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1.0

Jun 29, 2018
06/18

by
. Piretto; S. Musacchio; G. Boffetta

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We study the time irreversibility of the direct cascade in two-dimensional turbulence by looking at the time derivative of the square vorticity along Lagrangian trajectories, a quantity which we call metenstrophy. By means of extensive numerical simulations we measure the time irreversibility from the asymmetry of the PDF of the metenstrophy and we find that it increases with the Reynolds number of the cascade, similarly to what found in three-dimensional turbulence. A detailed analysis of the...

Topics: Nonlinear Sciences, Fluid Dynamics, Statistical Mechanics, Condensed Matter, Physics, Chaotic...

Source: http://arxiv.org/abs/1607.06210

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0.0

Jun 28, 2018
06/18

by
A Bailly-Reyre; H. T. Diep; M Kaufman

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We study in this paper the phase transition in a mobile Potts model by the use of Monte Carlo simulation. The mobile Potts model is related to a diluted Potts model which is also studied here by a mean-field approximation. We consider a lattice where each site is either vacant or occupied by a $q$-state Potts spin. The Potts spin can move from one site to a nearby vacant site. In order to study the surface sublimation, we consider a system of Potts spins contained in a recipient with a...

Topics: Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1510.04460

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0.0

Jun 28, 2018
06/18

by
A Bedini; A L Owczarek; T Prellberg

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We study via Monte Carlo simulation a generalisation of the so-called vertex interacting self-avoiding walk (VISAW) model on the square lattice. The configurations are actually not self-avoiding walks but rather restricted self-avoiding trails (bond avoiding paths) which may visit a site of the lattice twice provided the path does not cross itself: to distinguish this subset of trails we shall call these configurations \emph{grooves}. Three distinct interactions are added to the configurations:...

Topics: Soft Condensed Matter, Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1510.06686

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2.0

Jun 28, 2018
06/18

by
A Bedini; A L Owczarek; T Prellberg

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Various interacting lattice path models of polymer collapse in two dimensions demonstrate different critical behaviours. This difference has been without a clear explanation. The collapse transition has been variously seen to be in the Duplantier-Saleur $\theta$-point university class (specific heat cusp), the interacting trail class (specific heat divergence) or even first-order. Here we study via Monte Carlo simulation a generalisation of the Duplantier-Saleur model on the honeycomb lattice...

Topics: Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1510.06891

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0.0

Jun 28, 2018
06/18

by
A Bérut; A Imparato; A Petrosyan; S Ciliberto

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We experimentally study the statistical properties of the energy fluxes between two trapped Brownian particles, interacting through dissipative hydrodynamic coupling, submitted to an effective temperature difference $\Delta T$, obtained by random forcing the position of one trap. We identify effective heat fluxes between the two particles and show that they satisfy an exchange fluctuation theorem (xFT) in the stationary state. We also show that after the sudden application of a temperature...

Topics: Soft Condensed Matter, Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1510.05083

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1.0

Jun 29, 2018
06/18

by
A C C Coolen

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I report on the development of a novel statistical mechanical formalism for the analysis of random graphs with many short loops, and processes on such graphs. The graphs are defined via maximum entropy ensembles, in which both the degrees (via hard constraints) and the adjacency matrix spectrum (via a soft constraint) are prescribed. The sum over graphs can be done analytically, using a replica formalism with complex replica dimensions. All known results for tree-like graphs are recovered in a...

Topics: Disordered Systems and Neural Networks, Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1601.08124

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1.0

Jun 29, 2018
06/18

by
A García-Fuente; J Carrete; A Vega; L J Gallego

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We report a density-functional-theoretic study of the stability and electronic structure of two recently proposed borophene sheets with Pmmn symmetry and nonzero thickness. We then investigate nanoribbons (BNRs) derived from these nanostructures, with particular attention to technologically relevant properties like magnetism and electronic transport. We consider two perpendicular directions for the edges of the stripes as well as different lateral widths. We show that the Pmmn8 sheet, with 8...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1610.05534

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0.0

Jun 29, 2018
06/18

by
A J Macdonald; Y-S Tremblay-Johnston; S Grothe; S Chi; P Dosanjh; S Johnston; S A Burke

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Fourier transform scanning tunneling spectroscopy (FT-STS), or quasiparticle interference (QPI), has become an influential tool for the study of a wide range of important materials in condensed matter physics. However, FT-STS in complex materials is often challenging to interpret, requiring significant theoretical input in many cases, making it crucial to understand potential artifacts of the measurement. Here, we compare the most common modes of acquiring FT-STS data and show through both...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1606.07402

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3.0

Jun 28, 2018
06/18

by
A Jaouadi; M Telmini; Eric Charron

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In this reply we show that the criticisms raised by J. Noronha are based on a misapplication of the model we have proposed in [A. Jaouadi, M. Telmini, E. Charron, Phys. Rev. A 83, 023616 (2011)]. Here we explicitly discuss the range of validity of the approximations underlying our analytical model. We also show that the discrepancies pointed out for very small atom numbers and for very anisotropic traps are not surprising since these conditions exceed the range of validity of the model.

Topics: Quantum Physics, Quantum Gases, Condensed Matter

Source: http://arxiv.org/abs/1507.02016

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0.0

Jun 30, 2018
06/18

by
A L Grimsmo; A S Parkins; B-S Skagerstam

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We propose a time-delayed feedback control scheme for open quantum systems that can dramatically reduce the time to reach steady state. No measurement is performed in the feedback loop, and we suggest a simple all-optical implementation for a cavity QED system. We demonstrate the potential of the scheme by applying it to a driven and dissipative Dicke model, as recently realized in a quantum gas experiment. The time to reach steady state can then reduced by two orders of magnitude for...

Topics: Quantum Physics, Quantum Gases, Condensed Matter

Source: http://arxiv.org/abs/1401.2287

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0.0

Jun 29, 2018
06/18

by
A Neveu; R Artoni; P Richard; Y Descantes

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Discrete Element Methods (DEM) are a useful tool to model the fracture of cohesive granular materials. For this kind of application, simple particle shapes (discs in 2D, spheres in 3D) are usually employed. However, dealing with more general particle shapes allows to account for the natural heterogeneity of grains inside real materials. We present a discrete model allowing to mimic cohesion between contacting or non-contacting particles whatever their shape in 2D and 3D. The cohesive...

Topics: Soft Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1607.01415

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1.0

Jun 29, 2018
06/18

by
A Pons; T Darnige; Jérôme Crassous; E Clément; Axelle Amon

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Granular packings under constant shear stress display below the Coulomb limit, a logarithmic creep dynamics. However the addition of small stress modulations induces a linear creep regime characterized by an effective viscous response. Using Diffusing Wave Spectroscopy, we investigate the relation between creep and local plastic events spatial distribution ("hot-spots") contributing to the plastic yield. The study is done in the two regimes, i.e. with and without mechanical...

Topics: Soft Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1601.05671

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5.0

Jun 27, 2018
06/18

by
A Ramos-Álvarez; J Mosqueira; F Vidal; Xingye Lu; Huiqian Luo

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We study the diamagnetism induced by thermal fluctuations above the superconducting transition of the iron pnictide Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$ with different doping levels. The measurements are performed with magnetic fields up to 7 T applied in the two main crystal directions. These data provide double information: first, they confirm at a quantitative level the applicability to these materials of a 3D-anisotropic Ginzburg-Landau approach valid in the finite field regime. Then, they allow...

Topics: Superconductivity, Condensed Matter

Source: http://arxiv.org/abs/1506.00170

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0.0

Jun 29, 2018
06/18

by
A Salonen; Cyprien Gay; A Maestro; W Drenckhan; Emmanuelle Rio

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In the present Supplementary notes to our work "Arresting bubble coarsening: A two-bubble experiment to investigate grain growth in presence of surface elasticity" (accepted in EPL), we derive the expression of the gas pressure inside a bubble located above and attached to the circular outlet of a vertical tube.

Topics: Soft Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1612.05754

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0.0

Jun 30, 2018
06/18

by
A Sapora; M Codegone; G Barbero; LR Evangelista

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The adsorption phenomenon of neutral particles from the limiting surfaces of the sample in the Langmuir approximation is investigated. The diffusion equation regulating the redistribution of particles in the bulk is assumed to be of hyperbolic type, in order to take into account the finite velocity of propagation of the density variations. We show that in this framework the condition on the conservation of the number of particles gives rise to a nonlocal boundary condition. We solve the partial...

Topics: Mathematics, Mathematical Physics, Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1402.2853

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7.0

Jun 27, 2018
06/18

by
A Spinelli; M P Rebergen; A F Otte

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Low-dimensional quantum magnetism presents a seemingly unlimited source of rich, intriguing physics. Yet, as realistic experimental representations are hard to come by, the field remains predominantly theoretical. In recent years, artificial spin structures built through manipulation of magnetic atoms in a scanning tunnelling microscope have developed into a promising testing ground for experimental verification of theoretical models. Here we present an overview of available tools and discuss...

Topics: Condensed Matter, Mesoscale and Nanoscale Physics

Source: http://arxiv.org/abs/1504.05021

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4.0

Jun 27, 2018
06/18

by
A Venaille; T Dauxois; S Ruffo

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Understanding the relaxation of a system towards equilibrium is a longstanding problem in statistical mechanics. Here we address the role of long-range interactions in this process by considering a class of two-dimensional or geophysical flows where the interaction between fluid particles varies with the distance as $\sim$ r^($\alpha$--2) with $\alpha$ \textgreater{} 0. Previous studies in the Euler case $\alpha$ = 2 had shown convergence towards a variety of quasi-stationary states by changing...

Topics: Condensed Matter, Fluid Dynamics, Statistical Mechanics, Classical Physics, Physics

Source: http://arxiv.org/abs/1503.07904

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5.0

Jun 28, 2018
06/18

by
A. -A. Homman; J. -B. Maillet; J. Roussel; G. Stoltz

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This work presents new parallelizable numerical schemes for the integration of Dissipative Particle Dynamics with Energy conservation (DPDE). So far, no numerical scheme introduced in the literature is able to correctly preserve the energy over long times and give rise to small errors on average properties for moderately small timesteps, while being straightforwardly parallelizable. We present in this article two new methods, both straightforwardly parallelizable, allowing to correctly preserve...

Topics: Computational Physics, Physics, Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1507.06643

5
5.0

Jun 28, 2018
06/18

by
A. -M. Daré; P. Lombardo

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We analyze an electronic nanoscale thermal machine driven by time-dependent environment: besides bias and gate voltage variations, we consider also the less prevailing time modulation of the couplings between leads and dot. We provide energy and heat current expressions in such situations, as well as expressions for the power exchanged between the dot+leads system and its outside. Calculations are made in the Keldysh nonequilibrium Green's function framework. We apply these results to design a...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1509.05606

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0.0

Jun 30, 2018
06/18

by
A. -M. Daré; P. Lombardo

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We investigate a thermoelectric nano-engine whose properties are steered by Coulomb interaction. The device whose design decouples charge and energy currents is made up of two interacting quantum dots connected to three different reservoirs. We show that, by tailoring the tunnel couplings, this setup can be made very attractive for energy-harvesting prospects, due to a delivered power that can be of the order of the quantum bound [R. S. Whitney, Phys. Rev. Lett. 112, 130601 (2014); Entropy 18,...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1704.04064

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0.0

Jun 29, 2018
06/18

by
A. -M. Tsopelakou; G. Margazoglou; Y. F. Contoyiannis; P. A. Kalozoumis; F. K. Diakonos; N. G. Fytas

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We propose a method for calculating the isothermal critical exponent $\delta$ in Ising systems undergoing a second-order phase transition. It is based on the calculation of the mean magnetization time series within a small connected domain of a lattice after equilibrium is reached. At the pseudocritical point, the magnetization time series attains intermittent characteristics and the probability density for consecutive values of mean magnetization within a region around zero becomes a power...

Topics: Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1601.06306

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0.0

Jun 27, 2018
06/18

by
A. -M. Uimonen; G. Stefanucci; Y. Pavlyukh; R. van Leeuwen

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In a recent paper [Phys. Rev. B 90, 115134 (2014)] we put forward a diagrammatic expansion for the self-energy which guarantees the positivity of the spectral function. In this work we extend the theory to the density response function. We write the generic diagram for the density-response spectrum as the sum of partitions. In a partition the original diagram is evaluated using time-ordered Green's functions (GF) on the left-half of the diagram, antitime-ordered GF on the right-half of the...

Topics: Other Condensed Matter, Condensed Matter, Strongly Correlated Electrons

Source: http://arxiv.org/abs/1503.02158

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0.0

Jun 28, 2018
06/18

by
A. -M. Visuri; T. Giamarchi; P. Törmä

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We study analytically and with the numerical time-evolving block decimation method the dynamics of an impurity in a bath of spinless fermions with nearest-neighbor interactions in a one-dimensional lattice. The bath is in a Mott insulator state with alternating sites occupied and the impurity interacts with the bath by repulsive on-site interactions. We find that when the magnitudes of the on-site and nearest-neighbor interactions are close to each other, the system shows excitations of two...

Topics: Quantum Gases, Strongly Correlated Electrons, Condensed Matter

Source: http://arxiv.org/abs/1511.04276

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0.0

Jun 29, 2018
06/18

by
A. -M. Visuri; J. J. Kinnunen; J. E. Baarsma; P. Törmä

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We study the transport, decoherence and dissipation of an impurity interacting with a bath of free fermions in a one-dimensional lattice. Numerical simulations are made with the time-evolving block decimation method. We introduce a mass imbalance between the impurity and bath particles and find that the fastest decoherence occurs for a light impurity in a bath of heavy particles. By contrast, the fastest dissipation of energy occurs when the masses are equal. We present a simple model for...

Topics: Condensed Matter, Quantum Gases

Source: http://arxiv.org/abs/1604.06638

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0.0

Jun 30, 2018
06/18

by
A. -W. de Leeuw; O. Onishchenko; R. A. Duine; H. T. C. Stoof

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We investigate the superfluid-Mott-insulator transition of a two-dimensional photon gas in a dye-filled optical microcavity and in the presence of a periodic potential. We show that in the random-phase approximation the effects of the dye molecules, which generally lead to dissipation in the photonic system, can be captured by two dimensionless parameters that only depend on dye-specific properties. Within the mean-field approximation, we demonstrate that one of these parameters decreases the...

Topics: Quantum Gases, Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1412.5933

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2.0

Jun 27, 2018
06/18

by
A. -W. de Leeuw; E. C. I. van der Wurff; R. A. Duine; D. van Oosten; H. T. C. Stoof

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We construct a theory for Bose-Einstein condensation of light in nano-fabricated semiconductor microcavities. We model the semiconductor by one conduction and one valence band which consist of electrons and holes that interact via a Coulomb interaction. Moreover, we incorporate screening effects by using a contact interaction with the scattering length for a Yukawa potential and describe in this manner the crossover from exciton gas to electron-hole plasma as we increase the excitation level of...

Topics: Other Condensed Matter, Quantum Gases, Condensed Matter

Source: http://arxiv.org/abs/1505.01732

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0.0

Jun 30, 2018
06/18

by
A. -W. de Leeuw; H. T. C. Stoof; R. A. Duine

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We investigate the finite lifetime effects on first-order correlation functions of dissipative Bose-Einstein condensates. By taking into account the phase fluctuations up to all orders, we show that the finite lifetime effects are neglible for the spatial first-order correlation functions, but have an important effect on the temporal correlations. As an application, we calculate the one-particle density matrix of a quasi-condensate of photons. Finally, we also consider the photons in the normal...

Topics: Quantum Gases, Condensed Matter

Source: http://arxiv.org/abs/1403.8041

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0.0

Jun 29, 2018
06/18

by
A. A. Aczel; A. M. Cook; T. J. Williams; S. Calder; A. D. Christianson; G. -X. Cao; D. Mandrus; Y. B. Kim; A. Paramekanti

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We have performed inelastic neutron scattering (INS) experiments to investigate the magnetic excitations in the weakly distorted face-centered-cubic (fcc) iridate double perovskites La$_2$ZnIrO$_6$ and La$_2$MgIrO$_6$, which are characterized by A-type antiferromagnetic ground states. The powder inelastic neutron scattering data on these geometrically frustrated $j_{\rm eff}=1/2$ Mott insulators provide clear evidence for gapped spin wave excitations with very weak dispersion. The INS results...

Topics: Condensed Matter, Strongly Correlated Electrons

Source: http://arxiv.org/abs/1604.08431

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1.0

Jun 26, 2018
06/18

by
A. A. Aczel; L. Li; V. O. Garlea; J. -Q. Yan; F. Weickert; V. S. Vapf; R. Movshovich; M. Jaime; P. J. Baker; V. Keppens; D. Mandrus

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We have investigated polycrystalline samples of the zigzag chain system BaTb$_2$O$_4$ with a combination of magnetic susceptibility, heat capacity, neutron powder diffraction, and muon spin relaxation measurements. Despite the onset of Tb$^{3+}$ short-range antiferromagnetic correlations at $|\theta_{CW}|$ $=$ 18.5 K and a very large effective moment, our combined measurements indicate that BaTb$_2$O$_4$ remains paramagnetic down to 0.095 K. The magnetic properties of this material show...

Topics: Strongly Correlated Electrons, Condensed Matter

Source: http://arxiv.org/abs/1502.05668

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0.0

Jun 29, 2018
06/18

by
A. A. Aczel; Z. Zhao; S. Calder; D. T. Adroja; P. J. Baker; J. -Q. Yan

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We have performed magnetic susceptibility, heat capacity, neutron powder diffraction, and muon spin relaxation experiments to investigate the magnetic ground states of the 5$d^2$ double perovskites Sr$_2$YReO$_6$ and Sr$_2$InReO$_6$. We find that Sr$_2$YReO$_6$ is a spin glass, while Sr$_2$InReO$_6$ hosts a non-magnetic singlet state. By making detailed comparisons with other 5$d^2$ double perovskites, we argue that a delicate interplay between spin-orbit coupling, non-cubic crystal fields, and...

Topics: Condensed Matter, Strongly Correlated Electrons

Source: http://arxiv.org/abs/1602.02978

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0.0

Jun 30, 2018
06/18

by
A. A. Aczel; L. Li; V. O. Garlea; J. -Q. Yan; F. Weickert; M. Jaime; B. Maiorov; R. Movshovich; L. Civale; V. Keppens; D. Mandrus

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The AR$_2$O$_4$ family (R = rare earth) have recently been attracting interest as a new series of frustrated magnets, with the magnetic R atoms forming zigzag chains running along the $c$-axis. We have investigated polycrystalline BaNd$_2$O$_4$ with a combination of magnetization, heat capacity, and neutron powder diffraction (NPD) measurements. Magnetic Bragg peaks are observed below $T_N$ $=$ 1.7 K, and they can be indexed with a propagation vector of $\vec{k}$ $=$ (0 1/2 1/2). The signal...

Topics: Strongly Correlated Electrons, Condensed Matter

Source: http://arxiv.org/abs/1407.4098

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0.0

Jun 30, 2018
06/18

by
A. A. Aczel; P. J. Baker; D. E. Bugaris; J. Yeon; H. -C. zur Loye; T. Guidi; D. T. Adroja

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We find evidence for long-range and short-range ($\zeta$ $=$ 70 \AA~at 4 K) incommensurate magnetic order on the quasi-face-centered-cubic (FCC) lattices of the monoclinic double perovskites La$_2$NaRuO$_6$ and La$_2$NaOsO$_6$ respectively. Incommensurate magnetic order on the FCC lattice has not been predicted by mean field theory, but may arise via a delicate balance of inequivalent nearest neighbour and next nearest neighbour exchange interactions. In the Ru system with long-range order,...

Topics: Strongly Correlated Electrons, Condensed Matter

Source: http://arxiv.org/abs/1401.1496

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0.0

Jun 27, 2018
06/18

by
A. A. Aligia; P. Roura Bas; S. Florens

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We investigate theorerically the non-equilibrium transport through a molecular quantum dot as a function of gate and bias voltage, taking into account the typical situation in molecular electronics. In this respect, our study includes asymmetries both in the capacitances and tunneling rates to the source and drain electrodes, as well as an infinitely large charging energy on the molecule. Our calculations are based on the out-of-equilibrium Non-Crossing-Approximation (NCA), which is a reliable...

Topics: Mesoscale and Nanoscale Physics, Strongly Correlated Electrons, Condensed Matter

Source: http://arxiv.org/abs/1505.03722

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0.0

Jun 30, 2018
06/18

by
A. A. Aligia

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Using non-equilibrium renormalized perturbation theory to second order in the renormalized Coulomb repulsion, we calculate the lesser $\Sigma^ $ self-energies of the impurity Anderson model, which describes the current through a quantum dot, in the general asymmetric case. While in general a numerical integration is required to evaluate the perturbative result, we derive an analytical approximation for small frequency $\omega$, bias voltage $V$ and temperature $T$ which is exact to total second...

Topics: Mesoscale and Nanoscale Physics, Strongly Correlated Electrons, Condensed Matter

Source: http://arxiv.org/abs/1403.3452

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0.0

Jun 28, 2018
06/18

by
A. A. Boris; V. M. Krasnov

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We study photon assisted tunneling in Nb/AlOx/Nb Josephson junctions. A quantitative calibration of the microwave field in the junction allowed direct verification of the quantum efficiency of microwave photon detection by the junctions. We observe that voltages of photon assisted tunneling steps vary both with the microwave power and the tunneling current. However, this variation is not monotonous, but staircase-like. The phenomenon is caused by mutual locking of positive and negative step...

Topics: Superconductivity, Condensed Matter

Source: http://arxiv.org/abs/1510.06775

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1.0

Jun 28, 2018
06/18

by
A. A. Burkov

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Perspectives article on J. Xiong et al., Science 350, 413 (2015).

Topics: Condensed Matter, Popular Physics, Mesoscale and Nanoscale Physics, Physics

Source: http://arxiv.org/abs/1511.03621

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0.0

Jun 30, 2018
06/18

by
A. A. Burkov

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Weyl metal is the first example of a conducting material with a nontrivial electronic structure topology, making it distinct from an ordinary metal. Unlike in insulators, the nontrivial topology is not related to invariants, associated with completely filled bands, but with ones, associated with the Fermi surface. The Fermi surface of a topological metal consists of disconnected sheets, each enclosing a Weyl node, which is a point of contact between two nondegenerate bands. Such a point contact...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1704.06660

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0.0

Jun 30, 2018
06/18

by
A. A. Burkov

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We present a theory of the anomalous Hall effect (AHE) in a doped Weyl semimetal, or Weyl metal, including both intrinsic and extrinsic (impurity scattering) contributions. We demonstrate that a Weyl metal is distinguished from an ordinary ferromagnetic metal by the absence of the extrinsic and the Fermi surface part of the intrinsic contributions to the AHE, as long as the Fermi energy is sufficiently close to the Weyl nodes. The AHE in a Weyl metal is thus shown to be a purely intrinsic,...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1406.3033

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6.0

Jun 26, 2018
06/18

by
A. A. Burkov

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We present an overview of our recent work on transport phenomena in Weyl metals, which may be connected to their nontrivial topological properties, particularly to chiral anomaly. We argue that there are two basic phenomena, which are related to chiral anomaly in Weyl metals: Anomalous Hall Effect (AHE) and Chiral Magnetic Effect (CME). While AHE is in principle present in any ferromagnetic metal, we demonstrate that a magnetic Weyl metal is distinguished from an ordinary ferromagnetic metal by...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1502.07609

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0.0

Jun 30, 2018
06/18

by
A. A. Burkov

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We present a microscopic theory of diffusive magnetotransport in Weyl metals and clarify its relation to chiral anomaly. We derive coupled diffusion equations for the total and axial charge densities and show that chiral anomaly manifests as a magnetic-field-induced coupling between them. We demonstrate that a universal experimentally-observable consequence of this coupling in magnetotransport in Weyl metals is a quadratic negative magnetoresistance, which will dominate all other contributions...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1409.0013

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Jun 29, 2018
06/18

by
A. A. Burkov

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Topological semimetals and metals have emerged as a new frontier in the field of quantum materials. Novel macroscopic quantum phenomena they exhibit are not only of fundamental interest, but may hold some potential for technological applications.

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1610.07866

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Jun 30, 2018
06/18

by
A. A. Burkov

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We present a theory of the intrinsic anomalous Hall effect in a model of a doped Weyl semimetal, which serves here as the simplest toy model of a generic three-dimensional metallic ferromagnet with Weyl nodes in the electronic structure. We analytically evaluate the anomalous Hall conductivity as a function of doping, which allows us to explicitly separate the Fermi surface and non Fermi surface contributions to the Hall conductivity by carefully evaluating the zero frequency and zero...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1401.0066

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Jun 27, 2018
06/18

by
A. A. Burkov

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It has recently been found that Dirac and Weyl metals are characterized by an unusual weak-field longitudinal magnetoresistance: large, negative, and quadratic in the magnetic field. This has been shown to arise from chiral anomaly, i.e. nonconservation of the chiral charge in the presence of external electric and magnetic fields, oriented collinearly. In this paper we report on a theory of this effect in both Dirac and Weyl metals. We demonstrate that this phenomenon contains two important...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1505.01849

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Jun 30, 2018
06/18

by
A. A. Burlakov; V. L. Gurtovoi; A. I. Ilin; A. V. Nikulov; V. A. Tulin

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A new type of a superconducting quantum interference device (SQUID) based on a single superconducting loop without Josephson junctions and with asymmetric link-up of current leads is proposed. This SQUID offers advantages in simplicity of fabrication and higher sensitivity of magnetic flux. Magnetic field dependence of the critical current in aluminium rings with asymmetric link-up of current leads has been measured in order to confirm the possibility of making this type of SQUID.

Topics: Superconductivity, Condensed Matter

Source: http://arxiv.org/abs/1403.7113

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4.0

Jun 26, 2018
06/18

by
A. A. Caparica; Salviano A. Leão; Claudio J. DaSilva

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Here we report a precise computer simulation study of the static critical properties of the two-dimensional $q$-states Potts model using very accurate data obtained from a modified Wang-Landau (WL) scheme proposed by Caparica and Cunha-Netto [Phys. Rev. E {\bf 85}, 046702 (2012)]. This algorithm is an extension of the conventional WL sampling, but the authors changed the criterion to update the density of states during the random walk and established a new procedure to windup the simulation...

Topics: Condensed Matter, Statistical Mechanics

Source: http://arxiv.org/abs/1501.03708

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Jun 30, 2018
06/18

by
A. A. Castro; O. Olicón; R. Escamilla; F. Morales

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We studied the effects of substitution of Pd by Cu on the upper critical field of the noncentrosymmetric superconductor Li$_2$Pd$_{3-x}$Cu$_x$B, with x=0.0, 0.1 and 0.2. The upper critical field as a function of temperature was determined by resistance measurements at different magnetic fields. We found that the superconducting transition temperature decreases as the Cu content increases. Moreover, the temperature dependence of the upper critical field is linear in the range of the temperature...

Topics: Condensed Matter, Superconductivity

Source: http://arxiv.org/abs/1703.02669

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Jun 29, 2018
06/18

by
A. A. Chernyuk; V. I. Sugakov; V. V. Tomylko

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The appearance of the non-homogeneous structures of the indirect exciton density distribution in the region of the quantum well (in the region of the inner ring) is explained. The structure (the fragmentation) occurs due to the exciton condensed phase formation because of interaction between excitons. The formation of the structure is related with the non-equalibrity of the system, which is caused by the exciton finite lifetime and the presence of the pumpimg. The structure emerges in the shape...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1609.00202

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Jun 30, 2018
06/18

by
A. A. Eremko; L. S. Brizhik; V. M. Loktev

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The problem of the spin states corresponding to the solutions of Dirac equation is studied. In particular, the three sets of the eigenfunctions of Dirac equation are obtained. In each set the wavefunction is at the same time the eigenfunction of one of the three spin operators, which do not commute with each other, but do commute with the Dirac Hamiltonian. This means that the eigenfunctions of Dirac equation describe three independent spin states. The energy spectrum is calculated for each of...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1408.6078

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Jun 28, 2018
06/18

by
A. A. Eremko; L. S. Brizhik; V. M. Loktev

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The general solution of the Dirac equation for quasi-two-dimensional electrons confined in an asymmetric quantum well, is found. The energy spectrum of such a system is exactly calculated using special unitary transformation and shown to depend on the electron spin polarization. The general solution, being the only one, contains free parameters, whose variation continuously transforms one known particular solution into another. As an example, two different cases are considered in detailL:...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1511.04034

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Jun 30, 2018
06/18

by
A. A. Fernández-Marín; J. A. Méndez-Bermúdez; J. Carbonell; F. Cervera; J. Sánchez-Dehesa; V. A. Gopar

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Experimental evidence demonstrating that anomalous localization of waves can be induced in a controllable manner is reported. A microwave waveguide with dielectric slabs randomly placed is used to confirm the presence of anomalous localization. If the random spacing between slabs follows a distribution with a power-law tail (L\'evy-type distribution), unconventional properties in the microwave-transmission fluctuations take place revealing the presence of anomalous localization. We study both...

Topics: Physics, Optics, Disordered Systems and Neural Networks, Condensed Matter

Source: http://arxiv.org/abs/1411.1271