publicationDate
stringlengths
1
2.79k
title
stringlengths
1
36.5k
abstract
stringlengths
1
37.3k
id
stringlengths
9
47
2021-11-20
Skyrmionics in correlated oxides
While chiral magnets, metal-based magnetic multilayers, or Heusler compounds have been considered as the material workhorses in the field of skyrmionics, oxides are now emerging as promising alternatives, as they host special correlations between the spin-orbital-charge-lattice degrees of freedom and/or coupled ferroic...
2111.10562v2
2021-12-01
Unconditional well-posedness and IMEX improvement of a family of predictor-corrector methods in micromagnetics
Recently, Kim & Wilkening (Convergence of a mass-lumped finite element method for the Landau-Lifshitz equation, Quart. Appl. Math., 76, 383-405, 2018) proposed two novel predictor-corrector methods for the Landau-Lifshitz-Gilbert equation (LLG) in micromagnetics, which models the dynamics of the magnetization in ferrom...
2112.00451v1
2021-12-21
Fast long-wavelength exchange spin waves in partially-compensated Ga:YIG
Spin waves in yttrium iron garnet (YIG) nano-structures attract increasing attention from the perspective of novel magnon-based data processing applications. For short wavelengths needed in small-scale devices, the group velocity is directly proportional to the spin-wave exchange stiffness constant $\lambda_\mathrm{ex}...
2112.11348v1
2022-01-27
Magnon transport and thermoelectric effects in ultrathin Tm3Fe5O12/Pt nonlocal devices
The possibility of electrically exciting and detecting magnon currents in magnetic insulators has opened exciting perspectives for transporting spin information in electronic devices. However, the role of the magnetic field and the nonlocal thermal gradients on the magnon transport remain unclear. Here, by performing n...
2201.11353v1
2022-01-31
Tuning spin-orbit torques across the phase transition in VO$_2$/NiFe heterostructure
The emergence of spin-orbit torques as a promising approach to energy-efficient magnetic switching has generated large interest in material systems with easily and fully tunable spin-orbit torques. Here, current-induced spin-orbit torques in VO$_2$/NiFe heterostructures were investigated using spin-torque ferromagnetic...
2201.12984v1
2022-02-03
Controlling spin pumping into superconducting Nb by proximity-induced spin-triplet Cooper pairs
Proximity-induced long-range spin-triplet supercurrents, important for the field of superconducting spintronics, are generated in superconducting/ferromagnetic heterostructures when interfacial magnetic inhomogeneities responsible for spin mixing and spin flip scattering are present. The multilayer stack Nb/Cr/Fe/Cr/Nb...
2202.01520v1
2022-06-17
Multiscale Modelling of the Antiferromagnet Mn2Au: From ab-initio to Micromagnetics
Antiferromagnets (AFMs) are strong candidates for the future spintronic and memory applications largely because of their inherently fast dynamics and lack of stray fields, with Mn2Au being one of the most promising. For the numerical modelling of magnetic material properties, it is common to use ab-initio methods, atom...
2206.08625v1
2022-10-29
Micromagnetic frequency-domain simulation methods for magnonic systems
We present efficient numerical methods for the simulation of small magnetization oscillations in three-dimensional micromagnetic systems. Magnetization dynamics is described by the Landau-Lifshitz-Gilbert (LLG) equation, linearized in the frequency domain around a generic equilibrium configuration, and formulated in a ...
2210.16564v3
2023-03-07
Magnon currents excited by the spin Seebeck effect in ferromagnetic EuS thin films
A magnetic insulator is an ideal platform to propagate spin information by exploiting magnon currents. However, until now, most studies have focused on Y$_3$Fe$_5$O$_{12}$ (YIG) and a few other ferri- and antiferromagnetic insulators, but not on pure ferromagnets. In this study, we demonstrate for the first time that m...
2303.03833v2
2023-04-01
A coupled magneto-structural continuum model for multiferroic $\mathrm{BiFeO}_3$
A continuum approach to study magnetoelectric multiferroic $\mathrm{BiFeO}_3$ (BFO) is proposed. Our modeling effort marries the ferroelectric (FE) phase field method and micromagnetic simulations in order to describe the entire multiferroic order parameter sector (polarization, oxygen antiphase tilts, strain, and magn...
2304.00270v1
2023-09-18
Coherent Tunneling and Strain Sensitivity of an All Heusler Alloy Magnetic Tunneling Junction: A First-Principles Study
Half-metallic Co-based full Heusler alloys have captured considerable attention of the researchers in the realm of spintronic applications, owing to their remarkable characteristics such as exceptionally high spin polarization at Fermi level, ultra-low Gilbert damping, and high Curie temperature. In this comprehensive ...
2309.09755v1
2023-10-27
Effect of interfacial Dzyaloshinskii-Moriya interaction in spin dynamics of an Antiferromagnet coupled Ferromagnetic double-barrier Magnetic Tunnel Junction
In this work, we have studied the spin dynamics of a synthethic Antiferromagnet (SAFM)$|$Heavy Metal (HM)$|$Ferromagnet (FM) double barrier magnetic tunnel junction (MTJ) in presence of Ruderman-Kittel-Kasuya-Yoside interaction (RKKYI), interfacial Dzyaloshinskii-Moriya interaction (iDMI), N\'eel field and Spin-Orbit C...
2310.18175v1
2023-11-14
Berry curvature induced giant intrinsic spin-orbit torque in single layer magnetic Weyl semimetal thin films
Topological quantum materials can exhibit unconventional surface states and anomalous transport properties, but their applications to spintronic devices are restricted as they require the growth of high-quality thin films with bulk-like properties. Here, we study 10--30 nm thick epitaxial ferromagnetic Co$_{\rm 2}$MnGa...
2311.08145v2
2023-12-26
All solution grown epitaxial magnonic crystal of thulium iron garnet thin film
Magnonics has shown the immense potential of compatibility with CMOS devices and the ability to be utilized in futuristic quantum computing. Therefore, the magnonic crystals, both metallic and insulating, are under extensive exploration. The presence of high spin-orbit interaction induced by the presence of rare-earth ...
2312.15973v1
2024-03-01
Spin current control of magnetism
Exploring novel strategies to manipulate the order parameter of magnetic materials by electrical means is of great importance, not only for advancing our understanding of fundamental magnetism, but also for unlocking potential practical applications. A well-established concept to date uses gate voltages to control magn...
2403.00709v1
2004-04-06
Bounds for contractive semigroups and second order systems
We derive a uniform bound for the difference of two contractive semigroups, if the difference of their generators is form-bounded by the Hermitian parts of the generators themselves. We construct a semigroup dynamics for second order systems with fairly general operator coefficients and apply our bound to the perturbat...
0404120v1
1998-05-29
Magnetic Faraday-Instability
In a magnetic fluid parametrically driven surface waves can be excited by an external oscillating magnetic field. A static magnetic field changes the restoring forces and damping coefficients of the various surface waves. This property enables the excitation of both subharmonic and harmonic responses of the standing wa...
9806001v1
2003-12-10
Charge Fluctuation of Dust Grains and its Impact on Dusty Wave Propagation
In this paper we consider the influence of dust charge fluctuations on damping of the dust-ion-acoustic waves. Fluid approximation of longitudinal electrostatic waves in unmagnetized plasmas is considered. We show that for a weak acoustic wave the attenuation depends on a phenomenological charging coefficient.
0312067v1
2005-07-26
On simulations of the classical harmonic oscillator equation by difference equations
We show that any second order linear ordinary diffrential equation with constant coefficients (including the damped and undumped harmonic oscillator equation) admits an exact discretization, i.e., there exists a difference equation whose solutions exactly coincide with solutions of the corresponding differential equati...
0507182v1
1998-02-16
Classical states via decoherence
The initial states which minimize the predictability loss for a damped harmonic oscillator are identified as quasi-free states with a symmetry dictated by the environment's diffusion coefficients. For an isotropic diffusion in phase space, coherent states (or mixtures of coherent states) are selected as the most stable...
9802044v1
2007-11-15
$C^m$-theory of damped wave equations with stabilisation
The aim of this note is to extend the energy decay estimates from [J. Wirth, J. Differential Equations 222 (2006) 487--514] to a broader class of time-dependent dissipation including very fast oscillations. This is achieved using stabilisation conditions on the coefficient in the spirit of [F. Hirosawa, Math. Ann. 339/...
0711.2403v1
2014-04-22
A unique continuation result for the plate equation and an application
In this paper, we prove the unique continuation property for the weak solution of the plate equation with non-smooth coefficients. Then, we apply this result to study the global attractor for the semilinear plate equation with a localized damping.
1404.5586v3
2017-09-24
Exceptional points in two simple textbook examples
We propose to introduce the concept of exceptional points in intermediate courses on mathematics and classical mechanics by means of simple textbook examples. The first one is an ordinary second-order differential equation with constant coefficients. The second one is the well known damped harmonic oscillator. They ena...
1710.00067v1
2019-06-06
Well-posedness and exponential decay estimates for a Korteweg-de Vries-Burgers equation with time-delay
We consider the KdV-Burgers equation and its linear version in presence of a delay feedback. We prove well-posedness of the models and exponential decay estimates under appropriate conditions on the damping coefficients. Our arguments rely on a Lyapunov functional approach combined with a step by step procedure and sem...
1906.02488v1
2021-07-21
Convergence rates for the Heavy-Ball continuous dynamics for non-convex optimization, under Polyak-Łojasiewicz condition
We study convergence of the trajectories of the Heavy Ball dynamical system, with constant damping coefficient, in the framework of convex and non-convex smooth optimization. By using the Polyak-{\L}ojasiewicz condition, we derive new linear convergence rates for the associated trajectory, in terms of objective functio...
2107.10123v2
2021-08-29
Well-posedness and stability for semilinear wave-type equations with time delay
In this paper we analyze a semilinear abstract damped wave-type equation with time delay. We assume that the delay feedback coefficient is variable in time and belonging to $L^1_{loc}([0, +\infty)).$ Under suitable assumptions, we show well-posedness and exponential stability for small initial data. Our strategy combin...
2108.12786v1
2021-10-22
p-Laplacian wave equations in non-cylindrical domains
This paper is devoted to studying the stability of p-Laplacian wave equations with strong damping in non-cylindrical domains. The method of proof based on some estimates for time-varying coefficients rising from moving boundary and a modified Kormonik inequality. Meanwhile, by selecting appropriate auxiliary functions,...
2110.11547v1
2022-07-25
Inviscid limit for the compressible Navier-Stokes equations with density dependent viscosity
We consider the compressible Navier-Stokes system describing the motion of a barotropic fluid with density dependent viscosity confined in a three-dimensional bounded domain $\Omega$. We show the convergence of the weak solution to the compressible Navier-Stokes system to the strong solution to the compressible Euler s...
2207.12222v1
2018-05-08
Effect of transport coefficients on excitation of flare-induced standing slow-mode waves in coronal loops
Standing slow-mode waves have been recently observed in flaring loops by the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO). By means of the coronal seismology technique transport coefficients in hot ($\sim$10 MK) plasma were determined by Wang et al.(2015, Paper I), revealing that thermal c...
1805.03282v1
2005-01-02
Effect of dipolar interactions on the magnetization of a cubic array of nanomagnets
We investigated the effect of intermolecular dipolar interactions on a cubic 3D ensemble of 5X5X4=100 nanomagnets, each with spin $S = 5$. We employed the Landau-Lifshitz-Gilbert equation to solve for the magnetization $M(B)$ curves for several values of the damping constant $\alpha$, the induction sweep rate, the latt...
0501006v2
2019-03-07
Uniaxial anisotropy, intrinsic and extrinsic damping in Co$_{2}$FeSi Heusler alloy thin films
Ferromagnetic resonance (FMR) technique has been used to study the magnetization relaxation processes and magnetic anisotropy in two different series of the Co2FeSi (CFS) Heusler alloy thin films, deposited on the Si(111) substrate by UHV sputtering. While the CFS films of fixed (50 nm) thickness, deposited at differen...
1903.02976v1
2023-09-19
Impact of strain on the SOT-driven dynamics of thin film Mn$_3$Sn
Mn$_3$Sn, a metallic antiferromagnet with an anti-chiral 120$^\circ$ spin structure, generates intriguing magneto-transport signatures such as a large anomalous Hall effect, spin-polarized current with novel symmetries, anomalous Nernst effect, and magneto-optic Kerr effect. When grown epitaxially as MgO(110)[001]$\par...
2309.10246v2
2009-04-16
Good Concatenated Code Ensembles for the Binary Erasure Channel
In this work, we give good concatenated code ensembles for the binary erasure channel (BEC). In particular, we consider repeat multiple-accumulate (RMA) code ensembles formed by the serial concatenation of a repetition code with multiple accumulators, and the hybrid concatenated code (HCC) ensembles recently introduced...
0904.2482v1
2004-08-10
Cosmic Ray Scattering and Streaming in Compressible Magnetohydrodynamic Turbulence
Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call for revisions in the picture of cosmic ray transport. In this paper we use recently obtained scaling laws for MHD modes to obtain the scattering frequency for cosmic rays. Using quasilinear theory we calculate gyroresonance with MHD modes (Al...
0408172v1
1999-11-22
Two-fluid hydrodynamics of a Bose gas including damping from normal fluid transport coefficients
We extend our recent work on the two-fluid hydrodynamics of the condensate and non-condensate in a trapped Bose gas by including the dissipation associated with viscosity and thermal conduction. For purposes of illustration, we consider the hydrodynamic modes in the case of a uniform Bose gas. A finite thermal conducti...
9911336v1
2001-11-14
Soliton-radiation coupling in the parametrically driven, damped nonlinear Schrödinger equation
We use the Riemann-Hilbert problem to study the interaction of the soliton with radiation in the parametrically driven, damped nonlinear Schr\"odinger equation. The analysis is reduced to the study of a finite-dimensional dynamical system for the amplitude and phase of the soliton and the complex amplitude of the long-...
0111034v1
1996-12-08
Towards a Simple Model of Compressible Alfvenic Turbulence
A simple model collisionless, dissipative, compressible MHD (Alfvenic) turbulence in a magnetized system is investigated. In contrast to more familiar paradigms of turbulence, dissipation arises from Landau damping, enters via nonlinearity, and is distributed over all scales. The theory predicts that two different regi...
9612005v2
2009-01-15
The sound damping constant for generalized theories of gravity
The near-horizon metric for a black brane in Anti-de Sitter (AdS) space and the metric near the AdS boundary both exhibit hydrodynamic behavior. We demonstrate the equivalence of this pair of hydrodynamic systems for the sound mode of a conformal theory. This is first established for Einstein's gravity, but we then sho...
0901.2191v1
2009-07-30
Gas damping force noise on a macroscopic test body in an infinite gas reservoir
We present a simple analysis of the force noise associated with the mechanical damping of the motion of a test body surrounded by a large volume of rarefied gas. The calculation is performed considering the momentum imparted by inelastic collisions against the sides of a cubic test mass, and for other geometries for wh...
0907.5375v2
2011-03-08
Steady states of the parametric rotator and pendulum
We discuss several steady-state rotation and oscillation modes of the planar parametric rotator and pendulum with damping. We consider a general elliptic trajectory of the suspension point for both rotator and pendulum, for the latter at an arbitrary angle with gravity, with linear and circular trajectories as particul...
1103.1413v1
2011-03-28
Motion of position-dependent mass as a damping-antidamping process: Application to the Fermi gas and to the Morse potential
The object of this paper is to investigate, classically and quantum mechanically, the relation existing between the position-dependent effective mass and damping-antidamping dynamics. The quantization of the equations of motion is carried out using the geometric interpretation of the motion, and we compare it with the ...
1103.5440v3
2011-06-22
Tunable Magnonic Frequency and Damping in [Co/Pd]8 Multilayers with Variable Co Layer Thickness
We report the experimental observation of collective picosecond magnetization dynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy. The precession frequency shows large and systematic variation from about 5 GHz to about 90 GHz with the decrease in the Co layer thickness from 1.0 nm to 0.22 nm due to ...
1106.4491v1
2012-05-14
Critical viscoelastic response in jammed solids
We determine the linear viscoelastic response of jammed packings of athermal repulsive viscous spheres, a model for emulsions, wet foams, and soft colloidal suspensions. We numerically measure the complex shear modulus, a fundamental characterization of the response, and demonstrate that low frequency response displays...
1205.2960v1
2012-10-04
Basic microscopic plasma physics unified and simplified by N-body classical mechanics
Debye shielding, collisional transport, Landau damping of Langmuir waves, and spontaneous emission of these waves are introduced, in typical plasma physics textbooks, in different chapters. This paper provides a compact unified introduction to these phenomena without appealing to fluid or kinetic models, but by using N...
1210.1546v2
2015-01-23
Response solutions for quasi-periodically forced, dissipative wave equations
We consider several models of nonlinear wave equations subject to very strong damping and quasi-periodic external forcing. This is a singular perturbation, since the damping is not the highest order term. We study the existence of response solutions (i.e., quasi-periodic solutions with the same frequency as the forcing...
1501.05979v1
2015-05-08
Existence and general stabilization of the Timoshenko system with a thermo-viscoelastic damping and a delay term in the internal feedback
In this paper, we consider a Timoshenko system with a thermo-viscoelastic damping and a delay term in the internal feedback together with initial datum and boundary conditions of Dirichlet type, where g is a positive non-increasing relaxation function and {\mu}1, {\mu}2 are positive constants. Under an hypothesis betwe...
1505.01899v1
2015-09-03
Stability analysis of degenerately-damped oscillations
Presented here is a study of well-posedness and asymptotic stability of a "degenerately damped" PDE modeling a vibrating elastic string. The coefficient of the damping may vanish at small amplitudes thus weakening the effect of the dissipation. It is shown that the resulting dynamical system has strictly monotonically ...
1509.00917v1
2016-07-20
Envelope equation for the linear and nonlinear propagation of an electron plasma wave, including the effects of Landau damping, trapping, plasma inhomogeneity, and the change in the state of wave
This paper addresses the linear and nonlinear three-dimensional propagation of an electron wave in a collisionless plasma that may be inhomogeneous, nonstationary, anisotropic and even weakly magnetized. The wave amplitude, together with any hydrodynamic quantity characterizing the plasma (density, temperature,...) are...
1607.05844v2
2017-04-07
Underdamped stochastic harmonic oscillator
We investigate stationary states of the linear damped stochastic oscillator driven by L\'evy noises. In the long time limit kinetic and potential energies of the oscillator do not fulfill the equipartition theorem and their distributions follow the power-law asymptotics. At the same time, partition of the mechanical en...
1704.02119v2
2017-08-30
Convergence to diffusion waves for solutions of Euler equations with time-depending damping on quadrant
This paper is concerned with the asymptotic behavior of the solution to the Euler equations with time-depending damping on quadrant $(x,t)\in \mathbb{R}^+\times\mathbb{R}^+$, \begin{equation}\notag \partial_t v - \partial_x u=0, \qquad \partial_t u + \partial_x p(v) =\displaystyle -\frac{\alpha}{(1+t)^\lamb...
1708.09127v1
2018-01-23
The effect of liquid on the vibrational intensity of a wineglass at steady state resonance
As a liquid is inserted into a wineglass, the natural frequency of the wineglass decreases. This phenomenon, known as pitch lowering, is well explained in past papers. However, previous literature have not yet mentioned that pitch lowering also reduces the resonance intensity of a wineglass. Thus, this present paper ai...
1801.07514v5
2018-04-11
A global existence result for a semilinear wave equation with scale-invariant damping and mass in even space dimension
In the present article a semilinear wave equation with scale-invariant damping and mass is considered. The global (in time) existence of radial symmetric solutions in even spatial dimension $n$ is proved using weighted $L^\infty-L^\infty$ estimates, under the assumption that the multiplicative constants, which appear i...
1804.03978v1
2018-07-17
Boundary-to-Displacement Asymptotic Gains for Wave Systems With Kelvin-Voigt Damping
We provide estimates for the asymptotic gains of the displacement of a vibrating string with endpoint forcing, modeled by the wave equation with Kelvin-Voigt and viscous damping and a boundary disturbance. Two asymptotic gains are studied: the gain in the L2 spatial norm and the gain in the spatial sup norm. It is show...
1807.06549v1
2018-07-24
Stabilization of an unstable wave equation using an infinite dimensional dynamic controller
This paper deals with the stabilization of an anti-stable string equation with Dirichlet actuation where the instability appears because of the uncontrolled boundary condition. Then, infinitely many unstable poles are generated and an infinite dimensional control law is therefore proposed to exponentially stabilize the...
1807.08999v2
2018-08-30
The influence of the coefficients of a system of coupled wave equations with fractional damping on its stabilization
In this work, we consider a system of two wave equations coupled by velocities in one-dimensional space, with one boundary fractional damping. First, we show that the system is strongly asymptotically stable if and only if the coupling parameter b of the two equations is outside a discrete set of exceptional real value...
1808.10285v4
2019-06-10
Global existence of weak solutions to the compressible quantum Navier-Stokes equations with degenerate viscosity
We study the compressible quantum Navier-Stokes (QNS) equations with degenerate viscosity in the three dimensional periodic domains. On the one hand, we consider QNS with additional damping terms. Motivated by the recent works [Li-Xin, arXiv:1504.06826] and [Antonelli-Spirito, Arch. Ration. Mech. Anal., 203(2012), 499-...
1906.03971v1
2019-08-19
Time Delay in the Swing Equation: A Variety of Bifurcations
The present paper addresses the swing equation with additional delayed damping as an example for pendulum-like systems. In this context, it is proved that recurring sub- and supercritical Hopf bifurcations occur if time delay is increased. To this end, a general formula for the first Lyapunov coefficient in second orde...
1908.07996v3
2019-12-30
A Link Between Relativistic Rest Energy and Fractionary Momentum Operators of Order 1/2
The solution of a causal fractionary wave equation in an infinite potential well was obtained. First, the so-called "free particle" case was solved, giving as normalizable solutions a superposition of damped oscillations similar to a wave packet. From this results, the infinite potential well case was then solved. The ...
1912.12770v4
2020-08-18
Singularity formation for compressible Euler equations with time-dependent damping
In this paper, we consider the compressible Euler equations with time-dependent damping \frac{\a}{(1+t)^\lambda}u in one space dimension. By constructing 'decoupled' Riccati type equations for smooth solutions, we provide some sufficient conditions under which the classical solutions must break down in finite time. As ...
2008.07756v1
2020-11-14
Learning a Reduced Basis of Dynamical Systems using an Autoencoder
Machine learning models have emerged as powerful tools in physics and engineering. Although flexible, a fundamental challenge remains on how to connect new machine learning models with known physics. In this work, we present an autoencoder with latent space penalization, which discovers finite dimensional manifolds und...
2011.07346v1
2021-01-11
Damped (linear) response theory within the resolution-of-identity coupled cluster singles and approximate doubles (RI-CC2) method
An implementation of a complex solver for the solution of the response equations required to compute the complex response functions of damped response theory is presented for the resolution-of-identity (RI) coupled-cluster singles and approximate doubles CC2 method. The implementation uses a partitioned formulation tha...
2101.03756v1
2021-06-24
Landau damping of electron-acoustic waves due to multi-plasmon resonances
The linear and nonlinear theories of electron-acoustic waves (EAWs) are studied in a partially degenerate quantum plasma with two-temperature electrons and stationary ions. The initial equilibrium of electrons is assumed to be given by the Fermi-Dirac distribution at finite temperature. By employing the multi-scale asy...
2106.12754v2
2021-08-12
The damping and diffusion of atoms moving in the background electromagnetic environment
The interaction between an atom and the quantized electromagnetic field depends on the position of the atom. Then the atom experiences a force which is the minus gradient of this interaction. Through the Heisenberg equations of motion and the Born-Markov approximation, the mean and correlation of the force are obtained...
2108.05590v3
2021-11-18
Sharp Stability of a String with Local Degenerate Kelvin-Voigt Damping
This paper is on the asymptotic behavior of the elastic string equation with localized degenerate Kelvin--Voigt damping $$ u_{tt}(x,t)-[u_{x}(x,t)+b(x)u_{x,t}(x,t)]_{x}=0,\; x\in(-1,1),\; t>0,$$ where $b(x)=0$ on $x\in (-1,0]$, and $b(x)=x^\alpha>0$ on $x\in (0,1)$ for $\alpha\in(0,1)$. It is known that the optimal dec...
2111.09500v1
2021-11-26
Damping of Pseudo-Goldstone Fields
Approximate symmetries abound in Nature. If these symmetries are also spontaneously broken, the would-be Goldstone modes acquire a small mass, or inverse correlation length, and are referred to as pseudo-Goldstones. At nonzero temperature, the effects of dissipation can be captured by hydrodynamics at sufficiently long...
2111.13459v2
2023-06-26
Blow-up result for a weakly coupled system of wave equations with a scale-invariant damping, mass term and time derivative nonlinearity
We study in this article the blow-up of solutions to a coupled semilinear wave equations which are characterized by linear damping terms in the \textit{scale-invariant regime}, time-derivative nonlinearities, mass terms and Tricomi terms. The latter are specifically of great interest from both physical and mathematical...
2306.14768v1
2010-03-11
Damping of MHD turbulence in partially ionized gas and the observed difference of velocities of neutrals and ions
Theoretical and observational studies on the turbulence of the interstellar medium developed fast in the past decades. The theory of supersonic magnetized turbulence, as well as the understanding of projection effects of observed quantities, are still in progress. In this work we explore the characterization of the tur...
1003.2346v1
2012-11-06
Torsional Alfvén waves in solar partially ionized plasma: effects of neutral helium and stratification
Ion-neutral collisions may lead to the damping of Alfven waves in chromospheric and prominence plasmas. Neutral helium atoms enhance the damping in certain temperature interval, where the ratio of neutral helium and neutral hydrogen atoms is increased. Therefore, the height-dependence of ionization degrees of hydrogen ...
1211.1348v2
1999-05-29
Theory of Hall Effect and Electrical Transport in High-Tc Cuprates: Effects of Antiferromagnetic Spin Fluctuations
In the normal state of high-Tc cuprates, the Hall coefficient shows remarkable temperature dependence, and its absolute value is enhanced in comparison with that value simply estimated on the basis of band structure. It has been recognized that this temperature dependence of the Hall coefficient is due to highly anisot...
9905428v1
2021-06-02
In-medium kinetic theory of $D$ mesons and heavy-flavor transport coefficients
We extend the kinetic theory of $D$ mesons to accommodate thermal and off-shell effects due to the medium modification of the heavy-meson spectral functions. From the Kadanoff-Baym approach we derive the off-shell Fokker-Planck equation which encodes the heavy-flavor transport coefficients. We analyze the thermal width...
2106.01156v2
2022-04-08
Transport coefficients of heavy quarkonia comparing with heavy quark coefficients
We revisit the transport coefficients of heavy quarkonia moving in high-temperature QCD plasmas. The thermal width and mass shift for heavy quarkonia are closely related to the momentum diffusion coefficient and its dispersive counterpart for heavy quarks, respectively. For quarkonium at rest in plasmas the longitudina...
2204.04180v1
2006-06-15
Purity and decoherence in the theory of a damped harmonic oscillator
For the generalized master equations derived by Karrlein and Grabert for the microscopic model of a damped harmonic oscillator, the conditions for purity of states are written, in particular for different initial conditions and different types of damping, including Ohmic, Drude and weak coupling cases, Agarwal and Weid...
0606134v1
2009-10-09
One-way coupled Van der Pol system
The equation of the Van der Pol oscillator, being characterized by a dissipative term, is non-Lagrangian. Appending an additional degree of freedom we bring the equation in the frame of action principle and thus introduce a one-way coupled system. As with the Van der Pol oscillator, the coupled system also involves onl...
0910.1700v1
2018-02-18
On energy stable discontinuous Galerkin spectral element approximations of the perfectly matched layer for the wave equation
We develop a provably energy stable discontinuous Galerkin spectral element method (DGSEM) approximation of the perfectly matched layer (PML) for the three and two space dimensional (3D and 2D) linear acoustic wave equations, in first order form, subject to well-posed linear boundary conditions. First, using the well-k...
1802.06388v1
2018-09-19
Critical exponent for the semilinear wave equations with a damping increasing in the far field
We consider the Cauchy problem of the semilinear wave equation with a damping term \begin{align*} u_{tt} - \Delta u + c(t,x) u_t = |u|^p, \quad (t,x)\in (0,\infty)\times \mathbb{R}^N,\quad u(0,x) = \varepsilon u_0(x), \ u_t(0,x) = \varepsilon u_1(x), \quad x\in \mathbb{R}^N, \end{align*} where $p>1$ and the coeffic...
1809.06994v1
2020-08-03
Improvement on the blow-up of the wave equation with the scale-invariant damping and combined nonlinearities
We consider in this article the damped wave equation, in the \textit{scale-invariant case} with combined two nonlinearities, which reads as follows: \begin{displaymath} \d (E) \hspace{1cm} u_{tt}-\Delta u+\frac{\mu}{1+t}u_t=|u_t|^p+|u|^q, \quad \mbox{in}\ \R^N\times[0,\infty), \end{displaymath} with small initial data....
2008.02109v3
2021-07-17
Theoretical and numerical study of vibrational resonance in a damped softening Duffing oscillator
We study the possibility of occurrence of vibrational resonance in a softening Duffing oscillator in the underdamped and overdamped cases both theoretically as well as numerically. The oscillator is driven by two periodic forces. Numerically we find that in the underdamped case two oscillatory solutions are obtained in...
2107.08302v1
2021-11-15
Convergence Analysis of A Second-order Accurate, Linear Numerical Scheme for The Landau-Lifshitz Equation with Large Damping Parameters
A second order accurate, linear numerical method is analyzed for the Landau-Lifshitz equation with large damping parameters. This equation describes the dynamics of magnetization, with a non-convexity constraint of unit length of the magnetization. The numerical method is based on the second-order backward differentiat...
2111.07537v1
2022-12-22
Spin wave dispersion of ultra-low damping hematite ($α\text{-Fe}_2\text{O}_3$) at GHz frequencies
Low magnetic damping and high group velocity of spin waves (SWs) or magnons are two crucial parameters for functional magnonic devices. Magnonics research on signal processing and wave-based computation at GHz frequencies focussed on the artificial ferrimagnetic garnet Y$_3$Fe$_5$O$_{12}$ (YIG) so far. We report on spi...
2212.11887v2
2024-02-19
Global existence for non-homogeneous incompressible inviscid fluids in presence of Ekman pumping
In this paper, we study the global solvability of the density-dependent incompressible Euler equations, supplemented with a damping term of the form $ \mathfrak{D}_{\alpha}^{\gamma}(\rho, u) = \alpha \rho^{\gamma} u $, where $\alpha>0$ and $ \gamma \in \{0,1\} $. To some extent, this system can be seen as a simplified ...
2402.12592v1
1993-04-01
Wavelet transforms versus Fourier transforms
This note is a very basic introduction to wavelets. It starts with an orthogonal basis of piecewise constant functions, constructed by dilation and translation. The ``wavelet transform'' maps each $f(x)$ to its coefficients with respect to this basis. The mathematics is simple and the transform is fast (faster than the...
9304214v1
2008-01-07
Magnetization reversal driven by spin-injection : a mesoscopic spin-transfer effect
A mesoscopic description of spin-transfer effect is proposed, based on the spin-injection mechanism occurring at the junction with a ferromagnet. The effect of spin-injection is to modify locally, in the ferromagnetic configuration space, the density of magnetic moments. The corresponding gradient leads to a current-de...
0801.1019v1
2012-07-24
Bulk Topological Invariants in Noninteracting Point Group Symmetric Insulators
We survey various quantized bulk physical observables in two- and three-dimensional topological band insulators invariant under translational symmetry and crystallographic point group symmetries (PGS). In two-dimensional insulators, we show that: (i) the Chern number of a $C_n$-invariant insulator can be determined, up...
1207.5767v2
2016-08-06
High current, high efficiency graded band gap perovskite solar cells
Organic-inorganic halide perovskite materials have emerged as attractive alternatives to conventional solar cell building blocks. Their high light absorption coefficients and long diffusion lengths suggest high power conversion efficiencies (PCE),1-5 and indeed perovskite-based single band gap and tandem solar cell des...
1608.02150v1
2016-08-30
LiRa: A New Likelihood-Based Similarity Score for Collaborative Filtering
Recommender system data presents unique challenges to the data mining, machine learning, and algorithms communities. The high missing data rate, in combination with the large scale and high dimensionality that is typical of recommender systems data, requires new tools and methods for efficient data analysis. Here, we a...
1608.08646v2
2018-11-01
Time Quantified Monte Carlo Method for Long-range Interacting Systems
We propose a method for simulating the stochastic dynamics of classical spin systems with long-range interactions. The method incorporates the stochastic cutoff (SCO) method, which is originally specialized for simulating equilibrium state, into time quantified Monte Carlo (TQMC) method. We analytically prove that the ...
1811.00237v2
2019-01-10
Multi-Parameter Regression Survival Modelling: An Alternative to Proportional Hazards
It is standard practice for covariates to enter a parametric model through a single distributional parameter of interest, for example, the scale parameter in many standard survival models. Indeed, the well-known proportional hazards model is of this kind. In this paper we discuss a more general approach whereby covaria...
1901.03277v1
2019-11-05
Numerical methods for antiferromagnetics
Compared with ferromagnetic counterparts, antiferromagnetic materials are considered as the future of spintronic applications since these materials are robust against the magnetic perturbation, produce no stray field, and display ultrafast dynamics. There are (at least) two sets of magnetic moments in antiferromagnets ...
1911.01717v1
2023-02-06
Landau theory for ferro-paramagnetic phase transition in finitely-strained viscoelastic magnets
The thermodynamic model of visco-elastic deformable magnetic materials at finite strains is formulated in a fully Eulerian way in rates. The Landau theory applies for ferro-to-para-magnetic phase transition, the gradient theory (leading exchange energy) for magnetization with general mechanically dependent coefficient,...
2302.02850v1
2000-10-12
Friction in a solid lubricant film
Molecular dynamics study of a thin (one to five layers) lubricant film between two substrates in moving contact are performed using Langevin equations with an external damping coefficient depending on distance and velocity of atoms relative the substrates, motivated by microscopic configurations. They show that the min...
0010185v1
1993-06-01
Transport Properties of Solitons
We calculate in this article the transport coefficients which characterize the dynamics of solitons in quantum field theory using the methods of dissipative quantum systems. We show how the damping and diffusion coefficients of soliton-like excitations can be calculated using the integral functional formalism. The mode...
9306007v1
2008-10-01
Estimating Speed and Damping in the Stochastic Wave Equation
A parameter estimation problem is considered for a one-dimensional stochastic wave equation driven by additive space-time Gaussian white noise. The estimator is of spectral type and utilizes a finite number of the spatial Fourier coefficients of the solution. The asymptotic properties of the estimator are studied as ...
0810.0046v1
2009-06-23
Parameter Estimation in Diagonalizable Stochastic Hyperbolic Equations
A parameter estimation problem is considered for a linear stochastic hyperbolic equation driven by additive space-time Gaussian white noise. The damping/amplification operator is allowed to be unbounded. The estimator is of spectral type and utilizes a finite number of the spatial Fourier coefficients of the solution...
0906.4353v1
2011-12-11
Shear viscosity and spin diffusion coefficient of a two-dimensional Fermi gas
Using kinetic theory, we calculate the shear viscosity and the spin diffusion coefficient as well as the associated relaxation times for a two-component Fermi gas in two dimensions, as a function of temperature, coupling strength, polarization, and mass ratio of the two components. It is demonstrated that the minimum v...
1112.2395v2
2014-03-12
Logarithmic stability in determining two coefficients in a dissipative wave equation. Extensions to clamped Euler-Bernoulli beam and heat equations
We are concerned with the inverse problem of determining both the potential and the damping coefficient in a dissipative wave equation from boundary measurements. We establish stability estimates of logarithmic type when the measurements are given by the operator who maps the initial condition to Neumann boundary trace...
1403.3018v2
2015-03-16
Determining a boundary coefficient in a dissipative wave equation: Uniqueness and directional lipschitz stability
We are concerned with the problem of determining the damping boundary coefficient appearing in a dissipative wave equation from a single boundary measurement. We prove that the uniqueness holds at the origin provided that the initial condition is appropriately chosen. We show that the choice of the initial condition le...
1503.04528v1
2015-04-28
Fractional relaxation and fractional oscillation models involving Erdelyi-Kober integrals
We consider fractional relaxation and fractional oscillation equations involving Erdelyi-Kober integrals. In terms of Riemann-Liouville integrals, the equations we analyze can be understood as equations with time-varying coefficients. Replacing Riemann-Liouville integrals with Erdelyi-Kober-type integrals in certain fr...
1504.07568v1
2017-12-28
On well-posedness of Ericksen-Leslie's parabolic-hyperbolic liquid crystal model in compressible flow
We study the Ericksen-Leslie's parabolic-hyperbolic liquid crystal model in compressible flow. Inspired by our study for incompressible case \cite{Jiang-Luo-arXiv-2017} and some techniques from compressible Navier-Stokes equations, we prove the local-in-time existence of the classical solution to the system with finite...
1712.09799v1
2018-02-02
Energy decay and global solutions for a damped free boundary fluid-elastic structure interface model with variable coefficients in elasticity
We cope with a free boundary fluid-structure interaction model. In the model, the viscous incompressible fluid interacts with elastic body via the common boundary. The motion of the fluid is governed by Navier-Stokes equations while the displacement of elastic structure is described by variable coefficient wave equatio...
1802.00585v2
2020-05-23
Stability analysis of multi-term fractional-differential equations with three fractional derivatives
Necessary and sufficient stability and instability conditions are obtained for multi-term homogeneous linear fractional differential equations with three Caputo derivatives and constant coefficients. In both cases, fractional-order-dependent as well as fractional-order-independent characterisations of stability and ins...
2005.11486v1