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  • Characterization of mechanical unfolding intermediates of membrane proteins by coarse grained molecular dynamics simulation
    Chem. Phys. Lett. (IF 1.815) Pub Date : 2017-11-20
    Tatsuya Yamada, Shigeki Mitaku, Takahisa Yamato

    Single-molecule force spectroscopy by atomic force microscopy allows us to get insight into the mechanical unfolding of membrane proteins, and a typical experiment exhibits characteristic patterns on the force distance curves. The origin of these patterns, however, has not been fully understood yet. We performed coarse-grained simulation of the forced unfolding of halorodopsin, reproduced the characteristic features of the experimental force distance curves. A further examination near the membrane-water interface indicated the existence of a motif for the force peak formation, i.e., the occurrence of hydrophobic residues in the upper interface region and hydrophilic residues below the lower interface region.

    更新日期:2017-11-20
  • Structural and Electronic Properties of M-MOF-74 (M=Mg, Co or Mn)
    Chem. Phys. Lett. (IF 1.815) Pub Date : 2017-11-20
    Aline de Oliveira, Guilherme Ferreira de Lima, Heitor Avelino De Abreu

    The Metal-Organic Frameworks M-MOF-74 (M=Mg, Co or Mn) were investigated through Density Functional Theory calculations. Structural parameters and band gap energies were determined in agreement with experimental data, with errors under 2%. The methods Electron Localization Function and Quantum Theory of Atoms in Molecules were applied to the analyses of the electronic density topology of the three solids. These methodologies indicated that the bonds between the metallic cations and the oxygen atoms are predominantly ionic while the other ones are predominantly covalent. Furthermore, non-conventional hydrogen bonds were identified to Mg-MOF-74 and Co-MOF-74, which were not observed to Mn-MOF-74.

    更新日期:2017-11-20
  • Kinetics Studies of the F + HCl → HF + Cl Reaction on an Accurate Potential Energy Surface
    Chem. Phys. Lett. (IF 1.815) Pub Date : 2017-11-20
    Dandan Lu, Ying Zhang, Jun Li

    A full-dimensional electronic ground state potential energy surface for the hydrogen abstraction reaction F + HCl → HF + Cl is developed by using the permutation invariant polynomial neural network approach based on 6509 points computed at the level of CCSD(T)-F12a/AVTZ. Spin-orbit correction is also taken into account at the complete active space self-consistent field level. Theoretical thermal rate coefficients determined by the ring polymer molecular dynamics (RPMD) approach agree well with experiment, validating the accuracy of the PES. Kinetic isotope effect is also investigated.

    更新日期:2017-11-20
  • Nanoparticle formation by laser ablation of perylene microcrystals in an aqueous solution of Triton X-100
    Chem. Phys. Lett. (IF 1.815) Pub Date : 2017-11-20
    Kosuke Kimura, Mikako Gibo, Chikashi Merome, Teppei Kura, Sayuri Ooshiro, Yoshiaki Tamaki

    Perylene microcrystals in aqueous solutions containing various concentration of Triton X-100, nonionic surfactant, were irradiated by a nanosecond laser under various irradiation conditions including the fluence and length of irradiation time. Perylene nanoparticles with diameters of several hundred nm were formed by the laser irradiation only when Triton X-100 was added in the solutions at sufficiently high concentrations of the surfactant. The transfer of perylene molecules into the micelles of Triton X-100 was avoided by optimizing the concentrations of the surfactant so that only perylene nanoparticles were obtained in the aqueous solutions.

    更新日期:2017-11-20
  • Adsorption, Intercalation and Sensing of Helium on Yttrium Functionalized Open Edge Boron Nitride: A First principle DFT and TDDFT Study
    Chem. Phys. Lett. (IF 1.815) Pub Date : 2017-11-16
    Avat (Arman) Taherpour, Zahra Shahri, Omid Rezaei, Morteza Jamshidi, Thomas Fellowes

    Open edge BN boron-nitride has a stable graphene-like structure, which could be doped by a range of impurities, so the band gap could be tuned. The optical, electrical, physicochemical properties, NBO and electron density of open edge BN that is doped by Yttrium was evaluated using DFT method as a sensor for He gas. Here, was applied HSE1PBE method exchange correlation and LANL2DZ. The density of states and natural bond orbital analysis calculated have depicted that the band gap of BN-Y flake after sensing He gas and it has shown change from 1.66→2.42eV. The UV-Vis absorption in λmax area showed a significant red-shift that it is an appropriate parameter to recognize He molecule.

    更新日期:2017-11-20
  • Rapid Quantitative Measurements of Paramagnetic Relaxation Enhancements in Cu(II)-Tagged Proteins by Proton-Detected Solid-State NMR Spectroscopy
    J. Phys. Chem. Lett. (IF 9.353) Pub Date : 2017-11-20
    Dwaipayan Mukhopadhyay, Philippe S. Nadaud, Matthew D. Shannon, Christopher P. Jaroniec
    更新日期:2017-11-20
  • Theoretical Design on a Series of Novel Bicyclic and Cage Nitramines as High Energy Density Compounds
    J. Phys. Chem. A (IF 2.847) Pub Date : 2017-11-20
    Yong Pan, Weihua Zhu
    更新日期:2017-11-20
  • Comparison of Biomolecular Force Fields for Alkanethiol Self-Assembled Monolayer Simulations
    J. Phys. Chem. C (IF 4.536) Pub Date : 2017-11-20
    Pratiti Bhadra, Shirley W. I. Siu
    更新日期:2017-11-20
  • Characterization of Platinum Electrode Surfaces by Electrochemical Surface Forces Measurement
    J. Phys. Chem. C (IF 4.536) Pub Date : 2017-11-20
    Sho Fujii, Motohiro Kasuya, Kazue Kurihara
    更新日期:2017-11-20
  • Lifting the Spectral Crosstalk in Multifluorophore Assemblies
    J. Phys. Chem. C (IF 4.536) Pub Date : 2017-11-20
    Pavel Moroz, William P. Klein, Kiernan Akers, Abigail Vore, Natalia Kholmicheva, Natalia Razgoniaeva, Dmitriy Khon, Sebastián A. Díaz, Igor L. Medintz, Mikhail Zamkov
    更新日期:2017-11-20
  • Gas Phase Chemistry of Trimethylboron in Thermal Chemical Vapor Deposition
    J. Phys. Chem. C (IF 4.536) Pub Date : 2017-11-20
    Mewlude Imam, Laurent Souqui, Jan Herritsch, Andreas Stegmüller, Carina Höglund, Susann Schmidt, Richard Hall-Wilton, Hans Högberg, Jens Birch, Ralf Tonner, Henrik Pedersen
    更新日期:2017-11-20
  • Effect of Temperature on the Organization of Acetonitrile at the Silica/Liquid Interface
    J. Phys. Chem. C (IF 4.536) Pub Date : 2017-11-20
    Amanda J. Souna, Tylar L. Clark, John T. Fourkas
    更新日期:2017-11-20
  • Unraveling the Formation Mechanism of Dendritic Fibrous Nanosilica
    Langmuir (IF 3.833) Pub Date : 2017-11-20
    Ayan Maity, Avik Das, Debasis Sen, Subhasish Mazumder, Vivek Polshettiwar
    更新日期:2017-11-20
  • Aerogels from Chloromethyltrimethoxysilane and Their Functionalizations
    Langmuir (IF 3.833) Pub Date : 2017-11-20
    Tomoki Kimura, Taiyo Shimizu, Kazuyoshi Kanamori, Ayaka Maeno, Hironori Kaji, Kazuki Nakanishi
    更新日期:2017-11-20
  • 更新日期:2017-11-20
  • Characterization of topological phases of dimerized Kitaev chain via edge correlation functions
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Yucheng Wang, Jian-Jian Miao, Hui-Ke Jin, and Shu Chen

    We study analytically topological properties of a noninteracting modified dimerized Kitaev chain and an exactly solvable interacting dimerized Kitaev chain under open boundary conditions by analyzing two introduced edge correlation functions. The interacting dimerized Kitaev chain at the symmetry point Δ = t and the chemical potential μ = 0 can be exactly solved by applying two Jordan-Wigner transformations and a spin rotation, which permits us to calculate the edge correlation functions analytically. We demonstrate that the two edge correlation functions can be used to characterize the trivial, Su-Schrieffer-Heeger-like topological and topological superconductor phases of both the noninteracting and interacting systems and give their phase diagrams.

    更新日期:2017-11-20
  • Single layers and multilayers of GaN and AlN in square-octagon structure: Stability, electronic properties, and functionalization
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    E. Gürbüz, S. Cahangirov, E. Durgun, and S. Ciraci

    Further to planar single-layer hexagonal structures, GaN and AlN can also form free-standing, single-layer structures constructed from squares and octagons. We performed an extensive analysis of dynamical and thermal stability of these structures in terms of ab initio finite-temperature molecular dynamics and phonon calculations together with the analysis of Raman and infrared active modes. These single-layer square-octagon structures of GaN and AlN display directional mechanical properties and have wide, indirect fundamental band gaps, which are smaller than their hexagonal counterparts. These density functional theory band gaps, however, increase and become wider upon correction. Under uniaxial and biaxial tensile strain, the fundamental band gaps decrease and can be closed. The electronic and magnetic properties of these single-layer structures can be modified by adsorption of various adatoms, or by creating neutral cation-anion vacancies. The single-layer structures attain magnetic moment by selected adatoms and neutral vacancies. In particular, localized gap states are strongly dependent on the type of vacancy. The energetics, binding, and resulting electronic structure of bilayer, trilayer, and three-dimensional (3D) layered structures constructed by stacking the single layers are affected by vertical chemical bonds between adjacent layers. In addition to van der Waals interaction, these weak vertical bonds induce buckling in planar geometry and enhance their binding, leading to the formation of stable 3D layered structures. In this respect, these multilayers are intermediate between van der Waals solids and wurtzite crystals, offering a wide range of tunability.

    更新日期:2017-11-20
  • Open-boundary reflection of quantum well states at Pb(111)
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    M. Müller, N. Néel, S. Crampin, and J. Kröger

    Using a scanning tunneling microscope, confined electron states are studied that exist above subsurface nanometer-sized voids at Pb(111), where potential barriers at the parallel vacuum-Pb(111) and Pb(111)-void interfaces establish a principal series of quantum well states that are further confined laterally by strong reflection at the open boundaries at the edges of the void. The influence of the size, depth, and shape of the voids on the effectiveness of the lateral confinement is discussed. Standing wave patterns observed in differential conductance maps unravel the dispersion of the relevant underlying Pb electron states.

    更新日期:2017-11-20
  • Spin-charge conversion in disordered two-dimensional electron gases lacking inversion symmetry
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Chunli Huang, Mirco Milletarì, and Miguel A. Cazalilla

    We study the spin-charge conversion mechanisms in a two-dimensional gas of electrons moving in a smooth disorder potential by accounting for both Rashba-type and Mott's skew scattering contributions. We find that the quantum interference effects between spin-flip and skew scattering give rise to anisotropic spin precession scattering (ASP), a direct spin-charge conversion mechanism that was discovered in an earlier study of graphene decorated with adatoms [Huang et al., Phys. Rev. B 94, 085414 (2016)]. Our findings suggest that, together with other spin-charge conversion mechanisms such as the inverse galvanic effect, ASP is a fairly universal phenomenon that should be present in disordered two-dimensional systems lacking inversion symmetry.

    更新日期:2017-11-20
  • Spin-polarized ballistic conduction through correlated Au-NiMnSb-Au heterostructures
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    C. Morari, W. H. Appelt, A. Östlin, A. Prinz-Zwick, U. Schwingenschlögl, U. Eckern, and L. Chioncel

    We examine the ballistic conduction through Au-NiMnSb-Au heterostructures consisting of up to four units of the half-metallic NiMnSb in the scattering region, using density functional theory (DFT) methods. For a single NiMnSb unit the transmission function displays a spin polarization of around 50 % in a window of 1 eV centered around the Fermi level. By increasing the number of layers, an almost complete spin polarization of the transmission is obtained in this energy range. Supplementing the DFT calculations with local electronic interactions, of Hubbard-type on the Mn sites, leads to a hybridization between the interface and many-body states. The significant reduction of the spin polarization seen in the density of states is not apparent in the spin polarization of the conduction electron transmission, which suggests that the hybridized interface and many-body induced states are localized.

    更新日期:2017-11-20
  • Optical conductivity of a two-dimensional metal near a quantum critical point: The status of the extended Drude formula
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Andrey V. Chubukov and Dmitrii L. Maslov
    更新日期:2017-11-20
  • Spin-orbit coupling, optical transitions, and spin pumping in monolayer and few-layer InSe
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    S. J. Magorrian, V. Zólyomi, and V. I. Fal'ko

    We show that spin-orbit coupling (SOC) in InSe enables the optical transition across the principal band gap to couple with in-plane polarized light. This transition, enabled by p x , y ↔ p z hybridization due to intra-atomic SOC in both In and Se, can be viewed as a transition between two dominantly s - and p z -orbital based bands, accompanied by an electron spin-flip. Having parametrized k · p theory using first-principles density functional theory we estimate the absorption for σ ± circularly polarized photons in the monolayer as ∼ 1.5 %, which saturates to ∼ 0.3 % in thicker films (3–5 layers). Circularly polarized light can be used to selectively excite electrons into spin-polarized states in the conduction band, which permits optical pumping of the spin polarization of In nuclei through the hyperfine interaction.

    更新日期:2017-11-20
  • Chemically exfoliatedMoS2layers: Spectroscopic evidence for the semiconducting nature of the dominant trigonal metastable phase
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Banabir Pal, Anjali Singh, Sharada G., Pratibha Mahale, Abhinav Kumar, S. Thirupathaiah, H. Sezen, M. Amati, Luca Gregoratti, Umesh V. Waghmare, and D. D. Sarma

    A metastable trigonal phase, existing only as small patches on a chemically exfoliated few-layered, thermodynamically stable 1 H phase of Mo S 2 , is believed to critically influence the properties of Mo S 2 -based devices. The electronic structure of this metastable phase is little understood in the absence of a direct experimental investigation of its electronic properties, complicated further by conflicting claims from theoretical investigations. We address this issue by investigating the electronic structure of this minority phase in chemically exfoliated Mo S 2 few-layered systems by enhancing its contributions with the use of highly spatially resolved ( ≤ 120 nm resolution) photoemission spectroscopy and Raman spectroscopy in conjunction with state-of-the-art electronic structure calculations. Based on these results, we establish that the ground state of this phase, arrived at by the chemical exfoliation of Mo S 2 using the usual Li intercalation technique, is a small gap ( ∼ 90 ± 40 meV ) semiconductor in contrast to most claims in the literature; we also identify the specific trigonal structure it has among many suggested ones.

    更新日期:2017-11-20
  • Anisotropic pseudopotential characterization of quantum Hall systems under a tilted magnetic field
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Bo Yang, Ching Hua Lee, Chi Zhang, and Zi-Xiang Hu

    We analytically derived the effective two-body interaction for a finite thickness quantum Hall system with a harmonic perpendicular confinement and an in-plane magnetic field. The anisotropic effective interaction in the lowest Landau level (LLL) and first Landau level (1LL) are expanded in the basis of the generalized pseudopotentials (PPs), and we analyze how the coefficients of some prominent isotropic and anisotropic PPs depend on the thickness of the sample and the strength of the in-plane magnetic field. We also investigate the stability of the topological quantum Hall states, especially the Laughlin state and its emergent guiding center metric, which we can now compute analytically. An interesting reorientation of the anisotropy direction of the Laughlin state in the 1LL is revealed, and we also discuss various possible experimental ramifications for this quantum Hall system with broken rotational symmetry.

    更新日期:2017-11-20
  • Quantum field theory of X-cube fracton topological order and robust degeneracy from geometry
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Kevin Slagle and Yong Baek Kim

    We propose a quantum field theory description of the X-cube model of fracton topological order. The field theory is not (and cannot be) a topological quantum field theory (TQFT) since, unlike the X-cube model, TQFTs are invariant (i.e., symmetric) under continuous space-time transformations. However, the theory is instead invariant under a certain subgroup of the conformal group. We describe how braiding statistics and ground-state degeneracy are reproduced by the field theory, and how the the X-cube Hamiltonian and field theory can be minimally coupled to matter fields. We also show that even on a manifold with trivial topology, spatial curvature can induce a ground-state degeneracy that is stable to arbitrary local perturbations! Our formalism may allow for the description of other fracton field theories, where the only necessary input is an equation of motion for a charge density.

    更新日期:2017-11-20
  • Principal component analysis for fermionic critical points
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Natanael C. Costa, Wenjian Hu, Z. J. Bai, Richard T. Scalettar, and Rajiv R. P. Singh

    We use determinant quantum Monte Carlo (DQMC), in combination with the principal component analysis (PCA) approach to unsupervised learning, to extract information about phase transitions in several of the most fundamental Hamiltonians describing strongly correlated materials. We first explore the zero-temperature antiferromagnet to singlet transition in the periodic Anderson model, the Mott insulating transition in the Hubbard model on a honeycomb lattice, and the magnetic transition in the 1/6-filled Lieb lattice. We then discuss the prospects for learning finite temperature superconducting transitions in the attractive Hubbard model, for which there is no sign problem. Finally, we investigate finite temperature charge density wave (CDW) transitions in the Holstein model, where the electrons are coupled to phonon degrees of freedom, and carry out a finite size scaling analysis to determine T c . We examine the different behaviors associated with Hubbard-Stratonovich auxiliary field configurations on both the entire space-time lattice and on a single imaginary time slice, or other quantities, such as equal-time Green's and pair-pair correlation functions.

    更新日期:2017-11-20
  • High-pressure versus isoelectronic doping effect on the honeycomb iridateNa2IrO3
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    V. Hermann, J. Ebad-Allah, F. Freund, I. M. Pietsch, A. Jesche, A. A. Tsirlin, J. Deisenhofer, M. Hanfland, P. Gegenwart, and C. A. Kuntscher

    We study the effect of isoelectronic doping and external pressure in tuning the ground state of the honeycomb iridate Na 2 IrO 3 by combining optical spectroscopy with synchrotron x-ray diffraction measurements on single crystals. The obtained optical conductivity of Na 2 IrO 3 is discussed in terms of a Mott-insulating picture versus the formation of quasimolecular orbitals and in terms of Kitaev interactions. With increasing Li content  x , ( Na 1 − x Li x ) 2 IrO 3 moves deeper into the Mott-insulating regime, and there are indications that up to a doping level of 24% the compound comes closer to the Kitaev limit. The optical conductivity spectrum of single-crystalline α − Li 2 IrO 3 does not follow the trends observed for the series up to x = 0.24 . There are strong indications that α − Li 2 IrO 3 is not as close to the Kitaev limit as Na 2 IrO 3 and lies closer to the quasimolecular orbital picture instead. Except for the pressure-induced hardening of the phonon modes, the optical properties of Na 2 IrO 3 seem to be robust against external pressure. Possible explanations of the unexpected evolution of the optical conductivity with isolectronic doping and the drastic change between x = 0.24 and x = 1 are given by comparing the pressure-induced changes of lattice parameters and the optical conductivity with the corresponding changes induced by doping.

    更新日期:2017-11-20
  • Entanglement spectroscopy on a quantum computer
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Sonika Johri, Damian S. Steiger, and Matthias Troyer
    更新日期:2017-11-20
  • Amplitude mode oscillations in pump-probe photoemission spectra from ad-wave superconductor
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    B. Nosarzewski, B. Moritz, J. K. Freericks, A. F. Kemper, and T. P. Devereaux

    Recent developments in the techniques of ultrafast pump-probe photoemission have made possible the search for collective modes in strongly correlated systems out of equilibrium. Including inelastic scattering processes and a retarded interaction, we simulate time- and angle-resolved photoemission spectroscopy (trARPES) to study the amplitude mode of a d -wave superconductor, a collective mode excited through the nonlinear light-matter coupling to the pump pulse. We find that the amplitude mode oscillations of the d -wave order parameter occur in phase at a single frequency that is twice the quasi-steady-state maximum gap size after pumping. We comment on the necessary conditions for detecting the amplitude mode in trARPES experiments.

    更新日期:2017-11-20
  • Magnetic solitons and magnetic phase diagram of the hexagonal chiral crystalCrNb3S6in oblique magnetic fields
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Jun-ichiro Yonemura, Yusuke Shimamoto, Takanori Kida, Daichi Yoshizawa, Yusuke Kousaka, Sadafumi Nishihara, Francisco Jose Trindade Goncalves, Jun Akimitsu, Katsuya Inoue, Masayuki Hagiwara, and Yoshihiko Togawa

    We investigate the magnetic torque and magnetoresistance (MR) responses in oblique magnetic fields in micrometer-sized specimens of the hexagonal chiral magnetic crystal CrNb 3 S 6 . The results exhibit hysteresis over a wide range of applied field angles, while reversible behavior appears only when the magnetic field is closely aligned to the helical axis of the crystal. Stepwise changes of the magnetic torque and MR detected in the hysteresis region indicate the existence of chiral solitons in the oblique magnetic fields. A magnetic phase diagram is derived from the experimental results, and the stability of the chiral magnetic phases, such as the chiral soliton lattice and chiral conical phase, and the nature of the phase transition between them are discussed.

    更新日期:2017-11-20
  • Magnetic-field-induced decrease of the spin Peltier effect inPt/Y3Fe5O12system at room temperature
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    Ryuichi Itoh, Ryo Iguchi, Shunsuke Daimon, Koichi Oyanagi, Ken-ichi Uchida, and Eiji Saitoh

    We report the observation of magnetic-field-induced decrease of the spin Peltier effect (SPE) in a junction of a paramagnetic metal Pt and a ferrimagnetic insulator Y 3 Fe 5 O 12 (YIG) at room temperature. For driving the SPE, spin currents are generated via the spin Hall effect from applied charge currents in the Pt layer, and injected into the adjacent thick YIG film. The resultant temperature modulation is detected by a commonly used thermocouple attached to the Pt/YIG junction. The output of the thermocouple shows sign reversal when the magnetization is reversed and linearly increases with the applied current, demonstrating the detection of the SPE signal. We found that the SPE signal decreases with the magnetic field. The observed decreasing rate was found to be comparable to that of the spin Seebeck effect (SSE), suggesting the dominant and similar contribution of the low-energy magnons in the SPE as in the SSE.

    更新日期:2017-11-20
  • Coupling of structure to magnetic and superconducting orders in quasi-one-dimensionalK2Cr3As3
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    K. M. Taddei, Q. Zheng, A. S. Sefat, and C. de la Cruz

    Quasi-one-dimensional A 2 Cr 3 As 3 (with A = K , Cs, Rb) is an intriguing new family of superconductors which exhibit many similar features to the cuprate and iron-based unconventional superconductor families. Yet, in contrast to these systems, no charge or magnetic ordering has been observed which could provide the electronic correlations presumed necessary for an unconventional superconducting pairing mechanism—an absence which defies predictions of first-principles models. We report the results of neutron scattering experiments on polycrystalline K 2 Cr 3 As 3 ( T c ∼ 7 K ) which probed the low-temperature dynamics near T c . Neutron diffraction data evidence a subtle response of the nuclear lattice to the onset of superconductivity while inelastic scattering reveals a highly dispersive column of intensity at the commensurate wave vector q = 00 1 2 which loses intensity beneath T c —indicative of short-range magnetic fluctuations. Using linear spin-wave theory, we model the observed scattering and suggest a possible structure to the short-range magnetic order. These observations suggest that K 2 Cr 3 As 3 is in close proximity to a magnetic instability and that the incipient magnetic order both couples strongly to the lattice and competes with superconductivity, in direct analogy with the iron-based superconductors.

    更新日期:2017-11-20
  • Doping-induced quantum crossover inEr2Ti2−xSnxO7
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    M. Shirai, R. S. Freitas, J. Lago, S. T. Bramwell, C. Ritter, and I. Živković

    We present the results of the investigation of magnetic properties of the Er 2 Ti 2 − x Sn x O 7 series. For small doping values, the ordering temperature decreases linearly with x , while the moment configuration remains the same as in the x = 0 parent compound. Around x = 1.7 doping level, we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time, we present evidence of a long-range order (LRO) in Er 2 Sn 2 O 7 ( x = 2.0 ) below T N = 130 mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to x = 0 . We discuss our results in the framework of a possible quantum phase transition occurring close to x = 1.7 .

    更新日期:2017-11-20
  • Determining the vortex tilt relative to a superconductor surface
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    V. G. Kogan and J. R. Kirtley

    It is of interest to determine the exit angle of a vortex from a superconductor surface, since this affects the intervortex interactions and their consequences. Two ways to determine this angle are to image the vortex magnetic fields above the surface, or the vortex core shape at the surface. In this work we evaluate the field h ( x , y , z ) above a flat superconducting surface x , y and the currents J ( x , y ) at that surface for a straight vortex tilted relative to the normal to the surface, for both the isotropic and anisotropic cases. In principle, these results can be used to determine the vortex exit tilt angle from analyses of magnetic field imaging or density of states data.

    更新日期:2017-11-20
  • Unconventional superconductivity and an ambient-pressure magnetic quantum critical point in single-crystalLaNiC2
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    J. F. Landaeta, D. Subero, P. Machado, F. Honda, and I. Bonalde

    Superconductivity in noncentrosymmetric LaNiC 2 is expected to be induced by electron-phonon interactions due to its lack of magnetic instabilities. The non-Bardeen-Cooper-Schrieffer (BCS) behaviors found in this material call into question the long-standing idea that relates unconventional superconductivity with magnetic interactions. Here we report magnetic penetration-depth measurements in a high-purity single crystal of LaNiC 2 at pressures up to 2.5 GPa and temperatures down to 0.04 K. At ambient pressure and below 0.5 T c the penetration depth goes as T 4 for the in-plane and T 2 for the out-of-plane component, firmly implying the existence of point nodes in the energy gap and the unconventional character of this superconductor. The present study also provides evidence of magnetism in LaNiC 2 by unraveling a pressure-induced antiferromagnetic phase inside the superconducting state at temperatures below 0.5 K, with a quantum critical point around ambient pressure. The results presented here maintain a solid base for the notion that unconventional superconductivity only arises near magnetic order or fluctuations.

    更新日期:2017-11-20
  • Thickness and angular dependence of the magnetocurrent of hot electrons in a magnetic tunnel transistor with crossed anisotropies
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    C. Vautrin, D. Lacour, G. Sala, Y. Lu, F. Montaigne, and M. Hehn

    We have studied the thickness and angular dependence of the magnetocurrent of hot electrons in a magnetic tunnel transistor (MTT) with crossed magnetic anisotropies. In a first step, we show that the magnetocurrent increases with ferromagnetic layer thickness as for MTTs with collinear magnetic configurations. The maximum magnetocurrent value is obtained to be 85%, which is close to the theoretical maximum value of 100% for MTTs with crossed magnetic configurations. In a second step, we demonstrate that we are able to reproduce both current vs field direction and current vs field intensity measurements in a framework taking into account a reduced number of magnetic parameters and a simple cosine dependence of the hot-electron current on the angle between magnetizations.

    更新日期:2017-11-20
  • Magnetization, specific heat, and thermal conductivity of hexagonalErMnO3single crystals
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    J. D. Song, C. Fan, Z. Y. Zhao, F. B. Zhang, J. Y. Zhao, X. G. Liu, X. Zhao, Y. J. Liu, J. F. Wang, and X. F. Sun

    We report a study of magnetism and magnetic transitions of hexagonal ErMnO 3 single crystals by magnetization, specific heat, and heat transport measurements. Magnetization data show that the c -axis magnetic field induces three magnetic transitions at 0.8, 12, and 28 T. The specific heat shows a peak at 2.2 K, which is due to a magnetic transition of Er 3 + moments. For low- T thermal conductivity ( κ ) , a clear diplike feature appears in the κ ( H ) isotherm at 1–1.25 T for H ∥ a b , while in the case of H ∥ c , a steplike increase is observed at 0.5–0.8 T. The transition fields in κ ( H ) are in good agreement with those obtained from magnetization, and the anomaly of κ can be understood by a spin-phonon scattering scenario. The natures of magnetic structures and corresponding field-induced transitions at low temperatures are discussed.

    更新日期:2017-11-20
  • Spin excitations and quantum criticality in the quasi-one-dimensional Ising-like ferromagnetCoCl2·2D2Oin a transverse field
    Phys. Rev. B (IF 3.836) Pub Date : 2017-11-20
    J. Larsen, T. K. Schäffer, U. B. Hansen, S. L. Holm, S. R. Ahl, R. Toft-Petersen, J. Taylor, G. Ehlers, J. Jensen, H. M. Rønnow, K. Lefmann, and N. B. Christensen

    We present experimental evidence for a quantum phase transition in the easy-axis S = 3 / 2 anisotropic quasi-one-dimensional ferromagnet CoCl 2 · 2 D 2 O in a transverse field. Elastic neutron scattering shows that the magnetic order parameter vanishes at a transverse critical field μ 0 H c = 16.05 (4) T, while inelastic neutron scattering shows that the gap in the magnetic excitation spectrum vanishes at the same field value, and reopens for H > H c . The field dependence of the order parameter and the gap are well described by critical exponents β = 0.45 ± 0.09 and z ν close to 1 / 2 , implying that the quantum phase transition in CoCl 2 · 2 D 2 O differs significantly from the textbook version of a S = 1 / 2 Ising chain in a transverse field. We attribute the difference to weak but finite three-dimensionality of the magnetic interactions.

    更新日期:2017-11-20
  • Highly efficient gas-phase reactivity of protonated pyridine radicals with propene
    Phys. Chem. Chem. Phys. (IF 4.123) Pub Date : 2017-11-13
    Cameron C. Bright, Matthew B. Prendergast, Patrick D. Kelly, James P. Bezzina, Stephen J. Blanksby, Gabriel da Silva, Adam J. Trevitt
    更新日期:2017-11-20
  • Direct estimation of the transfer integral for photoinduced electron transfer from TD DFT calculations
    Phys. Chem. Chem. Phys. (IF 4.123) Pub Date : 2017-11-10
    Lluís Blancafort, Alexander A. Voityuk
    更新日期:2017-11-20
  • Charge doping in graphene on thermodynamically preferred BiFeO3(0001) polar surfaces
    Phys. Chem. Chem. Phys. (IF 4.123) Pub Date : 2017-11-09
    Jian-Qing Dai, Xiao-Ya Li, Jie-Wang Xu
    更新日期:2017-11-20
  • Conformational collapse of spherical poly(N-isopropylacrylamide) brushes under the constraint of bound micelles
    Phys. Chem. Chem. Phys. (IF 4.123) Pub Date : 2017-11-06
    Peng-Wei Zhu, Luguang Chen
    更新日期:2017-11-20
  • Erratum: Resonance Effects in Photoemission Time Delays [Phys. Rev. Lett.115, 133001 (2015)]
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    M. Sabbar, S. Heuser, R. Boge, M. Lucchini, T. Carette, E. Lindroth, L. Gallmann, C. Cirelli, and U. Keller

    DOI:https://doi.org/10.1103/PhysRevLett.119.219901

    更新日期:2017-11-20
  • Z3Parafermionic Zero Modes without Andreev Backscattering from the2/3Fractional Quantum Hall State
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Yahya Alavirad, David Clarke, Amit Nag, and Jay D. Sau

    Parafermionic zero modes are a novel set of excitations displaying non-Abelian statistics somewhat richer than that of Majorana modes. These modes are predicted to occur when nearby fractional quantum Hall edge states are gapped by an interposed superconductor. Despite substantial experimental progress, we argue that the necessary crossed Andreev reflection in this arrangement is a challenging milestone to reach. We propose a superconducting quantum dot array structure on a fractional quantum Hall edge that can lead to parafermionic zero modes from coherent superconducting forward scattering on a quantum Hall edge. Such coherent forward scattering has already been demonstrated in recent experiments. We show that for a spin-singlet superconductor interacting with loops of spin unpolarized 2 / 3 fractional quantum edge, even an array size of order 10 should allow one to systematically tune into a parafermionic degeneracy.

    更新日期:2017-11-20
  • Thermodynamic Evidence for the Fulde-Ferrell-Larkin-Ovchinnikov State in theKFe2As2Superconductor
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Chang-woo Cho, Jonathan Haiwei Yang, Noah F. Q. Yuan, Junying Shen, Thomas Wolf, and Rolf Lortz

    We investigate the magnetic phase diagram near the upper critical field of KFe 2 As 2 by magnetic torque and specific heat experiments using a high-resolution piezorotary positioner to precisely control the parallel alignment of the magnetic field with respect to the FeAs layers. We observe a clear double transition when the field is strictly aligned in the plane and a characteristic upturn of the upper critical field line, which goes far beyond the Pauli limit at 4.8 T. This provides firm evidence that a Fulde-Ferrell-Larkin-Ovchinnikov state exists in this iron-based KFe 2 As 2 superconductor.

    更新日期:2017-11-20
  • Observation of Bogoliubov Band Hybridization in the Optimally Doped TrilayerBi2Sr2Ca2Cu3O10+δ
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    So Kunisada, Shintaro Adachi, Shiro Sakai, Nae Sasaki, Mitsuhiro Nakayama, Shuntaro Akebi, Kenta Kuroda, Takao Sasagawa, Takao Watanabe, Shik Shin, and Takeshi Kondo
    更新日期:2017-11-20
  • Correlated Three-Dimensional Imaging of Dislocations: Insights into the Onset of Thermal Slip in Semiconductor Wafers
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    D. Hänschke, A. Danilewsky, L. Helfen, E. Hamann, and T. Baumbach
    更新日期:2017-11-20
  • Instabilities of Jammed Packings of Frictionless Spheres Under Load
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Ning Xu, Andrea J. Liu, and Sidney R. Nagel

    We consider the contribution to the density of vibrational states and the distribution of energy barrier heights of incipient instabilities in a glass modeled by a jammed packing of spheres. On approaching an instability, the frequency of a normal mode and the height of the energy barrier to cross into a new ground state both vanish. These instabilities produce a contribution to the density of vibrational states that scales as ω 3 at low frequencies ω , and a contribution to the distribution of energy barriers Δ H that scales as Δ H − 1 / 3 at low barrier heights.

    更新日期:2017-11-20
  • Correlation between Local Structure Order and Spatial Heterogeneity in a Metallic Glass
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Fan Zhu, Akihiko Hirata, Pan Liu, Shuangxi Song, Yuan Tian, Jiuhui Han, Takeshi Fujita, and Mingwei Chen

    Although nanoscale spatial heterogeneity of metallic glasses has been demonstrated by extensive experimental and theoretical investigations, the nature of spatial heterogeneity remains poorly known owing to the absence of a structural depiction of the inhomogeneity from experimental insight. Here we report the experimental characterization of the spatial heterogeneity of a metallic glass by utilizing state-of-the-art angstrom-beam electron diffraction and scanning transmission electron microscopy. The subnanoscale electron diffraction reveals that the nanoscale spatial heterogeneity and corresponding density fluctuation have a close correlation with the local structure variation from icosahedronlike to tetragonal crystal-like order. The structural insights of spatial heterogeneity have important implications in understanding the properties and dynamics of metallic glasses.

    更新日期:2017-11-20
  • Superfluid Filaments of Dipolar Bosons in Free Space
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Fabio Cinti, Alberto Cappellaro, Luca Salasnich, and Tommaso Macrì

    We systematically investigate the zero temperature phase diagram of bosons interacting via dipolar interactions in three dimensions in free space via path integral Monte Carlo simulations with a few hundreds of particles and periodic boundary conditions based on the worm algorithm. Upon increasing the strength of the dipolar interaction and at sufficiently high densities we find a wide region where filaments are stabilized along the direction of the external field. Most interestingly by computing the superfluid fraction we conclude that the superfluidity is anisotropic and is greatly suppressed along the orthogonal plane. Finally, we perform simulations at finite temperature confirming the stability of the filaments against thermal fluctuations and provide an estimate of the superfluid fraction in the weak coupling limit in the framework of the Landau two-fluid model.

    更新日期:2017-11-20
  • Double Contact During Drop Impact on a Solid Under Reduced Air Pressure
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Er Qiang Li, Kenneth R. Langley, Yuan Si Tian, Peter D. Hicks, and Sigurdur T. Thoroddsen

    Drops impacting on solid surfaces entrap small bubbles under their centers, owing to the lubrication pressure which builds up in the thin intervening air layer. We use ultrahigh-speed interference imaging, at 5 Mfps, to investigate how this air layer changes when the ambient air pressure is reduced below atmospheric. Both the radius and the thickness of the air disc become smaller with reduced air pressure. Furthermore, we find the radial extent of the air disc bifurcates, when the compressibility parameter exceeds ∼ 25 . This bifurcation is also imprinted onto some of the impacts, as a double contact. In addition to the central air disc inside the first ring contact, this is immediately followed by a second ring contact, which entraps an outer toroidal strip of air, which contracts into a ring of bubbles. We find this occurs in a regime where Navier slip, due to rarefied gas effects, enhances the rate gas can escape from the path of the droplet.

    更新日期:2017-11-20
  • What Controls Thermo-osmosis? Molecular Simulations Show the Critical Role of Interfacial Hydrodynamics
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Li Fu, Samy Merabia, and Laurent Joly

    Thermo-osmotic and related thermophoretic phenomena can be found in many situations from biology to colloid science, but the underlying molecular mechanisms remain largely unexplored. Using molecular dynamics simulations, we measure the thermo-osmosis coefficient by both mechanocaloric and thermo-osmotic routes, for different solid-liquid interfacial energies. The simulations reveal, in particular, the crucial role of nanoscale interfacial hydrodynamics. For nonwetting surfaces, thermo-osmotic transport is largely amplified by hydrodynamic slip at the interface. For wetting surfaces, the position of the hydrodynamic shear plane plays a key role in determining the amplitude and sign of the thermo-osmosis coefficient. Finally, we measure a giant thermo-osmotic response of the water-graphene interface, which we relate to the very low interfacial friction displayed by this system. These results open new perspectives for the design of efficient functional interfaces for, e.g., waste-heat harvesting.

    更新日期:2017-11-20
  • Three Dimensional Photonic Dirac Points in Metamaterials
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Qinghua Guo, Biao Yang, Lingbo Xia, Wenlong Gao, Hongchao Liu, Jing Chen, Yuanjiang Xiang, and Shuang Zhang

    Topological semimetals, representing a new topological phase that lacks a full band gap in bulk states and exhibiting nontrivial topological orders, recently have been extended to photonic systems, predominantly in photonic crystals and to a lesser extent metamaterials. Photonic crystal realizations of Dirac degeneracies are protected by various space symmetries, where Bloch modes span the spin and orbital subspaces. Here, we theoretically show that Dirac points can also be realized in effective media through the intrinsic degrees of freedom in electromagnetism under electromagnetic duality. A pair of spin-polarized Fermi-arc-like surface states is observed at the interface between air and the Dirac metamaterials. Furthermore, eigenreflection fields show the decoupling process from a Dirac point to two Weyl points. We also find the topological correlation between a Dirac point and vortex or vector beams in classical photonics. The experimental feasibility of our scheme is demonstrated by designing a realistic metamaterial structure. The theoretical proposal of the photonic Dirac point lays the foundation for unveiling the connection between intrinsic physics and global topology in electromagnetism.

    更新日期:2017-11-20
  • Cavity QED Engineering of Spin Dynamics and Squeezing in a Spinor Gas
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Stuart J. Masson, M. D. Barrett, and Scott Parkins

    We propose a method for engineering spin dynamics in ensembles of integer-spin atoms confined within a high-finesse optical cavity. Our proposal uses cavity-assisted Raman transitions to engineer a Dicke model for integer-spin atoms, which, in a dispersive limit, reduces to effective atom-atom interactions within the ensemble. This scheme offers a promising and flexible new avenue for the exploration of a wide range of spinor many-body physics. As an example of this, we present results showing that this method can be used to generate spin-nematic squeezing in an ensemble of spin-1 atoms. With realistic parameters, the scheme should enable substantial squeezing on time scales much shorter than current experiments with spin-1 Bose-Einstein condensates.

    更新日期:2017-11-20
  • Threshold and Jet Radius Joint Resummation for Single-Inclusive Jet Production
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Xiaohui Liu, Sven-Olaf Moch, and Felix Ringer

    We present the first threshold and jet radius jointly resummed cross section for single-inclusive hadronic jet production. We work at next-to-leading logarithmic accuracy and our framework allows for a systematic extension beyond the currently achieved precision. Long-standing numerical issues are overcome by performing the resummation directly in momentum space within soft collinear effective theory. We present the first numerical results for the LHC and observe an improved description of the available data. Our results are of immediate relevance for LHC precision phenomenology including the extraction of parton distribution functions and the QCD strong coupling constant.

    更新日期:2017-11-20
  • Asymptotic Safety Guaranteed in Supersymmetry
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Andrew D. Bond and Daniel F. Litim

    We explain how asymptotic safety arises in four-dimensional supersymmetric gauge theories. We provide asymptotically safe supersymmetric gauge theories together with their superconformal fixed points, R charges, phase diagrams, and UV-IR connecting trajectories. Strict perturbative control is achieved in a Veneziano limit. Consistency with unitarity and the a theorem is established. We find that supersymmetry enhances the predictivity of asymptotically safe theories.

    更新日期:2017-11-20
  • Probing Sub-GeV Mass Strongly Interacting Dark Matter with a Low-Threshold Surface Experiment
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Jonathan H. Davis

    Using data from the ν -cleus detector, based on the surface of Earth, we place constraints on dark matter in the form of strongly interacting massive particles (SIMPs) which interact with nucleons via nuclear-scale cross sections. For large SIMP-nucleon cross sections, the sensitivity of traditional direct dark matter searches using underground experiments is limited by the energy loss experienced by SIMPs, due to scattering with the rock overburden and experimental shielding on their way to the detector apparatus. Hence, a surface-based experiment is ideal for a SIMP search, despite the much larger background resulting from the lack of shielding. We show using data from a recent surface run of a low-threshold cryogenic detector that values of the SIMP-nucleon cross section up to approximately 10 − 27     cm 2 can be excluded for SIMPs with masses above 100 MeV.

    更新日期:2017-11-20
  • Hořava Gravity is Asymptotically Free in2+1Dimensions
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    Andrei O. Barvinsky, Diego Blas, Mario Herrero-Valea, Sergey M. Sibiryakov, and Christian F. Steinwachs

    We compute the β functions of marginal couplings in projectable Hořava gravity in 2 + 1 spacetime dimensions. We show that the renormalization group flow has an asymptotically free fixed point in the ultraviolet (UV), establishing the theory as a UV-complete model with dynamical gravitational degrees of freedom. Therefore, this theory may serve as a toy model to study fundamental aspects of quantum gravity. Our results represent a step forward towards understanding the UV properties of realistic versions of Hořava gravity.

    更新日期:2017-11-20
  • Efficient Low-Order Approximation of First-Passage Time Distributions
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    David Schnoerr, Botond Cseke, Ramon Grima, and Guido Sanguinetti

    We consider the problem of computing first-passage time distributions for reaction processes modeled by master equations. We show that this generally intractable class of problems is equivalent to a sequential Bayesian inference problem for an auxiliary observation process. The solution can be approximated efficiently by solving a closed set of coupled ordinary differential equations (for the low-order moments of the process) whose size scales with the number of species. We apply it to an epidemic model and a trimerization process and show good agreement with stochastic simulations.

    更新日期:2017-11-20
  • Nonlocal Entanglement of 1D Thermal States Induced by Fermion Exchange Statistics
    Phys. Rev. Lett. (IF 8.462) Pub Date : 2017-11-20
    YeJe Park, Jeongmin Shim, S.-S. B. Lee, and H.-S. Sim

    When two identical fermions exchange their positions, their wave function gains a phase factor of − 1 . We show that this distance-independent effect can induce nonlocal entanglement in one-dimensional (1D) electron systems having Majorana fermions at the ends. It occurs in the system bulk and has a nontrivial temperature dependence. In a system having a single Majorana fermion at each end, the nonlocal entanglement has a Bell-state form at zero temperature and decays as the temperature increases, vanishing suddenly at a certain finite temperature. In a system having two Majorana fermions at each end, it is in a cluster-state form and its nonlocality is more noticeable at a finite temperature. By contrast, the thermal states of corresponding 1D spins do not have nonlocal entanglement.

    更新日期:2017-11-20
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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