- Erratum: Lattice Calculation of Non-Gaussian Density Perturbations from the Massless Preheating Inflationary Model [Phys. Rev. Lett. 100, 041302 (2008)]
Author(s): Alex Chambers and Arttu Rajantie
[Phys. Rev. Lett. 101, 149903] Published Fri Oct 03, 2008
- Cell Sorting in Three Dimensions: Topology, Fluctuations, and Fluidlike Instabilities
Author(s): M. Shane Hutson, G. Wayne Brodland, Justina Yang, and Denis Viens
Previous 2D and 3D models concluded that cell sorting requires cytoskeletal fluctuations and is stalled by high tension at heterotypic interfaces. New deterministic and stochastic models show that this is not true in 3D. Sorting in 3D involves both topological untangling and domain coalescence. Coal...
[Phys. Rev. Lett. 101, 148105] Published Fri Oct 03, 2008
- Fingerprints of Amorphous Icelike Behavior in the Vibrational Density of States of Protein Hydration Water
Author(s): A. Paciaroni, A. Orecchini, E. Cornicchi, M. Marconi, C. Petrillo, M. Haertlein, M. Moulin, H. Schober, M. Tarek, and F. Sacchetti
The low-frequency modes of protein hydration water are investigated by inelastic neutron scattering. Experiments on both protonated and fully deuterated maltose binding protein samples allow us to unambiguously single out the contribution from water. The low-energy vibrational density of states of h...
[Phys. Rev. Lett. 101, 148104] Published Fri Oct 03, 2008
- Evidence for Dark Excitons in a Single Carbon Nanotube due to the Aharonov-Bohm Effect
Author(s): Ryusuke Matsunaga, Kazunari Matsuda, and Yoshihiko Kanemitsu
We studied exciton structures and the Aharonov-Bohm effect in a single carbon nanotube using micro-photoluminescence (PL) spectroscopy under a magnetic field at low temperatures. A single sharp PL peak from the bright exciton state of a single carbon nanotube was observed under zero magnetic field, ...
[Phys. Rev. Lett. 101, 147404] Published Fri Oct 03, 2008
- Influence of Strain on the Conduction Band Structure of Strained Silicon Nanomembranes
Author(s): C. Euaruksakul, Z. W. Li, F. Zheng, F. J. Himpsel, C. S. Ritz, B. Tanto, D. E. Savage, X. S. Liu, and M. G. Lagally
The influence of in-plane biaxial strain on the conduction bands of Si is explored using elastically strained Si(001) nanomembranes and high-resolution x-ray absorption measurements with electron yield detection. The strain-induced splitting of the conduction band minimum and the energy shifts of tw...
[Phys. Rev. Lett. 101, 147403] Published Fri Oct 03, 2008
- Anomalous Photogalvanic Effect of Circularly Polarized Light Incident on the Two-Dimensional Electron Gas in Al_{x} Ga_{1-x} N/GaN Heterostructures at Room Temperature
Author(s): X. W. He, B. Shen, Y. H. Chen, Q. Zhang, K. Han, C. M. Yin, N. Tang, F. J. Xu, C. G. Tang, Z. J. Yang, Z. X. Qin, G. Y. Zhang, and Z. G. Wang
Under normal incidence of circularly polarized light at room temperature, a charge current with swirly distribution has been observed in the two-dimensional electron gas in Al_{0.25} Ga_{0.75} N/GaN heterostructures. We believe that this anomalous charge current is produced by a radial spin current ...
[Phys. Rev. Lett. 101, 147402] Published Fri Oct 03, 2008
- Rotation of the Pinning Direction in the Exchange Bias Training Effect in Polycrystalline NiFe/FeMn Bilayers
Author(s): X. P. Qiu, D. Z. Yang, S. M. Zhou, R. Chantrell, K. O’Grady, U. Nowak, J. Du, X. J. Bai, and L. Sun
For polycrystalline NiFe/FeMn bilayers, we have observed and quantified the rotation of the pinning direction in the exchange bias training and recovery effects. During consecutive hysteresis loops, the rotation of the pinning direction strongly depends on the magnetization reversal mechanism of the...
[Phys. Rev. Lett. 101, 147207] Published Fri Oct 03, 2008
- Electrical Control of Exchange Bias Mediated by Graphene
Author(s): Y. G. Semenov, J. M. Zavada, and K. W. Kim
The role of graphene in mediating the exchange interaction is theoretically investigated when placed between two ferromagnetic dielectric materials. The calculation based on a tight-binding model illustrates that the magnetic interactions at the interfaces affect not only the graphene band structure...
[Phys. Rev. Lett. 101, 147206] Published Fri Oct 03, 2008
- Size Dependence of Current Spin Polarization through Superconductor/Ferromagnet Nanocontacts
Author(s): M. Stokmaier, G. Goll, D. Weissenberger, C. Sürgers, and H. v. Löhneysen
The spin polarization P of the transport current through the interface between superconducting Al and ferromagnetic Fe is determined by means of Andreev reflection at nanostructured point contacts. We observe a systematic decrease of P with decreasing contact resistance. Our data provide evidence fo...
[Phys. Rev. Lett. 101, 147005] Published Fri Oct 03, 2008
- Spin Resonance in Three-Dimensional Superconductors: The Case of CeCoIn_{5}
Author(s): A. V. Chubukov and L. P. Gor’kov
The recent observation of resonance spin excitation at (1/2, 1/2, 1/2) in the superconducting state of CeCoIn_{5} [C. Stock , Phys. Rev. Lett. 100, 087001 (2008)] was interpreted as evidence for d_{x^{2} -y^{2} } gap symmetry, by analogy with cuprates. This is true if the resonance is a spin exciton...
[Phys. Rev. Lett. 101, 147004] Published Fri Oct 03, 2008
- Tuning the Effective Fine Structure Constant in Graphene: Opposing Effects of Dielectric Screening on Short- and Long-Range Potential Scattering
Author(s): C. Jang, S. Adam, J.-H. Chen, E. D. Williams, S. Das Sarma, and M. S. Fuhrer
We reduce the dimensionless interaction strength α in graphene by adding a water overlayer in ultrahigh vacuum, thereby increasing dielectric screening. The mobility limited by long-range impurity scattering is increased over 30%, due to the background dielectric constant enhancement leading to a r...
[Phys. Rev. Lett. 101, 146805] Published Fri Oct 03, 2008
- Self-Alignment of Co Adatoms on In Atomic Wires by Quasi-One-Dimensional Electron-Gas-Meditated Interactions
Author(s): Canhua Liu, Takashi Uchihashi, and Tomonobu Nakayama
Low-density Co atoms are found to self-align on the Si(111)-(4×1)-In surface in the direction of In atomic wires at incommensurate adsorption sites. Indirect interaction between a pair of Co adatoms is investigated through a site distribution function of adatoms determined with scanning tunneling m...
[Phys. Rev. Lett. 101, 146104] Published Fri Oct 03, 2008
- Sublimation inside an Elastoplastic Material
Author(s): Valery I. Levitas and Nataliya Altukhova
Thermodynamic and kinetic approaches for sublimation inside elastoplastic material under tensile stress are developed for large strains. Various conceptual problems related to irreversible plastic deformation are addressed for a spherical bubble. They include definitions of the thermodynamic driving...
[Phys. Rev. Lett. 101, 145703] Published Fri Oct 03, 2008
- Stochastic Metallic-Glass Cellular Structures Exhibiting Benchmark Strength
Author(s): Marios D. Demetriou, Chris Veazey, John S. Harmon, Joseph P. Schramm, and William L. Johnson
By identifying the key characteristic “structural scales” that dictate the resistance of a porous metallic glass against buckling and fracture, stochastic highly porous metallic-glass structures are designed capable of yielding plastically and inheriting the high plastic yield strength of the am...
[Phys. Rev. Lett. 101, 145702] Published Fri Oct 03, 2008
- Size Scaling and Bursting Activity in Thermally Activated Breakdown of Fiber Bundles
Author(s): Naoki Yoshioka, Ferenc Kun, and Nobuyasu Ito
We study subcritical fracture driven by thermally activated damage accumulation in the framework of fiber bundle models. We show that in the presence of stress inhomogeneities, thermally activated cracking results in an anomalous size effect; i.e., the average lifetime ⟨t_{f} ⟩ decreases as a po...
[Phys. Rev. Lett. 101, 145502] Published Fri Oct 03, 2008
- Strong and Ductile Colossal Carbon Tubes with Walls of Rectangular Macropores
Author(s): Huisheng Peng, Daoyong Chen, Jian-Yu Huang, S. B. Chikkannanavar, J. Hänisch, Menka Jain, D. E. Peterson, S. K Doorn, Yunfeng Lu, Y. T. Zhu, and Q. X. Jia
We report a new type of carbon material—porous colossal carbon tubes. Compared with carbon nanotubes, colossal carbon tubes have a much bigger size, with a diameter of between 40 and 100 μm and a length in the range of centimeters. Significantly, the walls of the colossal tubes are composed ...
[Phys. Rev. Lett. 101, 145501] Published Fri Oct 03, 2008
- Tracking Quasiclassical Chaos in Ultracold Boson Gases
Author(s): Maxence Lepers, Véronique Zehnlé, and Jean Claude Garreau
We study the dynamics of an ultracold boson gas in a lattice submitted to a constant force. We track the route of the system towards chaos created by the many-body-induced nonlinearity and show that relevant information can be extracted from an experimentally accessible quantity, the gas mean positi...
[Phys. Rev. Lett. 101, 144103] Published Fri Oct 03, 2008
- Decay Control via Discrete-to-Continuum Coupling Modulation in an Optical Waveguide System
Author(s): F. Dreisow, A. Szameit, M. Heinrich, T. Pertsch, S. Nolte, A. Tünnermann, and S. Longhi
Control of optical tunneling via modulation of the coupling to the continuum is experimentally reported in femtosecond laser written waveguide arrays. The experiment demonstrates for optical tunneling in photonic lattices the universal mechanism of decay control recently proposed for quantum systems...
[Phys. Rev. Lett. 101, 143602] Published Fri Oct 03, 2008
- Scale-Renormalized Matrix-Product States for Correlated Quantum Systems
Author(s): Anders W. Sandvik
A generalization of matrix product states (MPS) for interacting quantum systems in two and three dimensions is introduced. These scale-renormalized matrix-product states (SR-MPS) are based on a coarse graining of the lattice in which the blocks at each level are associated with matrix products that...
[Phys. Rev. Lett. 101, 140603] Published Fri Oct 03, 2008
- Approximate Locality for Quantum Systems on Graphs
Author(s): Tobias J. Osborne
In this Letter we make progress on a long-standing open problem of Aaronson and Ambainis [Theory Comput. 1, 47 (2005)]: we show that if U is a sparse unitary operator with a gap Δ in its spectrum, then there exists an approximate logarithm H of U which is also sparse. The sparsity pattern of H gets...
[Phys. Rev. Lett. 101, 140503] Published Fri Oct 03, 2008
- Determination of the Superfluid Gap in Atomic Fermi Gases by Quasiparticle Spectroscopy
Author(s): André Schirotzek, Yong-il Shin, Christian H. Schunck, and Wolfgang Ketterle
We present majority and minority radio frequency spectra of strongly interacting imbalanced Fermi gases of ^{6} Li. We observed a smooth evolution in the nature of pairing correlations from pairing in the superfluid region to polaron binding in the highly polarized normal region. The imbalance induc...
[Phys. Rev. Lett. 101, 140403] Published Fri Oct 03, 2008
- Creep Motion of a Granular Pile Induced by Thermal Cycling
Author(s): Thibaut Divoux, Hervé Gayvallet, and Jean-Christophe Géminard
We report a time-resolved study of the dynamics associated with the slow compaction of a granular column submitted to thermal cycles. The column height displays a complex behavior: for a large amplitude of the temperature cycles, the granular column settles continuously, experiencing a small settlin...
[Phys. Rev. Lett. 101, 148303] Published Thu Oct 02, 2008
- Conformation of Circular DNA in Two Dimensions
Author(s): Guillaume Witz, Kristian Rechendorff, Jozef Adamcik, and Giovanni Dietler
The conformation of circular DNA molecules of various lengths adsorbed in a 2D conformation on a mica surface is studied. The results confirm the conjecture that the critical exponent ν is topologically invariant and equal to the self-avoiding walk value (in the present case ν=3/4), and that the t...
[Phys. Rev. Lett. 101, 148103] Published Thu Oct 02, 2008
- Dynamical Dzyaloshinsky-Moriya Interaction in KCuF_{3}
Author(s): M. V. Eremin, D. V. Zakharov, H.-A. Krug von Nidda, R. M. Eremina, A. Shuvaev, A. Pimenov, P. Ghigna, J. Deisenhofer, and A. Loidl
The spin dynamics of the prototypical quasi-one-dimensional antiferromagnetic Heisenberg spin S=1/2 chain KCuF_{3} is investigated by electron spin resonance spectroscopy. Our analysis shows that the peculiarities of the spin dynamics require a new dynamical form of the antisymmetric anisotropic spi...
[Phys. Rev. Lett. 101, 147601] Published Thu Oct 02, 2008
- Spin Waves and Quantum Criticality in the Frustrated XY Pyrochlore Antiferromagnet Er_{2} Ti_{2} O_{7}
Author(s): J. P. Ruff, J. P. Clancy, A. Bourque, M. A. White, M. Ramazanoglu, J. S. Gardner, Y. Qiu, J. R. Copley, M. B. Johnson, H. A. Dabkowska, and B. D. Gaulin
We report detailed measurements of the low temperature magnetic phase diagram of Er_{2} Ti_{2} O_{7} . Heat capacity and time-of-flight neutron scattering studies of single crystals reveal unconventional low-energy states. Er^{3+} magnetic ions reside on a pyrochlore lattice in Er_{2} Ti_{2} O_{7} ,...
[Phys. Rev. Lett. 101, 147205] Published Thu Oct 02, 2008
- Simple Glass Models and Their Quantum Annealing
Author(s): Thomas Jörg, Florent Krzakala, Jorge Kurchan, and A. C. Maggs
We study first-order quantum phase transitions in mean-field spin glasses. We solve the quantum random energy model using elementary methods and show that at the transition the eigenstate suddenly projects onto the unperturbed ground state and that the gap between the lowest states is exponentially ...
[Phys. Rev. Lett. 101, 147204] Published Thu Oct 02, 2008
- Direct Observation of Quantum Coherence in Single-Molecule Magnets
Author(s): C. Schlegel, J. van Slageren, M. Manoli, E. K. Brechin, and M. Dressel
Direct evidence of quantum coherence in a single-molecule magnet in a frozen solution is reported with coherence times as long as T_{2} =630±30 ns. We can strongly increase the coherence time by modifying the matrix in which the single-molecule magnets are embedded. The electron spins are coup...
[Phys. Rev. Lett. 101, 147203] Published Thu Oct 02, 2008
- Momentum Dependence of the Superconducting Gap in NdFeAsO_{0.9} F_{0.1} Single Crystals Measured by Angle Resolved Photoemission Spectroscopy
Author(s): Takeshi Kondo, A. F. Santander-Syro, O. Copie, Chang Liu, M. E. Tillman, E. D. Mun, J. Schmalian, S. L. Bud’ko, M. A. Tanatar, P. C. Canfield, and A. Kaminski
We use angle resolved photoemission spectroscopy to study the momentum dependence of the superconducting gap in NdFeAsO_{0.9} F_{0.1} single crystals. We find that the Γ hole pocket is fully gapped below the superconducting transition temperature. The value of the superconducting gap is 15±1.5 â...
[Phys. Rev. Lett. 101, 147003] Published Thu Oct 02, 2008
- Charge Frustration and Quantum Criticality for Strongly Correlated Fermions
Author(s): Liza Huijse, James Halverson, Paul Fendley, and Kareljan Schoutens
We study a model of strongly correlated electrons on the square lattice which exhibits charge frustration and quantum critical behavior. The potential is tuned to make the interactions supersymmetric. We establish a rigorous mathematical result which relates quantum ground states to certain tiling c...
[Phys. Rev. Lett. 101, 146406] Published Thu Oct 02, 2008
- Dependence of Effective Mass on Spin and Valley Degrees of Freedom
Author(s): T. Gokmen, Medini Padmanabhan, and M. Shayegan
We measure the effective mass (m^{*} ) of interacting two-dimensional electrons confined to an AlAs quantum well while we change the conduction-band valley occupation and the spin polarization via the application of strain and magnetic field, respectively. Compared to its band value, m^{*} is enhanc...
[Phys. Rev. Lett. 101, 146405] Published Thu Oct 02, 2008
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