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2016-11-29
Dissipative self-gravitating Bose-Einstein condensates with arbitrary nonlinearity as a model of dark matter halos
We develop a general formalism applying to Newtonian self-gravitating Bose-Einstein condensates. This formalism may find application in the context of dark matter halos. We introduce a generalized Gross-Pitaevskii equation including a source of dissipation (damping) and an arbitrary nonlinearity. Using the Madelung tra...
1611.09610v1
2016-12-06
Breakdown of Fermi liquid theory in topological multi-Weyl semimetals
Fermi liquid theory works very well in most normal metals, but is found violated in many strongly correlated electron systems, such as cuprate and heavy-fermion superconductors. A widely accepted criterion is that, the Fermi liquid theory is valid when the interaction-induced fermion damping rate approaches zero more r...
1612.01729v2
2016-12-08
Quantifying acoustic damping using flame chemiluminescence
Thermoacoustic instabilities in gas turbines and aeroengine combustors falls within the category of complex systems. They can be described phenomenologically using nonlinear stochastic differential equations, which constitute the grounds for output-only model-based system identification. It has been shown recently that...
1612.02609v1
2016-12-29
A quasi-mode theory of chiral phonons
The coherence properties of mechanical resonators are often limited by multiple unavoidable forms of loss -- including phonon-phonon and phonon-defect scattering -- which result in the scattering of sound into other resonant modes and into the phonon bath. Dynamic suppression of this scattering loss can lift constraint...
1612.09240v1
2017-01-03
A Model for Dissipation of Solar Wind Magnetic Turbulence by Kinetic Alfvén Waves at Electron Scales: Comparison with Observations
In hydrodynamic turbulence, it is well established that the length of the dissipation scale depends on the energy cascade rate, i.e., the larger the energy input rate per unit mass, the more the turbulent fluctuations need to be driven to increasingly smaller scales to dissipate the larger energy flux. Observations of ...
1701.00680v1
2017-02-07
Constraining color flavor locked strange stars in the gravitational wave era
We perform a detailed analysis of the fundamental mode of non-radial pulsations of color flavor locked strange stars. Solving the general relativistic equations for non-radial pulsations for an equation of state derived within the MIT bag model, we calculate the frequency and the gravitational damping time of the funda...
1702.02081v1
2017-02-16
Designing the Optimal Bit: Balancing Energetic Cost, Speed and Reliability
We consider the technologically relevant costs of operating a reliable bit that can be erased rapidly. We find that both erasing and reliability times are non-monotonic in the underlying friction, leading to a trade-off between erasing speed and bit reliability. Fast erasure is possible at the expense of low reliabilit...
1702.04950v2
2017-03-07
Higgs Modes in the Pair Density Wave Superconducting State
The pair density wave (PDW) superconducting state has been proposed to explain the layer- decoupling effect observed in the compound La$_{2-x}$Ba$_x$CuO$_4$ at $x=1/8$ (Phys. Rev. Lett. 99, 127003). In this state the superconducting order parameter is spatially modulated, in contrast with the usual superconducting (SC)...
1703.02541v2
2017-04-29
Low-frequency wide band-gap elastic/acoustic meta-materials using the K-damping concept
The terms "acoustic/elastic meta-materials" describe a class of periodic structures with unit cells exhibiting local resonance. This localized resonant structure has been shown to result in negative effective stiffness and/or mass at frequency ranges close to these local resonances. As a result, these structures presen...
1705.00226v2
2017-05-07
Precision cosmology with redshift-space bispectrum: a perturbation theory based model at one-loop order
The large-scale matter distribution in the late-time Universe exhibits gravity-induced non-Gaussianity, and the bispectrum, three-point cumulant is expected to contain significant cosmological information. In particular, the measurement of the bispectrum helps to tighten the constraints on dark energy and modified grav...
1705.02574v1
2017-05-13
Large-amplitude longitudinal oscillations in a solar filament
In this paper, we report our multiwavelength observations of the large-amplitude longitudinal oscillations of a filament on 2015 May 3. Located next to active region 12335, the sigmoidal filament was observed by the ground-based H$\alpha$ telescopes from GONG and by AIA aboard SDO. The filament oscillations were most p...
1705.04820v1
2017-05-14
Inter-Area Oscillation Damping With Non-Synchronized Wide-Area Power System Stabilizer
One of the major issues in an interconnected power system is the low damping of inter-area oscillations which significantly reduces the power transfer capability. Advances in Wide-Area Measurement System (WAMS) makes it possible to use the information from geographical distant location to improve power system dynamics ...
1705.04953v2
2017-05-19
Analytical Prediction of Reflection Coefficients for Wave Absorbing Layers in Flow Simulations of Regular Free-Surface Waves
Undesired wave reflections, which occur at domain boundaries in flow simulations with free-surface waves, can be minimized by applying source terms in the vicinity of the boundary to damp the waves. Examples of such approaches are absorbing layers, damping zones, forcing zones, relaxation zones and sponge layers. A pro...
1705.06940v2
2017-06-16
Challenges testing the no-hair theorem with gravitational waves
General relativity's no-hair theorem states that isolated astrophysical black holes are described by only two numbers: mass and spin. As a consequence, there are strict relationships between the frequency and damping time of the different modes of a perturbed Kerr black hole. Testing the no-hair theorem has been a long...
1706.05152v2
2017-06-26
Simulating the effect of high column density absorbers on the one-dimensional Lyman-alpha forest flux power spectrum
We measure the effect of high column density absorbing systems of neutral hydrogen (HI) on the one-dimensional (1D) Lyman-alpha forest flux power spectrum using cosmological hydrodynamical simulations from the Illustris project. High column density absorbers (which we define to be those with HI column densities $N(\mat...
1706.08532v2
2017-07-19
Engineering elliptical spin-excitations by complex anisotropy fields in Fe adatoms and dimers on Cu(111)
We investigate the dynamics of Fe adatoms and dimers deposited on the Cu(111) metallic surface in the presence of spin-orbit coupling, within time-dependent density functional theory. The \textit{ab initio} results provide material-dependent parameters that can be used in semiclassical approaches, which are used for in...
1707.06087v2
2017-10-02
The gas and stellar mass of low-redshift damped Lyman-$α$ absorbers
We report Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet and Arecibo Telescope H{\sc i} 21cm spectroscopic studies of six damped and sub-damped Lyman-$\alpha$ absorbers (DLAs and sub-DLAs, respectively) at $z \lesssim 0.1$, that have yielded estimates of their H{\sc i} column density, metallicity an...
1710.00710v1
2017-10-25
Two-Level System Damping in a Quasi-One-Dimensional Optomechanical Resonator
Nanomechanical resonators have demonstrated great potential for use as versatile tools in a number of emerging quantum technologies. For such applications, the performance of these systems is restricted by the decoherence of their fragile quantum states, necessitating a thorough understanding of their dissipative coupl...
1710.09439v3
2017-11-10
Vortex axisymmetrization, inviscid damping, and vorticity depletion in the linearized 2D Euler equations
Coherent vortices are often observed to persist for long times in turbulent 2D flows even at very high Reynolds numbers and are observed in experiments and computer simulations to potentially be asymptotically stable in a weak sense for the 2D Euler equations. We consider the incompressible 2D Euler equations linearize...
1711.03668v1
2017-11-15
Anomalous spin-orbit torque switching due to field-like torque-assisted domain wall reflection
Spin-orbit torques (SOT) allow the electrical control of magnetic states. Current-induced SOT switching of the perpendicular magnetization is of particular technological importance. The SOT consists of damping-like and field-like torques so that the efficient SOT switching requires to understand combined effects of the...
1711.05367v1
2017-11-24
Influence of surfactants on the electrohydrodynamic stretching of water drops in oil
In this paper we present experimental and numerical studies of the electrohydrodynamic stretching of a sub-millimetre-sized salt water drop, immersed in oil with added non-ionic surfactant, and subjected to a suddenly applied electric field of magnitude approaching 1 kV/mm. By varying the drop size, electric field stre...
1711.08969v2
2017-11-30
Model-independent analysis of the DAMPE excess
The Dark Matter Particle Explorer (DAMPE) recently released measurements of the electron spectrum with a hint of a narrow peak at about 1.4 TeV. We investigate dark matter (DM) models that could produce such a signal by annihilation in a nearby subhalo whilst simultaneously satisfying constraints from DM searches. In o...
1711.11376v3
2017-12-07
Flavor Structure of the Cosmic-Ray Electron/Positron Excesses at DAMPE
The Dark Matter Particle Explorer (DAMPE) satellite detector announced its first result for measuring the cosmic-ray electron/positron (CRE) energy spectrum up to 4.6TeV, including a tentative peak-like event excess at (1.3-1.5)TeV. In this work, we uncover a significant hidden excess in the DAMPE CRE spectrum over the...
1712.02744v3
2017-12-20
Unifying ultrafast demagnetization and intrinsic Gilbert damping in Co/Ni bilayers with electronic relaxation near the Fermi surface
The ability to controllably manipulate the laser-induced ultrafast magnetic dynamics is a prerequisite for future high speed spintronic devices. The optimization of devices requires the controllability of the ultrafast demagnetization time, , and intrinsic Gilbert damping, . In previous attempts to establish the relati...
1712.07323v1
2017-12-22
Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: A two-fluid hydrodynamic description
We provide a description of the dynamic structure factor of a homogeneous unitary Fermi gas at low momentum and low frequency, based on the dissipative two-fluid hydrodynamic theory. The viscous relaxation time is estimated and is used to determine the regime where the hydrodynamic theory is applicable and to understan...
1712.08320v1
2018-01-15
Amplitude- and gas pressure-dependent nonlinear damping of high-Q oscillatory MEMS micro mirrors
Silicon-based micro-electromechanical systems (MEMS) can be fabricated using bulk and surface micromachining technology. A micro mirror designed as an oscillatory MEMS constitutes a prominent example. Typically, in order to minimize energy consumption, the micro mirror is designed to have high quality factors. In addit...
1801.04758v2
2018-01-30
Model Based Active Slosh Damping Experiment
This paper presents a model based experimental investigation to demonstrate the usefulness of an active damping strategy to manage fluid sloshing motion in spacecraft tanks. The active damping strategy is designed to reduce the degrading impact on maneuvering and pointing performance via a force feedback strategy. Many...
1801.10017v1
2018-03-22
Propagative and diffusive regimes of acoustic damping in bulk amorphous material
In amorphous solids, a non-negligible part of thermal conductivity results from phonon scattering on the structural disorder. The conversion of acoustic energy into thermal energy is often measured by the Dynamical Structure Factor (DSF) thanks to inelastic neutron or X-Ray scattering. The DSF is used to quantify the d...
1803.08594v1
2018-04-11
Axial quasi-normal modes of neutron stars in $R^2$ gravity
In the present paper the axial quasi-normal modes of neutron stars in $f(R)$ gravity are examined using a large set of equations of state. The numerical calculations are made using two different approaches -- performing time evolution of the perturbation equations and solving the time-independent representation of the ...
1804.04060v1
2018-05-10
Dust modification of the plasma conductivity in the mesosphere
Relative transverse drift (with respect to the ambient magnetic field) between the weakly magnetized electrons and the unmagnetized ions at the lower altitude (80 km) and between the weakly magnetized ions and unmagnetized dust at the higher altitude (90 km) gives rise to the finite Hall conductivity in the Earth's mes...
1805.03799v1
2018-05-19
Migration of Planets Into and Out of Mean Motion Resonances in Protoplanetary Discs: Overstability of Capture and Nonlinear Eccentricity Damping
A number of multiplanet systems are observed to contain planets very close to mean motion resonances, although there is no significant pileup of precise resonance pairs. We present theoretical and numerical studies on the outcome of capture into first-order mean motion resonances (MMRs) using a parametrized planet migr...
1805.07501v1
2018-06-04
Density Waves and the Viscous Overstability in Saturn's Rings
This paper addresses resonantly forced spiral density waves in a dense planetary ring which is close to the threshold for viscous overstability. We solve numerically the hydrodynamical equations for a dense, axisymmetric thin disk in the vicinity of an inner Lindblad resonance with a perturbing satellite. The spiral sh...
1806.01211v3
2018-07-02
Thermoplasmonic behavior of semiconductor nanoparticles: A comparison with metals
A number of applications in nanoplasmonics utilize noble metals, gold (Au) and silver (Ag), as the materials of choice. However, these materials suffer from problems of poor thermal and chemical stability accompanied by significant dissipative losses under high-temperature conditions. In this regard, semiconductor nano...
1807.00881v1
2018-07-26
Aspherical deformations of the Choptuik spacetime
We perform dynamical and nonlinear numerical simulations to study critical phenomena in the gravitational collapse of massless scalar fields in the absence of spherical symmetry. We evolve axisymmetric sets of initial data and examine the effects of deviation from spherical symmetry. For small deviations we find values...
1807.10342v2
2018-08-03
Witnessing galaxy assembly at the edge of the reionization epoch
We report the discovery of Serenity-18, a galaxy at z=5.939 for which we could measure the content of molecular gas, M(H_2)~ 5 x10^9 M_sun, traced by the CO(6-5) emission, together with the metal-poor ([Fe/H]=-3.08 +- 0.12, [Si/H]=-2.86 +- 0.14) gas clump/filament which is possibly feeding its growth. The galaxy has an...
1808.01146v2
2018-08-13
Fluidization of collisionless plasma turbulence
In a collisionless, magnetized plasma, particles may stream freely along magnetic-field lines, leading to phase "mixing" of their distribution function and consequently to smoothing out of any "compressive" fluctuations (of density, pressure, etc.,). This rapid mixing underlies Landau damping of these fluctuations in a...
1808.04284v1
2018-08-15
Neural Material: Learning Elastic Constitutive Material and Damping Models from Sparse Data
The accuracy and fidelity of deformation simulations are highly dependent upon the underlying constitutive material model. Commonly used linear or nonlinear constitutive material models only cover a tiny part of possible material behavior. In this work we propose a unified framework for modeling deformable material. Th...
1808.04931v1
2018-09-06
Forming Gliese 876 Through Smooth Disk Migration
We run a suite of dissipative N-body simulations to determine which regions of phase space for smooth disk migration are consistent with the GJ876 system, an M-dwarf hosting three planets orbiting in a chaotic 4:2:1 Laplace resonance. We adopt adaptive mesh refinement (AMR) methods which are commonly used in hydrodynam...
1809.02200v2
2018-09-15
New closures for more precise modeling of Landau damping in the fluid framework
Incorporation of kinetic effects such as Landau damping into a fluid framework was pioneered by Hammett and Perkins PRL 1990, by obtaining closures of the fluid hierarchy, where the gyrotropic heat flux fluctuations or the deviation of the 4th-order gyrotropic fluid moment, are expressed through lower-order fluid momen...
1809.05718v1
2018-10-04
Sub-photospheric turbulence as a heating mechanism in gamma-ray bursts
We examine the possible role of turbulence in feeding the emission of gamma-ray bursts (GRBs). Turbulence may develop in a GRB jet as the result of hydrodynamic or current-driven instabilities. The jet carries dense radiation and the turbulence cascade can be damped by Compton drag, passing kinetic fluid energy to phot...
1810.02228v1
2018-10-15
Zombie Vortex Instability. III. Persistence with Nonuniform Stratification and Radiative Damping
The Zombie Vortex Instability (ZVI) occurs in the dead zones of protoplanetary disks (PPDs) where perturbations excite baroclinic critical layers, generating "zombie" vortices and turbulence. In this work, we investigate ZVI with nonuniform vertical stratification; while ZVI is triggered in the stratified regions away ...
1810.06588v1
2018-09-21
High performance passive vibration isolation system for optical tables using six-degree-of-freedom viscous damping combined with steel springs
Mechanical vibrations in buildings are ubiquitous. Such vibrations limit the performance of sensitive instruments used, for example, for high-precision manufacturing, nanofabrication, metrology, medical systems, or microscopy. For improved precision, instruments and optical tables need to be isolated from mechanical vi...
1810.06641v4
2018-10-17
Resonance-broadened transit time damping of particles in MHD turbulence
As a fundamental astrophysical process, the scattering of particles by turbulent magnetic fields has its physical foundation laid by the magnetohydrodynamic (MHD) turbulence theory. In the framework of the modern theory of MHD turbulence, we derive a generalized broadened resonance function by taking into account both ...
1810.07726v1
2018-10-23
Calibration of the DAMPE Plastic Scintillator Detector and its on-orbit performance
DArk Matter Particle Explorer (DAMPE) is a space-borne apparatus for detecting the high-energy cosmic-rays like electrons, $\gamma$-rays, protons and heavy-ions. Plastic Scintillator Detector (PSD) is the top-most sub-detector of the DAMPE. The PSD is designed to measure the charge of incident high-energy particles and...
1810.09901v1
2018-10-25
Charge Measurement of Cosmic Ray Nuclei with the Plastic Scintillator Detector of DAMPE
One of the main purposes of the DArk Matter Particle Explorer (DAMPE) is to measure the cosmic ray nuclei up to several tens of TeV or beyond, whose origin and propagation remains a hot topic in astrophysics. The Plastic Scintillator Detector (PSD) on top of DAMPE is designed to measure the charges of cosmic ray nuclei...
1810.10784v1
2018-11-14
Anderson-Bogoliubov and Carlson-Goldman modes in counterflow superconductors: Case study of a double monolayer graphene
The impact of electron-hole pairing on the spectrum of plasma excitations in double layer systems is investigated. The theory is developed with reference to a double monolayer graphene. Taking into account the coupling of scalar potential oscillations with oscillations of the order parameter $\Delta$, we show that the ...
1811.05899v3
2018-12-07
Magnetic Braking and Damping of Differential Rotation in Massive Stars
Fragmentation of highly differentially rotating massive stars that undergo collapse has been suggested as a possible channel for binary black hole formation. Such a scenario could explain the formation of the new population of massive black holes detected by the LIGO/VIRGO gravitational wave laser interferometers. We p...
1812.03176v3
2018-12-18
Inferring physical parameters in solar prominence threads
High resolution observations have permitted to resolve the solar prominences/filaments as sets of threads/fibrils. However, the values of the physical parameters of these threads and their structuring remain poorly constrained. We use prominence seismology techniques to analyse transverse oscillations in threads throug...
1812.07262v1
2019-01-07
Abnormal anti-crossing effect in photon-magnon coupling
We report the experimental demonstration of an abnormal, opposite anti-crossing effect in a photon-magnon-coupled system that consists of an Yttrium Iron Garnet film and an inverted pattern of split-ring resonator structure (noted as ISRR) in a planar geometry. It is found that the normal shape of anti-crossing dispers...
1901.01729v2
2019-01-24
A compact actively damped vibration isolation platform for optical experiments in ultra-high vacuum
We present a tabletop six-axis vibration isolation system, compatible with Ultra-High Vacuum (UHV), which is actively damped and provides 25 dB of isolation at 10 Hz and 65 dB at 100 Hz. While this isolation platform has been primarily designed to support optics in the Laser Interferometer Gravitational-Wave Observator...
1901.09666v2
2019-01-28
Strong damping-like spin-orbit torque and tunable Dzyaloshinskii-Moriya interaction generated by low-resistivity Pd$_{1-x}$Pt$_x$ alloys
Despite their great promise for providing a pathway for very efficient and fast manipulation of magnetization at the nanoscale, spin-orbit torque (SOT) operations are currently energy inefficient due to a low damping-like SOT efficiency per unit current bias, and/or the very high resistivity of the spin Hall materials....
1901.09954v1
2019-02-13
Two-mediator dark matter models and cosmic electron excess
The cosmic electron energy spectrum recently observed by the DAMPE experiment exhibits two interesting features, including a break around 0.9 TeV and a sharp resonance near 1.4 TeV. In this analysis, we propose a dark matter explanation to both exotic features seen by DAMPE. In our model, dark matter annihilates in the...
1902.04916v1
2019-02-18
Coherent control of magnon radiative damping with local photon states
The collective excitation of ordered spins, known as spin waves or magnons, can in principle radiate by emitting travelling photons to an open system when decaying to the ground state. However, in contrast to the electric dipoles, magnetic dipoles contributed by magnons are more isolated from electromagnetic environmen...
1902.06795v2
2019-03-04
Quantum speed limit time for the damped Jaynes-Cummings and Ohmic-like dephasing models in Schwarzschild spacetime
Quantum theory sets the bound on the minimal evolution time between initial and final states of the quantum system. This minimal evolution time can be used to specify the maximal speed of the evolution in open and closed quantum systems. Quantum speed limit is one of the interesting issue in the theory of open quantum ...
1903.01230v2
2019-03-07
Non-linear diffusion of cosmic rays escaping from supernova remnants - II. Hot ionized media
We study the problem of the escape and transport of Cosmic-Rays (CR) from a source embedded in a fully ionised, hot phase of the interstellar medium (HIM). In particular, we model the CR escape and their propagation in the source vicinity taking into account excitation of Alfv\'enic turbulence by CR streaming and mecha...
1903.03193v1
2019-03-25
Stabilised Asynchronous Fast Adaptive Composite Multigrid using Additive Damping
Multigrid solvers face multiple challenges on parallel computers. Two fundamental ones read as follows: Multiplicative solvers issue coarse grid solves which exhibit low concurrency and many multigrid implementations suffer from an expensive coarse grid identification phase plus adaptive mesh refinement overhead. We pr...
1903.10367v3
2019-04-04
The DAMPE excess and gamma-ray constraints
The direct measurements of the cosmic electron-positron spectrum around 1 TeV made by DAMPE have induced many theoretical speculations about possible excesses in the data above the standard astrophysical predictions that might have the dark matter (DM) origin. These attempts mainly fall into two categories: i) DM annih...
1904.02456v2
2019-04-10
Stochastic nonlinear wave dynamics on compact surfaces
We study the Cauchy problem for the nonlinear wave equations (NLW) with random data and/or stochastic forcing on a two-dimensional compact Riemannian manifold without boundary. (i) We first study the defocusing stochastic damped NLW driven by additive space-time white-noise, and with initial data distributed according ...
1904.05277v3
2019-04-30
Damping rates and frequency corrections of Kepler LEGACY stars
Linear damping rates and modal frequency corrections of radial oscillation modes in selected LEGACY main-sequence stars are estimated by means of a nonadiabatic stability analysis. The selected stellar sample covers stars observed by Kepler with a large range of surface temperatures and surface gravities. A nonlocal, t...
1904.13170v1
2019-05-09
An excess of excesses examined via dark matter radio emissions from galaxies
Cosmic-ray and gamma-ray observations have yielded several notable excesses that often lend themselves to explanation by various dark matter annihilation/decay models. In particular, the AMS-02 anti-proton and positron excesses have continued to grow more robust with the collection of more data. This is supplemented by...
1905.05599v5
2019-05-17
Statics and Dynamics of Polymeric Droplets on Chemically Homogeneous and Heterogeneous Substrates
We present a molecular dynamics study of the motion of cylindrical polymer droplets on striped surfaces. We first consider the equilibrium properties of droplets on different surfaces, we show that for small stripes the Cassie-Baxter equation gives a good approximation of the equilibrium contact angle. As the stripe wi...
1905.07214v1
2019-05-20
Exploring the damping of Alfvén waves along a long off-limb coronal loop, up to 1.4 R$_\odot$
The Alfv\'en wave energy flux in the corona can be explored using the electron density and velocity amplitude of the waves. The velocity amplitude of Alfv\'en waves can be obtained from the non-thermal velocity of the spectral line profiles. Previous calculations of the Alfv\'en wave energy flux with height in active r...
1905.08194v2
2019-06-14
Influence of External Magnetic Field on Dust$-$Acoustic Waves in a Capacitive RF Discharge
This paper reports experiments on self$-$excited dust acoustic waves (DAWs) and its propagation characteristics in a magnetized rf discharge plasma. The DAWs are spontaneously excited in dusty plasma after adding more particles in the confining potential well and found to propagate in the direction of streaming ions. T...
1906.06255v2
2019-06-18
A Dynamic Robotic Actuator with Variable Physical Stiffness and Damping
This study is part of research aiming at increasing the range of dynamic tasks for teleoperated field robotics in order to allow operators to use the full range of human motions without being limited by the dynamics of the robotic manipulator. A new variable impedance actuator (VIA) was designed, capable of reproducing...
1906.07669v2
2019-06-27
Frequency Fluctuations in Tunable and Nonlinear Microwave Cavities
We present a model for how frequency fluctuations comparable to the total cavity linewidth may arise in tunable and nonlinear microwave cavities, and how these fluctuations affect the measurement of scattering matrix elements. Applying this model to the specific case of a two-sided cavity, we obtain closed-form express...
1906.11989v3
2019-08-08
Anisotropic damping of the spin fluctuations in doped La2-xSrxCuO4 studied by resonant inelastic x-ray scattering
We report high-resolution resonant inelastic x-ray scattering (RIXS) measurements of the collective spin fluctuations in three compositions of the superconducting cuprate system La2-xSrxCuO4. We have mapped out the excitations throughout much of the 2-D (h,k) Brillouin zone. The spin fluctuations in La2-xSrxCuO4 are fo...
1908.03086v2
2019-08-14
Two-fluid simulations of waves in the solar chromosphere II. Propagation and damping of fast magneto-acoustic waves and shocks
Waves and shocks traveling through the solar chromospheric plasma are influenced by its partial ionization and weak collisional coupling, and may become susceptible to multi-fluid effects, similar to interstellar shock waves. In this study, we consider fast magneto-acoustic shock wave formation and propagation in a str...
1908.05262v1
2019-09-16
Inviscid damping and enhanced dissipation of the boundary layer for 2D Navier-Stokes linearized around Couette flow in a channel
We study the 2D Navier-Stokes equations linearized around the Couette flow $(y,0)^t$ in the periodic channel $\mathbb T \times [-1,1]$ with no-slip boundary conditions in the vanishing viscosity $\nu \to 0$ limit. We split the vorticity evolution into the free evolution (without a boundary) and a boundary corrector tha...
1909.07230v1
2019-10-19
Anomalies in the switching dynamics of C-type antiferromagnets and antiferromagnetic nanowires
Antiferromagnets (AFMs) are widely believed to be superior than ferromagnets in spintronics because of their high stability due to the vanishingly small stray field. It is thus expected that the order parameter of AFM should always align along the easy-axis of the crystalline anisotropy. In contrast to this conventiona...
1910.08668v1
2019-11-01
Importance of Giant Impact Ejecta for Orbits of Planets Formed during the Giant Impact Era
Terrestrial planets are believed to be formed via giant impacts of Mars-sized protoplanets. Planets formed via giant impacts have highly eccentric orbits. A swarm of planetesimals around the planets may lead to eccentricity damping for the planets via the equipartition of random energies (dynamical friction). However, ...
1911.00278v3
2019-11-06
Damping in Ru/Co-based multilayer films with large Dzyaloshinskii-Moriya interaction
Recent development of the magnetic material engineering led to achievement of the systems with a high interfacial Dzyaloshinskii-Moriya interaction (DMI). As a result, the formation of non-collinear magnetic soliton states or nonreciprocal spin wave dynamics is achievable. Typically used materials are based on bi-layer...
1911.02467v1
2019-11-14
Studies of the beam-ion instability and its mitigation with feedback system
The beam-ion interaction is a potential limitation of beam performance in electron accelerators, especially where the beam emittance is of a great concern in future ultra-low emittance light source. "Conventionally", the beam instability due to beam-ion interaction is attributed to two types of effects: ion trapping ef...
1911.05958v1
2019-12-05
Steering magnonic dynamics and permeability at exceptional points in a parity-time symmetric waveguide
Tuning the low-energy magnetic dynamics is a key element in designing novel magnetic metamaterials, spintronic devices and magnonic logic circuits. This study uncovers a new, highly effective way of controlling the magnetic permeability via shaping the magnonic properties in coupled magnetic waveguides separated by cur...
1912.02500v1
2020-01-23
Skyrmion Dynamics and Topological Sorting on Periodic Obstacle Arrays
We examine skyrmions under a dc drive interacting with a square array of obstacles for varied obstacle size and damping. When the drive is applied in a fixed direction, we find that the skyrmions are initially guided in the drive direction but also move transverse to the drive due to the Magnus force. The skyrmion Hall...
2001.08835v1
2020-03-06
Lattice dynamics and polarization-dependent phonon damping in $α$-phase FeSi$_{2}$ nanoislands
We determined the lattice dynamics of metastable, surface-stabilized $\alpha$-phase FeSi$_2$ nanoislands epitaxially grown on the Si(111) surface with average heights and widths ranging from 1.5 to 20 nm and 18 to 72 nm, respectively. The crystallographic orientation, surface morphology and local crystal structure of t...
2003.02969v1
2020-03-20
The resonant drag instability of dust streaming in turbulent protoplanetary disc
Damping of the previously discovered resonant drag instability (RDI) of dust streaming in protoplanetary disc is studied using the local approach to dynamics of gas-dust perturbations in the limit of the small dust fraction. Turbulence in a disc is represented by the effective viscosity and diffusivity in equations of ...
2003.09212v1
2020-05-22
Quasinormal modes, shadow and greybody factors of 5D electrically charged Bardeen black holes
We study quasinormal modes (QNMs) in 5D electrically charged Bardeen black holes spacetime by considering the scalar and electromagnetic field perturbations. The black holes spacetime is an exact solution of Einstein gravity coupled to nonlinear electrodynamics in five dimensions, which has nonsingular behavior. To cal...
2005.11080v2
2020-05-28
Spintronics meets nonadiabatic molecular dynamics: Geometric spin torque and damping on noncollinear classical magnetism due to electronic open quantum system
We analyze a quantum-classical hybrid system of steadily precessing slow classical localized magnetic moments, forming a head-to-head domain wall, embedded into an open quantum system of fast nonequilibrium electrons. The electrons reside within a metallic wire connected to macroscopic reservoirs. The model captures th...
2005.14153v2
2020-07-15
On the Extension of Linear Damping to Quantum Mechanics through Fractionary Momentum Operators Pt. I
The use of fractional momentum operators and fractionary kinetic energy used to model linear damping in dissipative systems such as resistive circuits and a spring-mass ensambles was extended to a quantum mechanical formalism. Three important associated 1 dimensional problems were solved: the free particle case, the in...
2007.07434v3
2020-07-18
Results from the Alfvén Eigenmode Active Diagnostic during the 2019-2020 JET deuterium campaign
This paper presents results of extensive analysis of mode excitation observed during the operation of the Alfv\'{e}n Eigenmode Active Diagnostic (AEAD) in the JET tokamak during the 2019-2020 deuterium campaign. Six of eight toroidally spaced antennas, each with independent power and phasing, were successful in activel...
2007.09412v1
2020-08-18
A Quasi-Linear Diffusion Model for Resonant Wave-Particle Instability in Homogeneous Plasma
In this paper, we develop a model to describe the generalized wave-particle instability in a quasi-neutral plasma. We analyze the quasi-linear diffusion equation for particles by expressing an arbitrary unstable and resonant wave mode as a Gaussian wave packet, allowing for an arbitrary direction of propagation with re...
2008.08169v2
2020-09-10
Spin waves in alloys at finite temperatures: application for FeCo magnonic crystal
We study theoretically the influence of the temperature and disorder on the spin wave spectrum of the magnonic crystal Fe$_{1-c}$Co$_{c}$. Our formalism is based on the analysis of a Heisenberg Hamiltonian by means of the wave vector and frequency dependent transverse magnetic susceptibility. The exchange integrals ent...
2009.04712v6
2020-09-14
On the response of a star cluster to a tidal perturbation
We study the response of star clusters to individual tidal perturbations using controlled $N$-body simulations. We consider perturbations by a moving point mass and by a disc, and vary the duration of the perturbation as well as the cluster density profile. For fast perturbations (i.e. `shocks'), the cluster gains ener...
2009.06643v2
2020-09-18
African Easterly Waves in an Idealized General Circulation Model: Instability and Wavepacket Diagnostics
We examine the group dynamic of African easterly waves (AEW) generated in a realistic, spatially non-homogeneous African easterly jet (AEJ) using an idealized general circulation model. Our objective is to investigate whether the limited zonal extent of the AEJ is an impediment to AEW development. We construct a series...
2009.08604v1
2020-09-25
Polaronic Contributions to Friction in a Manganite Thin Film
Despite the huge importance of friction in regulating movement in all natural and technological processes, the mechanisms underlying dissipation at a sliding contact are still a matter of debate. Attempts to explain the dependence of measured frictional losses at nanoscale contacts on the electronic degrees of freedom ...
2009.12137v1
2020-09-25
Direct computation of nonlinear mapping via normal form for reduced-order models of finite element nonlinear structures
The direct computation of the third-order normal form for a geometrically nonlinear structure discretised with the finite element (FE) method, is detailed. The procedure allows to define a nonlinear mapping in order to derive accurate reduced-order models (ROM) relying on invariant manifold theory. The proposed reducti...
2009.12145v1
2020-09-29
Structural Phase Dependent Giant Interfacial Spin Transparency in W/CoFeB Thin Film Heterostructure
Pure spin current has transfigured the energy-efficient spintronic devices and it has the salient characteristic of transport of the spin angular momentum. Spin pumping is a potent method to generate pure spin current and for its increased efficiency high effective spin-mixing conductance (Geff) and interfacial spin tr...
2009.14143v1
2020-10-08
Modeling of the ECCD injection effect on the Heliotron J and LHD plasma stability
The aim of the study is to analyze the stability of the Energetic Particle Modes (EPM) and Alfven Eigenmodes (AE) in Helitron J and LHD plasma if the electron cyclotron current drive (ECCD) is applied. The analysis is performed using the code FAR3d that solves the reduced MHD equations describing the linear evolution o...
2010.03892v1
2020-10-08
A blow-up result for the wave equation with localized initial data: the scale-invariant damping and mass term with combined nonlinearities
We are interested in this article in studying the damped wave equation with localized initial data, in the \textit{scale-invariant case} with mass term and two combined nonlinearities. More precisely, we consider the following equation: $$ (E) {1cm} u_{tt}-\Delta u+\frac{\mu}{1+t}u_t+\frac{\nu^2}{(1+t)^2}u=|u_t|^p+|u|^...
2010.05455v1
2020-10-14
Kink Oscillations in Solar Coronal Loops with Elliptical Cross-Sections. I. the linear regime
The cross sections of solar coronal loops are suggested to be rarely circular. We examine linear kink oscillations in straight, density-enhanced, magnetic cylinders with elliptical cross-sections by solving the three-dimensional magnetohydrodynamic equations from an initial-value-problem perspective. Motivated by relev...
2010.06991v1
2020-11-04
The impact of astrophysical dust grains on the confinement of cosmic rays
We argue that charged dust grains could significantly impact the confinement and transport of galactic cosmic rays. For sub-GeV to ~1000GeV cosmic rays, small-scale parallel Alfv\'en waves, which isotropize cosmic rays through gyro-resonant interactions, are also gyro-resonant with charged grains. If the dust is nearly...
2011.02497v2
2020-11-17
A Phase Resonance Approach for Modal Testing of Structures with Nonlinear Dissipation
The concept of nonlinear modes is useful for the dynamical characterization of nonlinear mechanical systems. While efficient and broadly applicable methods are now available for the computation of nonlinear modes, nonlinear modal testing is still in its infancy. The purpose of this work is to overcome its present limit...
2011.08500v1
2020-12-08
Meta Learning-based MIMO Detectors: Design, Simulation, and Experimental Test
Deep neural networks (NNs) have exhibited considerable potential for efficiently balancing the performance and complexity of multiple-input and multiple-output (MIMO) detectors. We propose a receiver framework that enables efficient online training by leveraging the following simple observation: although NN parameters ...
2012.04379v1
2020-12-31
Adaptive Surgical Robotic Training Using Real-Time Stylistic Behavior Feedback Through Haptic Cues
Surgical skill directly affects surgical procedure outcomes; thus, effective training is needed to ensure satisfactory results. Many objective assessment metrics have been developed and some are widely used in surgical training simulators. These objective metrics provide the trainee with descriptive feedback about thei...
2101.00097v3
2021-01-08
Damped dust-ion-acoustic solitons in collisional magnetized nonthermal plasmas
A multi-species magnetized collisional nonthermal plasma system containing inertial ion species, non-inertial electron species following nonthermal $\kappa-$ distribution, and immobile dust particles, is considered to examine the characteristics of the dissipative dust-ion-acoustic (DIA) soliton modes, \textbf{theoreti...
2101.03183v2
2020-12-28
Global complexity effects due to local damping in a nonlinear system in 1:3 internal resonance
It is well-known that nonlinearity may lead to localization effects and coupling of internally resonant modes. However, research focused primarily on conservative systems commonly assumes that the near-resonant forced response closely follows the autonomous dynamics. Our results for even a simple system of two coupled ...
2101.03233v1
2021-01-27
New estimations of the added mass and damping of two cylinders vibrating in a viscous fluid, from theoretical and numerical approaches
This paper deals with the small oscillations of two circular cylinders immersed in a viscous stagnant fluid. A new theoretical approach based on an Helmholtz expansion and a bipolar coordinate system is presented to estimate the fluid forces acting on the two bodies. We show that these forces are linear combinations of...
2101.11346v1
2021-03-08
A Self-Consistent, Time-Dependent Treatment of Dynamical Friction: New Insights regarding Core Stalling and Dynamical Buoyancy
Dynamical friction is typically regarded a secular process, in which the subject ('perturber') evolves very slowly (secular approximation), and has been introduced to the host over a long time (adiabatic approximation). These assumptions imply that dynamical friction arises from the LBK torque with non-zero contributio...
2103.05004v1
2021-04-10
Non-Markovian open quantum system approach to the early universe: I. Damping of gravitational waves by matter
By revising the application of the open quantum system approach to the early universe and extending it to the conditions beyond the Markovian approximation, we obtain a new non-Markovian quantum Boltzmann equation. Throughout the paper, we also develop an extension of the quantum Boltzmann equation to describe the proc...
2104.04836v2
2021-04-19
Giant spin-orbit torque efficiency in all-epitaxial heterostructures
A large anti-damping spin-obit torque (SOT) efficiency in magnetic heterostructures is a prerequisite to realize energy efficient spin torque based magnetic memories and logic devices. The efficiency can be characterized in terms of the spin-orbit fields generated by anti-damping torques when an electric current is pas...
2104.09168v1