is essential for our understanding of chemical reactions and biological processes. The advent of attosecond techniques opens up the possibility to induce electronic motion, observe it in real time, and potentially steer it. A fundamental question remains the factors influencing electronic decoherence and the role played by nuclear motion in this process. Here, we simulate the dynamics upon ionization of the polyatomic molecules paraxylene and modified bismethylene-adamantane, with a quantum mechanical treatment of both electron and nuclear dynamics using the direct dynamics variational multiconfigurational Gaussian method. Our simulations give new important physical insights about the expected decoherence process. We have shown that the decoherence of electron dynamics happens on the time scale of a few femtoseconds, with the interplay of different mechanisms: the dephasing is responsible for the fast decoherence while the nuclear overlap decay may actually help maintain it and is responsible for small revivals.

  • 520. Valencia, S.
    et al.
    Kleibert, A.
    Gaupp, A.
    Rusz, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Legut, Dominik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Bansmann, J.
    Gudat, W.
    Oppeneer, Peter M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Quadratic X-Ray Magneto-Optical Effect upon Reflection in a Near-Normal-Incidence Configuration at the M Edges of 3d-Transition Metals2010Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, nr 18, s. 187401-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have observed a quadratic x-ray magneto-optical effect in near-normal-incidence reflection at the M edges of iron. The effect appears as the magnetically induced rotation of similar to 0.1 degrees of the polarization plane of linearly polarized x-ray radiation upon reflection. A comparison of the measured rotation spectrum with results from x-ray magnetic linear dichroism data demonstrates that this is the first observation of the Schafer-Hubert effect in the x-ray regime. Ab initio density-functional theory calculations reveal that hybridization effects of the 3p core states necessarily need to be considered when interpreting experimental data. The discovered magneto-x-ray effect holds promise for future ultrafast and element-selective studies of ferromagnetic as well as antiferromagnetic materials.

  • 521.
    van der Spoel, David
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Beräknings- och systembiologi.
    Seibert, M Marvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Protein folding kinetics and thermodynamics from atomistic simulations2006Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 96, nr 23, s. 238102-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Determining protein folding kinetics and thermodynamics from all-atom molecular dynamics (MD) simulations without using experimental data represents a formidable scientific challenge because simulations can easily get trapped in local minima on rough free energy landscapes. This necessitates the computation of multiple simulation trajectories, which can be independent from each other or coupled in some manner, as, for example, in the replica exchange MD method. Here we present results obtained with a new analysis tool that allows the deduction of faithful kinetics data from a heterogeneous ensemble of simulation trajectories. The method is demonstrated on the decapeptide Chignolin for which we predict folding and unfolding time constants of 1.0±0.3 and 2.6±0.4  μs, respectively. We also derive the energetics of folding, and calculate a realistic melting curve for Chignolin.

  • 522. Vinko, S. M.
    et al.
    Zastrau, U.
    Mazevet, S.
    Andreasson, Jakob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Bajt, S.
    Burian, T.
    Chalupsky, J.
    Chapman, H. N.
    Cihelka, J.
    Doria, D.
    Doeppner, T.
    Duesterer, S.
    Dzelzainis, T.
    Faeustlin, R. R.
    Fortmann, C.
    Foerster, E.
    Galtier, E.
    Glenzer, S. H.
    Goede, S.
    Gregori, G.
    Hajdu, Janos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Hajkova, V.
    Heimann, P. A.
    Irsig, R.
    Juha, L.
    Jurek, M.
    Krzywinski, J.
    Laarmann, T.
    Lee, H. J.
    Lee, R. W.
    Li, B.
    Meiwes-Broer, K. -H
    Mithen, J. P.
    Nagler, B.
    Nelson, A. J.
    Przystawik, A.
    Redmer, R.
    Riley, D.
    Rosmej, F.
    Sobierajski, R.
    Tavella, F.
    Thiele, R.
    Tiggesbaeumker, J.
    Toleikis, S.
    Tschentscher, T.
    Vysin, L.
    Whitcher, T. J.
    White, S.
    Wark, J. S.
    Electronic Structure of an XUV Photogenerated Solid-Density Aluminum Plasma2010Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, nr 22, s. 225001-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By use of high intensity XUV radiation from the FLASH free-electron laser at DESY, we have created highly excited exotic states of matter in solid-density aluminum samples. The XUV intensity is sufficiently high to excite an inner-shell electron from a large fraction of the atoms in the focal region. We show that soft-x-ray emission spectroscopy measurements reveal the electronic temperature and density of this highly excited system immediately after the excitation pulse, with detailed calculations of the electronic structure, based on finite-temperature density functional theory, in good agreement with the experimental results.

  • 523.
    Vinogradov, Nikolay A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Zakharov, A. A.
    Kocevski, Vancho
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Rusz, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Simonov, K. A.
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Mikkelsen, A.
    Lundgren, E.
    Vinogradov, A. S.
    Mårtensson, Nils
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Yt- och gränsskiktsvetenskap.
    Preobrajenski, A. B.
    Formation and Structure of Graphene Waves on Fe(110)2012Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 109, nr 2, s. 026101-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A very rich Fe-C phase diagram makes the formation of graphene on iron surfaces a challenging task. Here we demonstrate that the growth of graphene on epitaxial iron films can be realized by chemical vapor deposition at relatively low temperatures, and that the formation of carbides can be avoided in excess of the carbon-containing precursors. The resulting graphene monolayer creates a novel periodically corrugated pattern on Fe(110). Using low-energy electron microscopy and scanning tunneling microscopy, we show that it is modulated in one dimension forming long waves with a period of similar to 4 nm parallel to the [001] direction of the substrate, with an additional height modulation along the wave crests. The observed topography of the graphene/Fe superstructure is well reproduced by density functional theory calculations, and found to result from a unique combination of the lattice mismatch and strong interfacial interaction, as probed by core-level photoemission and x-ray absorption spectroscopy.

  • 524.
    Wahlberg, C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Geodesic acoustic mode induced by toroidal rotation in tokamaks2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 11, s. 115003-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of toroidal rotation on the geodesic acoustic mode (GAM) in a tokamak is studied. It is shown that, in addition to a small frequency upshift of the ordinary GAM, another GAM, with much lower frequency, is induced by the rotation. The new GAM appears as a consequence of the nonuniform plasma density and pressure created by the centrifugal force on the magnetic surfaces. Both GAMs in a rotating plasma are shown to exist both as continuum modes with finite mode numbers m and n at the rational surfaces q = m/n as well as in the form of axisymmetric modes with m = n = 0.

  • 525. Wamers, F
    et al.
    Marganiec, J
    Aksouh, F
    Aksyutina, Yu
    Álvarez-Pol, H
    Aumann, T
    Beceiro-Novo, S
    Boretzky, K
    Borge, M J G
    Chartier, M
    Chatillon, A
    Chulkov, L V
    Cortina-Gil, D
    Emling, H
    Ershova, O
    Fraile, L M
    Fynbo, H O U
    Galaviz, D
    Geissel, H
    Heil, M
    Hoffmann, D H H
    Johansson, H T
    Jonson, B
    Karagiannis, C
    Kiselev, O A
    Kratz, J V
    Kulessa, R
    Kurz, N
    Langer, C
    Lantz, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Le Bleis, T
    Lemmon, R
    Litvinov, Yu A
    Mahata, K
    Müntz, C
    Nilsson, T
    Nociforo, C
    Nyman, G
    Ott, W
    Panin, V
    Paschalis, S
    Perea, A
    Plag, R
    Reifarth, R
    Richter, A
    Rodriguez-Tajes, C
    Rossi, D
    Riisager, K
    Savran, D
    Schrieder, G
    Simon, H
    Stroth, J
    Sümmerer, K
    Tengblad, O
    Weick, H
    Wimmer, C
    Zhukov, M V
    First Observation of the Unbound Nucleus 15Ne2014Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, nr 13, s. 132502-1-132502-5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on the first observation of the unbound proton-rich nucleus 15Ne. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u 17Ne. The 15Ne ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to 13O with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2 and 1 states in 14F is observed. The 15Ne ground state is shown to have a strong configuration with two protons in the (sd) shell around 13O with a 63(5)% (1s1/2)2 component.

  • 526.
    Wessely, Ola
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Skubic, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Nordström, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Current Driven Magnetization Dynamics in Helical Spin Density Waves2006Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 96, nr 25, artikkel-id 256601Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mechanism is proposed for manipulating the magnetic state of a helical spin density wave using a current. It is shown that a current through a bulk metal with a helical spin density wave induces a spin transfer torque, which gives rise to a rotation of the order parameter. The use of spin transfer torque to manipulate the magnetization in bulk systems does not suffer from the obstacles seen for magnetization reversal using interface spin transfer torque in multilayered systems. The effect is demonstrated by a quantitative calculation of the current induced magnetization dynamics of a rare earth metal, Er. Finally, we propose a setup for experimental verification.

  • 527.
    Westerström, Rasmus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Uldry, Anne-Christine
    Stania, Roland
    Dreiser, Jan
    Piamonteze, Cinthia
    Muntwiler, Matthias
    Matsui, Fumihiko
    Rusponi, Stefano
    Brune, Harald
    Yang, Shangfeng
    Popov, Alexey
    Büchner, Bernd
    Delley, Bernard
    Greber, Thomas
    Surface Aligned Magnetic Moments and Hysteresis of an Endohedral Single-Molecule Magnet on a Metal2015Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 114, nr 8, artikkel-id 087201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interaction between the endohedral unit in the single-molecule magnet Dy2ScN@C-80 and a rhodium (111) substrate leads to alignment of the Dy 4f orbitals. The resulting orientation of the Dy2ScN plane parallel to the surface is inferred from comparison of the angular anisotropy of x-ray absorption spectra and multiplet calculations in the corresponding ligand field. The x-ray magnetic circular dichroism is also angle dependent and signals strong magnetocrystalline anisotropy. This directly relates geometric and magnetic structure. Element specific magnetization curves from different coverages exhibit hysteresis at a sample temperature of similar to 4 K. From the measured hysteresis curves, we estimate the zero field remanence lifetime during x-ray exposure of a submonolayer to be about 30 seconds.

  • 528.
    Wilder, F. D.
    et al.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80303 USA..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80303 USA.;Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80303 USA..
    Eriksson, S.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80303 USA..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Ahmadi, N.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80303 USA..
    Goodrich, K. A.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80303 USA.;Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80303 USA..
    Newman, D. L.
    Univ Colorado, Dept Phys, Boulder, CO 80303 USA..
    Trattner, K. J.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80303 USA..
    Torbert, R. B.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria..
    Lindqvist, P. -A
    Khotyaintsev, Yuri V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Multipoint Measurements of the Electron Jet of Symmetric Magnetic Reconnection with a Moderate Guide Field2017Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 118, nr 26, artikkel-id 265101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report observations from the Magnetospheric Multiscale (MMS) satellites of the electron jet in a symmetric magnetic reconnection event with moderate guide field. All four spacecraft sampled the ion diffusion region and observed the electron exhaust. The observations suggest that the presence of the guide field leads to an asymmetric Hall field, which results in an electron jet skewed towards the separatrix with a nonzero component along the magnetic field. The jet appears in conjunction with a spatially and temporally persistent parallel electric field ranging from -3 to -5 mV/m, which led to dissipation on the order of 8 nW/m(3). The parallel electric field heats electrons that drift through it, and is associated with a streaming instability and electron phase space holes.

  • 529.
    Willems, F.
    et al.
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2A, D-12489 Berlin, Germany.
    Sharma, S.
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2A, D-12489 Berlin, Germany.
    Schmising, C. von Korff
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2A, D-12489 Berlin, Germany.
    Dewhurst, J. K.
    Max Planck Inst Microstruct Phys, Weinberg 2, D-06120 Halle, Saale, Germany.
    Salemi, Leandro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Schick, D.
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2A, D-12489 Berlin, Germany.
    Hessing, P.
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2A, D-12489 Berlin, Germany.
    Strueber, C.
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2A, D-12489 Berlin, Germany.
    Engel, W. D.
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2A, D-12489 Berlin, Germany.
    Eisebitt, S.
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2A, D-12489 Berlin, Germany;Tech Univ Berlin, Inst Opt & Atomare Phys, D-10623 Berlin, Germany.
    Magneto-Optical Functions at the 3p Resonances of Fe, Co, and Ni: Ab initio Description and Experiment2019Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 122, nr 21, artikkel-id 217202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present experimental data and a complete theoretical description of the magneto-optical contributions to the complex refractive index in the extreme ultraviolet (XUV) range covering the 3p resonances of Fe, Co, and Ni. The direct comparison of the two allows us to conclude that many-body corrections to the ground state and local field effects are crucial for an accurate description of M-edge spectra. Our results are relevant for investigation of static magnetization, via XUV spectroscopy of multielement systems, as well as the dynamics of magnetization, as needed in the study of femtomagnetism and spintronics.

  • 530.
    Wolf, Matthew J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Kullgren, Jolla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Comment on: "Clustering of Oxygen Vacancies at CeO2(111): Critical Role of Hydroxyls"2016Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 117, nr 27, artikkel-id 279601Artikkel i tidsskrift (Fagfellevurdert)
  • 531.
    Wolf, Matthew J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Kullgren, Jolla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Comment on "Clustering og Oxygen Vacancies at CeO2(111): Crytical Role of Hydroxyls"2016Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114Artikkel i tidsskrift (Fagfellevurdert)
  • 532.
    Wolff, Max
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Devishvili, Anton
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik. Inst Laue Langevin, 71 Ave Martyrs, F-38000 Grenoble, France.
    Dura, Joseph A.
    NIST, NIST Ctr Neutron Res, 100 Bur Dr, Gaithersburg, MD 20899 USA.
    Adlmann, Franz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Kitchen, Brian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Pálsson, Gunnar K.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Palonen, Heikki
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Maranville, Brian B.
    NIST, NIST Ctr Neutron Res, 100 Bur Dr, Gaithersburg, MD 20899 USA.
    Majkrzak, Charles F.
    NIST, NIST Ctr Neutron Res, 100 Bur Dr, Gaithersburg, MD 20899 USA.
    Toperverg, Boris P.
    Petersburg Nucl Phys Inst, Gatchina 188300, Russia;Inst Laue Langevin, 71 Ave Martyrs, F-38000 Grenoble, France.
    Nuclear Spin Incoherent Neutron Scattering from Quantum Well Resonators2019Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 123, nr 1, artikkel-id 016101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the detection and quantification of nuclear spin incoherent scattering from hydrogen occupying interstitial sites in a thin film of vanadium. The neutron wave field is enhanced in a quantum resonator with magnetically switchable boundaries. Our results provide a pathway for the study of dynamics at surfaces and in ultrathin films using inelastic and/or quasielastic neutron scattering methods.

  • 533.
    Xin, Xiao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Pálsson, Gunnar Karl
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Wolff, Max
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Hjörvarsson, Björgvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Finite-Size Effects: Hydrogen in Fe/V(001) Superlattices2014Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 113, nr 4, s. 046103-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the effect of finite size on phase boundaries of hydride formation in ultrathin metallic films, using Fe/V(001) superlattices as a model system. The critical temperature is determined to scale linearly with the inverse thickness of the V layers. The decrease of the ordering temperature with decreasing layer thickness arises from the missing H neighbors at the interfaces, analogous to observed finite-size effects in magnetic layers and nanosized ice crystals.

  • 534. Xu, G.F.
    et al.
    Zhang, J.
    Dept. of Physics, Shandong University, China.
    Tong, Dianmin
    Dept. of Physics, Shandong University, China.
    Sjöqvist, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Kwek, L.C.
    Centre for Quantum Technologies, NUS, Singapore.
    Non-adiabatic holonomic quantum computation in decoherence-free subspaces2012Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 109, nr 17, artikkel-id 170501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quantum computation that combines the coherence stabilization virtues of decoherence-free subspaces and the fault tolerance of geometric holonomic control is of great practical importance. Some schemes of adiabatic holonomic quantum computation in decoherence-free subspaces have been proposed in the past few years. However, non-adiabatic holonomic quantum computation in decoherence-free subspaces, which avoids long run-time requirement but with all the robust advantages, remains an open problem. Here, we demonstrate how to realize non-adiabatic holonomic quantum computation in decoherence-free subspaces. By using only three neighboring physical qubits undergoing collective dephasing to encode one logical qubit, we realize a universal set of quantum gates. 

  • 535. Ye, F
    et al.
    Chi, S X
    Fernandez-Baca, J A
    Moreo, A
    Dagotto, E
    Lynn, J W
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kaneko, Y
    Tokura, Y
    Dai, P C
    Electronic Self-Organization in the Single-Layer Manganite Pr1-xCa1+xMnO42009Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, nr 16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We use neutron scattering to investigate the doping evolution of the magnetic correlations in the single-layer manganite Pr1-xCa1-xMnO4, away from the x = 0.5 composition where the CE-type commensurate antiferromagnetic (AF) structure is stable. We find that short-range incommensurate spin correlations develop as the system is electron doped (x < 0.5), which coexist with the CE-type AF order. This suggests that electron doping in this system induces an inhomogeneous electronic self-organization, where commensurate AF patches with x = 0.5 are separated by electron-rich domain walls with short-range magnetic correlations. This behavior is strikingly different than for the perovskite Pr1-xCaxMnO3, where the long-range CE-type commensurate AF structure is stable over a wide range of electron or hole doping around x = 0.5.

  • 536.
    Yim, C. M.
    et al.
    UCL, Dept Chem, 20 Gordon St, London WC1H 0AJ, England; UCL, London Ctr Nanotechnol, 20 Gordon St, London WC1H 0AJ, England.
    Watkins, M. B,
    Lincoln Univ, Sch Math & Phys, Lincoln LN6 7TS, England.
    Wolf, Matthew
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. UCL, Dept Phys & Astron, Gower St, London WC1E 6BT, England; UCL, London Ctr Nanotechnol, Gower St, London WC1E 6BT, England.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Thornton, G.
    UCL, Dept Chem, 20 Gordon St, London WC1H 0AJ, England; UCL, London Ctr Nanotechnol, 20 Gordon St, London WC1H 0AJ, England.
    Engineering Polarons at a Metal Oxide Surface2016Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 117, nr 11, artikkel-id 116402Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polarons in metal oxides are important in processes such as catalysis, high temperature superconductivity, and dielectric breakdown in nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO2(110), using a combination of low temperature scanning tunneling microscopy (STM), density functional theory, and classical molecular dynamics calculations. We find that the electrons are symmetrically distributed around isolated vacancies at 78 K, but as the temperature is reduced, their distributions become increasingly asymmetric, confirming their polaronic nature. By manipulating isolated vacancies with the STM tip, we show that particular configurations of polarons are preferred for given locations of the vacancies, which we ascribe to small residual electric fields in the surface. We also form a series of vacancy complexes and manipulate the Ti ions surrounding them, both of which change the associated electronic distributions. Thus, we demonstrate that the configurations of polarons can be engineered, paving the way for the construction of conductive pathways relevant to resistive switching devices.

  • 537. Yim, C.M.
    et al.
    Watkins, M.B.
    Pang, C.L.
    Wolf, Matthew J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Thornton, G,
    Engeneering Polarons at a Metal Oxide Syrface2016Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114Artikkel i tidsskrift (Fagfellevurdert)
  • 538.
    Yordanova, Emiliya
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    André, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Buchert, Stephan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Voeroes, Z.
    Magnetosheath plasma turbulence and its spatiotemporal evolution as observed by the Cluster spacecraft2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, nr 20, s. 205003-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study the plasma turbulence, at scales larger than the ion inertial length scale, downstream of a quasiparallel bow shock using Cluster multispacecraft measurements. We show that turbulence is intermittent and well described by the extended structure function model, which takes into account the spatial inhomogeneity of the cascade rate. For the first time we use multispacecraft observations to characterize the evolution of magnetosheath turbulence, particularly its intermittency, as a function of the distance from the bow shock. The intermittency significantly changes over the distance of the order of 100 ion inertial lengths, being increasingly stronger and anisotropic away from the bow shock.

  • 539.
    You, Wenjing
    et al.
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Tengdin, Phoebe
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Chen, Cong
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Shi, Xun
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Zusin, Dmitriy
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Zhang, Yingchao
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Gentry, Christian
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Blonsky, Adam
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Keller, Mark
    NIST, 325 Broadway, Boulder, CO 80305 USA.
    Oppeneer, Peter M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Kapteyn, Henry
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Tao, Zhensheng
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;Fudan Univ, Dept Phys, State Key Lab Surface Phys, Shanghai 200438, Peoples R China;NIST, Boulder, CO 80309 USA.
    Murnane, Margaret
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA;Univ Colorado, JILA, Boulder, CO 80309 USA;NIST, Boulder, CO 80309 USA.
    Revealing the Nature of the Ultrafast Magnetic Phase Transition in Ni by Correlating Extreme Ultraviolet Magneto-Optic and Photoemission Spectroscopies2018Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, nr 7, artikkel-id 077204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By correlating time-and angle-resolved photoemission and time-resolved transverse magneto-optical Kerr effect measurements, both at extreme ultraviolet wavelengths, we uncover the universal nature of the ultrafast photoinduced magnetic phase transition in Ni. This allows us to explain the ultrafast magnetic response of Ni at all laser fluences-from a small reduction of the magnetization at low laser fluences, to complete quenching at high laser fluences. Both probe methods exhibit the same demagnetization and recovery timescales. The spin system absorbs the energy required to proceed through a magnetic phase transition within 20 fs after the peak of the pump pulse. However, the spectroscopic signatures of demagnetization of the material appear only after approximate to 200 fs and the subsequent recovery of magnetization on timescales ranging from 500 fs to >70 ps. We also provide evidence of two competing channels with two distinct timescales in the recovery process that suggest the presence of coexisting phases in the material.

  • 540.
    Yudin, Dmitry
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Hirschmeier, Daniel
    Hafermann, Hartmut
    Eriksson, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Lichtenstein, Alexander I.
    Katsnelson, Mikhail I.
    Fermi Condensation Near van Hove Singularities Within the Hubbard Model on the Triangular Lattice2014Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, nr 7, s. 070403-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The proximity of the Fermi surface to van Hove singularities drastically enhances interaction effects and leads to essentially new physics. In this work we address the formation of flat bands ("Fermi condensation") within the Hubbard model on the triangular lattice and provide a detailed analysis from an analytical and numerical perspective. To describe the effect we consider both weak-coupling and strong-coupling approaches, namely the renormalization group and dual fermion methods. It is shown that the band flattening is driven by correlations and is well pronounced even at sufficiently high temperatures, of the order of 0.1-0.2 of the hopping parameter. The effect can therefore be probed in experiments with ultracold fermions in optical lattices.

  • 541.
    Zhong, Z. H.
    et al.
    Nanchang Univ, Sch Sci, Dept Phys, Nanchang 330031, Jiangxi, Peoples R China.;Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China.;Nanchang Univ, Sch Resources Environm & Chem Engn, Nanchang 330031, Jiangxi, Peoples R China..
    Tang, R. X.
    Nanchang Univ, Sch Sci, Dept Phys, Nanchang 330031, Jiangxi, Peoples R China.;Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China..
    Zhou, M.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China.;Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Deng, X. H.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China..
    Pang, Y.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Tobert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA..
    Ergun, R. E.
    Univ Colorado LASP, Boulder, CO 80303 USA..
    Khotyaintsev, Yuri V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Lindquist, P. -A
    Evidence for Secondary Flux Rope Generated by the Electron Kelvin-Helmholtz Instability in a Magnetic Reconnection Diffusion Region2018Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 120, nr 7, artikkel-id 075101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Secondary flux ropes are suggested to play important roles in energy dissipation and particle acceleration during magnetic reconnection. However, their generation mechanism is not fully understood. In this Letter, we present the first direct evidence that a secondary flux rope was generated due to the evolution of an electron vortex, which was driven by the electron Kelvin-Helmholtz instability in an ion diffusion region as observed by the Magnetospheric Multiscale mission. The subion scale (less than the ion inertial length) flux rope was embedded within the electron vortex, which contained a secondary electron diffusion region at the trailing edge of the flux rope. We propose that intense electron shear flow produced by reconnection generated the electron Kelvin-Helmholtz vortex, which induced a secondary reconnection in the exhaust of the primary X line and then led to the formation of the flux rope. This result strongly suggests that secondary electron Kelvin-Helmholtz instability is important for reconnection dynamics.

  • 542.
    Zhou, M.
    et al.
    Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Berchem, J.
    Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Walker, R. J.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA..
    El-Alaoui, M.
    Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Deng, X.
    Nanchang Univ, Nanchang 330031, Jiangxi, Peoples R China..
    Cazzola, E.
    Katholieke Univ Leuven, Dept Math, Ctr Plasma Astrophys, B-3001 Leuven, Belgium..
    Lapenta, G.
    Katholieke Univ Leuven, Dept Math, Ctr Plasma Astrophys, B-3001 Leuven, Belgium..
    Goldstein, M. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Space Sci Inst, Boulder, CO 80301 USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Pang, Y.
    Nanchang Univ, Nanchang 330031, Jiangxi, Peoples R China..
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80303 USA..
    Lavraud, B.
    Univ Toulouse, CNRS, Inst Rech Astrophys & Planetol, UPS,CNES, F-31028 Toulouse, France..
    Liang, H.
    Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA..
    Zhao, C.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Lindqvist, P. -A
    Marklund, G.
    Royal Inst Technol, SE-11428 Stockholm, Sweden..
    Wilder, F. D.
    Univ Colorado, LASP, Boulder, CO 80303 USA..
    Khotyaintsev, Yuri V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Coalescence of Macroscopic Flux Ropes at the Subsolar Magnetopause: Magnetospheric Multiscale Observations2017Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 119, nr 5, artikkel-id 055101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report unambiguous in situ observation of the coalescence of macroscopic flux ropes by the magnetospheric multiscale (MMS) mission. Two coalescing flux ropes with sizes of similar to 1 R-E were identified at the subsolar magnetopause by the occurrence of an asymmetric quadrupolar signature in the normal component of the magnetic field measured by the MMS spacecraft. An electron diffusion region (EDR) with a width of four local electron inertial lengths was embedded within the merging current sheet. The EDR was characterized by an intense parallel electric field, significant energy dissipation, and suprathermal electrons. Although the electrons were organized by a large guide field, the small observed electron pressure nongyrotropy may be sufficient to support a significant fraction of the parallel electric field within the EDR. Since the flux ropes are observed in the exhaust region, we suggest that secondary EDRs are formed further downstream of the primary reconnection line between the magnetosheath and magnetospheric fields.

  • 543. Zitnik, M
    et al.
    Mihelič, A
    Bučar, K
    Kavčič, M
    Rubensson, Jan-Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Svanqvist, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Söderström, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Feifel, Raimund
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Såthe, C
    Ovcharenko, Y
    Lyamayev, V
    Mazza, T
    Meyer, M
    Simon, M
    Journel, L
    Lüning, J
    Plekan, O
    Coreno, M
    Devetta, M
    Di Fraia, M
    Finetti, P
    Richter, R
    Grazioli, C
    Prince, K C
    Callegari, C
    High resolution multiphoton spectroscopy by a tunable free-electron-laser light2014Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 113, nr 19, s. 193201-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seeded free electron lasers theoretically have the intensity, tunability, and resolution required for multiphoton spectroscopy of atomic and molecular species. Using the seeded free electron laser FERMI and a novel detection scheme, we have revealed the two-photon excitation spectra of dipole-forbidden doubly excited states in helium. The spectral profiles of the lowest (-1,0)^{+1} ^{1}S^{e} and (0,1)^{0} ^{1}D^{e} resonances display energy shifts in the meV range that depend on the pulse intensity. The results are explained by an effective two-level model based on calculated Rabi frequencies and decay rates.

  • 544.
    Åsman, B.
    et al.
    Uppsala universitet.
    Belanger-Champagne, C.
    Uppsala universitet.
    Gollub, N.
    Uppsala universitet.
    Strandberg, S.
    Uppsala universitet.
    Search for long-lived particles decaying into electron or photon pairs with the D0 detector2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 11, s. 111802-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this Letter we report on a search for long-lived particles that decay into final states with two electrons or photons. Such long-lived particles arise in a variety of theoretical models, such as hidden valleys and supersymmetry with gauge-mediated breaking. By precisely reconstructing the direction of the electromagnetic shower we are able to probe much longer lifetimes than previously explored. We see no evidence of the existence of such long-lived particles and interpret this search as a quasi model-independent limit on their production cross section, as well as a limit on a long-lived fourth generation quark.

  • 545.
    Åsman, B.
    et al.
    Uppsala universitet.
    Belanger-Champagne, Camille
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärn- och partikelfysik.
    Gollub, N.
    Uppsala universitet.
    Strandberg, S.
    Uppsala universitet.
    Measurement of the Electron Charge Asymmetry in p(p)over-bar -> W plus X -> e nu plus X Events at root s=1.96 TeV2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 21, s. 211801-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a measurement of the electron charge asymmetry in p (p) over bar -> W + X -> e nu + X events at a center of mass energy of 1.96 TeV using 0.75 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider. The asymmetry is measured as a function of the electron transverse momentum and pseudorapidity in the interval (-3.2, 3.2) and is compared with expectations from next-to-leading order calculations in perturbative quantum chromodynamics. These measurements will allow more accurate determinations of the proton parton distribution functions.

  • 546.
    Åsman, B.
    et al.
    Uppsala universitet.
    Belanger-Champagne, Camille
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärn- och partikelfysik.
    Gollub, N.
    Uppsala universitet.
    Strandberg, S.
    Uppsala universitet.
    Measurement of the Polarization of the Upsilon(1S) and Upsilon(2S) States in pp Collisions at s=1.96 TeV2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 18, s. 182004-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a study of the polarization of the Upsilon(1S) and Upsilon(2S) states using a 1.3 fb(-1) data sample collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron Collider. We measure the polarization parameter alpha=(sigma(T)-2 sigma(L))/(sigma(T)+2 sigma(L)), where sigma(T) and sigma(L) are the transversely and longitudinally polarized components of the production cross section, as a function of the transverse momentum (p(T)(Upsilon)) for the Upsilon(1S) and Upsilon(2S). Significant p(T)(Upsilon)-dependent longitudinal polarization is observed for the Upsilon(1S). A comparison with theoretical models is presented.

  • 547.
    Åsman, B.
    et al.
    Uppsala universitet.
    Belanger-Champagne, Camille
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärn- och partikelfysik.
    Gollub, N.
    Uppsala universitet.
    Strandberg, S.
    Uppsala universitet.
    Precise Measurement of the Top-Quark Mass from lepton plus jets Events2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 18, s. 182001-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We measure the mass of the top quark using top-quark pair candidate events in the lepton+jets channel from data corresponding to 1 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron collider. We use a likelihood technique that reduces the jet energy scale uncertainty by combining an in situ jet energy calibration with the independent constraint on the jet energy scale (JES) from the calibration derived using photon+jets and dijet samples. We find the mass of the top quark to be 171.5 +/- 1.8(stat.+JES)+/- 1.1(syst.) GeV.

  • 548.
    Åsman, B.
    et al.
    Uppsala universitet.
    Belanger-Champagne, Camille
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärn- och partikelfysik.
    Gollub, N.
    Uppsala universitet.
    Strandberg, S.
    Uppsala universitet.
    Search for Anomalous Wtb Couplings in Single Top Quark Production2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 22, s. 221801-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In 0.9 fb(-1) of pp collisions, the D0 Collaboration presented evidence for single top quark production in events with an isolated lepton, missing transverse momentum, and two to four jets. We examine these data to study the Lorentz structure of the Wtb coupling. The standard model predicts a left-handed vector coupling at the Wtb vertex. The most general lowest dimension, CP-conserving Lagrangian admits right-handed vector and left- or right-handed tensor couplings as well. We find that the data prefer the left-handed vector coupling and set upper limits on the anomalous couplings. These are the first direct constraints on a general Wtb interaction and the first direct limits on left- and right-handed tensor couplings.

  • 549.
    Åsman, B.
    et al.
    Uppsala universitet.
    Belanger-Champagne, Camille
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Kärn- och partikelfysik.
    Gollub, N.
    Uppsala universitet.
    Strandberg, S.
    Uppsala universitet.
    Search for Neutral Higgs Bosons in Multi-b-Jet Events in pp Collisions at s=1.96 TeV2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 22, s. 221802-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Data recorded by the D0 experiment at the Fermilab Tevatron Collider are analyzed to search for neutral Higgs bosons produced in association with b quarks. This production mode can be enhanced in the minimal supersymmetric standard model (MSSM). The search is performed in the three b quark channel using multijet triggered events corresponding to an integrated luminosity of 1 fb(-1). No statistically significant excess of events with respect to the predicted background is observed and limits are set in the MSSM parameter space.

  • 550.
    Åsman, B.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Bélanger-Champagne, Camille
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Gollub, N.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Strandberg, S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Measurement of the Forward-Backward Charge Asymmetry and Extraction of sin(2)theta(eff)(W) in pp -> Z/gamma(*)+X -> e(+)e(-)+X Events Produced at s=1.96 TeV2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 19, s. 191801-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a measurement of the forward-backward charge asymmetry (A(FB)) in pp -> Z/gamma(*)+X -> e(+)e(-)+X events at a center-of-mass energy of 1.96 TeV using 1.1 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron collider. A(FB) is measured as a function of the invariant mass of the electron-positron pair, and found to be consistent with the standard model prediction. We use the A(FB) measurement to extract the effective weak mixing angle sin(2)theta(eff)(W)=0.2326 +/- 0.0018(stat)+/- 0.0006(syst).

89101112 501 - 550 of 552
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