journal

# Journal of Physics. Condensed Matter: An Institute of Physics Journal

journal
#1
Sebastiano Bernini, Francesco Puosi, Dino Leporini
We investigate by Molecular Dynamics simulations of a molecular liquid the thermodynamic scaling (TS) of the structural relaxation time $\tau_\alpha$ in terms of the quantity $T\rho^{-\gamma_{ts}}$ where T and rho are the temperature and the density, respectively. The liquid does not exhibit strong virial-energy correlations. We propose how to evaluate both the characteristic exponent $\gamma_{ts}$ and the TS master curve by resorting to experimentally accessible quantities characterising the anharmonic elasticity and no details about the microscopic interactions...
January 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#2
Shimin Cao, Jiaojiao Zhou, Xuan Wei, Shu-Guang Cheng
Massless charge carriers in gate potential modulate graphene quantum well transport in a same way that electromagnetic wave propagates in optical fibers. Recent experiment by Kim {\it et al} (Nat. Phys. 12 1022) reports the valley symmetry preserved transport in graphene carrier guider. Based on a tight-binding model, the valley resolved transport coefficients are calculated with the method of scattering matrix theory. For a straight potential well, valley resolved conductance is quantized with value $2n+1$ multiply $2e^2/h$ with integer $n$...
January 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#3
Hojjat Behmadi, Zahra Fazli, Ali Najafi
Taking into account both the Vicsek short range ordering and the far-field hydrodynamic interactions mediated by the ambient fluid, we investigate the role of long range interactions in the ordering phenomena in a quasi 2-dimensional active suspension. By studying the number fluctuations, the velocity correlation functions and cluster size distribution function, we show that depending on the number density of swimmers and the strength of noise, the hydrodynamic interactions can have significant effects in a suspension...
January 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#4
Cai Xiaoming
We study the competition of disorder and superconductivity for a generalized Kitaev model in incommensurate potentials. The generalized Kitaev model describes one dimensional spinless fermions with long-range p-wave superconducting pairing, which decays with distance <i>l</i> as a power law ���1/<i>l</i><sup>��</sup>. We focus on the transition from the topological superconducting phase to the topologically trivial Anderson localized phase, and effects of the exponent �� on this phase transition...
January 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#5
Kristina Pickl, Jayant Pande, Harald Köstler, Ulrich Rüde, Ana-Suncana Smith
Propulsion at low Reynolds numbers is often studied by defining artificial microswimmers which exhibit a particular stroke. The disadvantage of such an approach is that the stroke does not adjust to the environment, in particular the fluid flow, which can diminish the effect of hydrodynamic interactions. To overcome this limitation, we simulate a microswimmer consisting of three beads connected by springs and dampers, using the self-developed waLBerla and <i>pe</i> framework based on the lattice Boltzmann method and the discrete element method...
January 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#6
Kevin Rossi, Tom Ellaby, Lauro Oliver Paz Borbon, Ivailo Atanasov, Luca Pavan, Francesca Baletto
On the basis of ab-initio calculations, we present a new parametrisation of the Vervisch-Mottet-Goniakowski (VMG) potential [Vervisch et al. Phys. Rev B24, 245411 (2002)] for modelling the oxide-metal interaction. Applying this model to mimic the finite temperature behaviour of large platinum icosahedra deposited on the pristine MgO(100), we find the nanoparticle undergoes two solid-solid transitions. At 650 K the ���squarisation��� of the interface layer, while a full reshaping towards a fcc architecture takes place above 950 K...
January 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#7
Raman Sankar, G Narsinga Rao, I Panneer Muthuselvam, Tay-Rong Chang, H T Jeng, G Senthil Murugan, Wei-Li Lee, F C Chou
The anisotropic superconducting properties of PbTaSe2 single crystal is reported. Superconductivity with T c  =  3.83  ±  0.02 K has been characterized fully with electrical resistivity ρ(T), magnetic susceptibility χ(T), and specific heat C p (T) measurements using single crystal samples. The superconductivity is type-II with lower critical field H c1 and upper critical field H c2 of 65 and 450 Oe (H⊥  to the ab-plane), 140 and 1500 Oe (H|| to the ab-plane), respectively. These results indicate that the superconductivity of PbTaSe2 is anisotropic...
January 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#8
Prescott Evans, P A Dowben
Further analysis of the resonant photoemission data, found within Sundar et al (2016 J. Phys.: Condens. Matter 28 315502), show the intensities do not follow the elemental composition in the Mo1-x Re x alloy. Similar trends are observed in the published data for Gd1-x Ni x alloy films. The analysis of the resonant photoemission intensities suggests that Mo in the Mo1-x Re x alloy and Gd in the Gd1-x Ni x alloy have nearest neighbor bonds to Re and Ni respectively. This means the A-B bond is favored over the average of the A-A bond and the B-B bond in these binary alloys, so that the short range order favors strong local ordering rather than clustering alloys...
January 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#9
P Yatsyshin, A O Parry, C Rascón, S Kalliadasis
Even simple fluids on simple substrates can exhibit very rich surface phase behaviour. To illustrate this, we consider fluid adsorption on a planar wall chemically patterned with a deep stripe of a different material. In this system, two phase transitions compete: unbending and pre-wetting. Using microscopic density-functional theory, we show that, for thin stripes, the lines of these two phase transitions may merge, leading to a new two-dimensional-like wetting transition occurring along the walls. The influence of intermolecular forces and interfacial fluctuations on this phase transition and at complete pre-wetting are considered in detail...
January 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#10
Stefano Bonetti
Understanding how spins move in time and space is the aim of both fundamental and applied research in modern magnetism. Over the past three decades, research in this field has led to technological advances that have had a major impact on our society, while improving the understanding of the fundamentals of spin physics. However, important questions still remain unanswered, because it is experimentally challenging to directly observe spins and their motion with a combined high spatial and temporal resolution...
January 18, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#11
Christian H Schiegg, Michael Dzierzawa, Ulrich Eckern
We consider two modifications of a recently proposed three-terminal quantum dot heat engine. First, we investigate the necessity of the thermalization assumption, namely that electrons are always thermalized by inelastic processes when traveling across the cavity where the heat is supplied. Second, we analyze various arrangements of tunneling-coupled quantum dots in order to implement a transmission function that is superior to the Lorentzian transmission function of a single quantum dot. We show that the maximum power of the heat engine can be improved by about a factor of two, even for a small number of dots, by choosing an optimal structure...
January 17, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#12
M Romanini, J L Tamarit, L C Pardo, F J Bermejo, R Fernandez-Perea, F L Pratt
The transition taking place between two metastable phases in 2-O-adamantane, namely the [Formula: see text] cubic, rotator phase and the lower temperature P21/c, Z  =  4 substitutionally disordered crystal is studied by means of muon spin rotation and relaxation techniques. Measurements carried out under zero, weak transverse and longitudinal fields reveal a temperature dependence of the relaxation parameters strikingly similar to those exhibited by structural glass[Formula: see text]liquid transitions (Bermejo et al 2004 Phys...
January 17, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#13
Aurelien Crut, Paolo Maioli, Fabrice Vallee, Natalia Del Fatti
Single-particle optical investigations have greatly improved our understanding of the fundamental properties of nano-objects, avoiding the spurious inhomogeneous effects that affect ensemble experiments. Correlation with high-resolution imaging techniques providing morphological information (e.g., electron microscopy) allows a quantitative interpretation of the optical measurements by means of analytical models and numerical simulations. In this topical review, we first briefly recall the principles underlying some of the most commonly used single-particle optical techniques: near-field, dark-field, spatial modulation and photothermal microscopies/spectroscopies...
January 17, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#14
Madhumita Dalal, Ayan Mallick, Jean-Marc Greneche, Dipankar Das, Pabitra K Chakrabarti
Nanocrystalline samples of Ni0.3Zn0.4Co0.2Cu0.1Fe2O4 (NZCCF) are prepared by a simple co-precipitation method. To obtain nanoparticles of different sizes, the as prepared sample is annealed at 400, 600, 800 and 1000 °C. Nanoparticles of the sample annealed at 600 °C are encapsulated in multi-walled carbon nanotubes (MWCNT). To confirm the crystallographic phase, x-ray diffraction (XRD) patterns are analyzed by the Rietveld method and cation distribution in A- and B-sites is estimated from the analysis. Occupancy of Zn(2+) ions in A-site and that of Fe(3+) ions in B-site increase with the increase of annealing temperature (T A) and lattice parameters lie within 8...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#15
Marcin M Wysokiński, Jan Kaczmarczyk
We investigate the effect of the electron-hole (e-h) symmetry breaking on d-wave superconductivity induced by non-local effects of correlations in the generalized Hubbard model. The symmetry breaking is introduced in a two-fold manner: by the next-to-nearest neighbor hopping of electrons and by the charge-bond interaction-the off-diagonal term of the Coulomb potential. Both terms lead to a pronounced asymmetry of the superconducting order parameter. The next-to-nearest neighbor hopping enhances superconductivity for h-doping, while diminishes it for e-doping...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#16
Ruggero Cortini, Xiaolin Cheng, Jeremy C Smith
Electrostatic interactions between DNA molecules have been extensively studied experimentally and theoretically, but several aspects (e.g. its role in determining the pitch of the cholesteric DNA phase) still remain unclear. Here, we performed large-scale all-atom molecular dynamics simulations in explicit water and 150 mM sodium chloride, to reconstruct the potential of mean force (PMF) of two DNA oligomers 24 base pairs long as a function of their interaxial angle and intermolecular distance. We find that the potential of mean force is dominated by total DNA charge, and not by the helical geometry of its charged groups...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#17
Bret C Hess, Erik K Swenson
This systematic study of transition metal (TM) substitution for H on graphane TM x H1-x C, (TM  =  Sc, Ti, V, Cr, Mn) combines ab initio calculations and cluster expansion to explore a huge variety of structures in more than 20 supercells over the full concentration range from x  =  0 to 1. We find energetically favorable structures at each concentration in supercells not studied before. At low x the lowest-energy structures contain lines and bands of TM atoms. For the larger atoms (Sc, Ti, V) the ordering becomes complex at higher concentrations, and their increased interaction in graphene causes H atoms to detach from the graphene to positions above the TMs...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#18
Asaf Dahan, Assaf Levanon, Mordechai Katz, Haim Suchowski
We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#19
Amit N Shocron, Matthew E Suss
Capacitive deionization (CDI) is a technology in which water is desalinated by ion electrosorption into the electric double layers (EDLs) of charging porous electrodes. In recent years significant advances have been made in modeling the charge and salt dynamics in a CDI cell, but the possible effect of surface transport within diffuse EDLs on these dynamics has not been investigated. We here present theory which includes surface transport in describing the dynamics of a charging CDI cell. Through our numerical solution to the presented models, the possible effect of surface transport on the CDI process is elucidated...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#20
J R Panter, H Kusumaatmaja
The fundamental impacts of surface geometry on the stability of wetting states, and the transitions between them are elucidated for square posts and reentrant structures in three dimensions. We identify three principal outcomes of particular importance for future surface design of liquid-repellent surfaces. Firstly, we demonstrate and quantify how capillary condensation and vapour cavitation affect wetting state stabilities. At high contact angles, cavitation is enhanced about wide, closely-spaced square posts, leading to the existence of suspended states without an associated collapsed state...
January 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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