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2020-02-27
Ultrafast magnetization dynamics in half-metallic Co$_2$FeAl Heusler alloy
We report on optically induced, ultrafast magnetization dynamics in the Heusler alloy $\mathrm{Co_{2}FeAl}$, probed by time-resolved magneto-optical Kerr effect. Experimental results are compared to results from electronic structure theory and atomistic spin-dynamics simulations. Experimentally, we find that the demagn...
2002.12255v1
2020-06-05
Controlling the nonlinear relaxation of quantized propagating magnons in nanodevices
Relaxation of linear magnetization dynamics is well described by the viscous Gilbert damping processes. However, for strong excitations, nonlinear damping processes such as the decay via magnon-magnon interactions emerge and trigger additional relaxation channels. Here, we use space- and time-resolved microfocused Bril...
2006.03400v2
2021-05-16
Anatomy of inertial magnons in ferromagnets
We analyze dispersion relations of magnons in ferromagnetic nanostructures with uniaxial anisotropy taking into account inertial terms, i.e. magnetic nutation. Inertial effects are parametrized by damping-independent parameter $\beta$, which allows for an unambiguous discrimination of inertial effects from Gilbert damp...
2105.07376v1
2021-11-16
Ultrathin ferrimagnetic GdFeCo films with very low damping
Ferromagnetic materials dominate as the magnetically active element in spintronic devices, but come with drawbacks such as large stray fields, and low operational frequencies. Compensated ferrimagnets provide an alternative as they combine the ultrafast magnetization dynamics of antiferromagnets with a ferromagnet-like...
2111.08768v1
2021-11-30
First and second order magnetic anisotropy and damping of europium iron garnet under high strain
Understanding and tailoring static and dynamic properties of magnetic insulator thin films is important for spintronic device applications. Here, we grow atomically flat epitaxial europium iron garnet (EuIG) thin films by pulsed laser deposition on (111)-oriented garnet substrates with a range of lattice parameters. By...
2111.15142v1
2022-10-01
Nonlinear features of the superconductor--ferromagnet--superconductor $\varphi_0$ Josephson junction in ferromagnetic resonance region
We demonstrate the manifestations of the nonlinear features in magnetic dynamics and IV-characteristics of the $\varphi_0$ Josephson junction in the ferromagnetic resonance region. We show that at small values of system parameters, namely, damping, spin-orbit interaction, and Josephson to magnetic energy ratio, the mag...
2210.00366v1
2023-12-16
Spin-torque nano-oscillator based on two in-plane magnetized synthetic ferrimagnets
We report the dynamic characterization of the spin-torque-driven in-plane precession modes of a spin-torque nano-oscillator based on two different synthetic ferrimagnets: a pinned one characterized by a strong RKKY interaction which is exchange coupled to an antiferromagnetic layer; and a second one, non-pinned charact...
2312.10451v2
2020-10-02
Multilevel quasi-Monte Carlo for random elliptic eigenvalue problems I: Regularity and error analysis
Stochastic PDE eigenvalue problems are useful models for quantifying the uncertainty in several applications from the physical sciences and engineering, e.g., structural vibration analysis, the criticality of a nuclear reactor or photonic crystal structures. In this paper we present a multilevel quasi-Monte Carlo (MLQM...
2010.01044v4
2021-03-05
Multilevel quasi-Monte Carlo for random elliptic eigenvalue problems II: Efficient algorithms and numerical results
Stochastic PDE eigenvalue problems often arise in the field of uncertainty quantification, whereby one seeks to quantify the uncertainty in an eigenvalue, or its eigenfunction. In this paper we present an efficient multilevel quasi-Monte Carlo (MLQMC) algorithm for computing the expectation of the smallest eigenvalue o...
2103.03407v3
2014-08-15
Linear hyperbolic equations with time-dependent propagation speed and strong damping
We consider a second order linear equation with a time-dependent coefficient c(t) in front of the "elastic" operator. For these equations it is well-known that a higher space-regularity of initial data compensates a lower time-regularity of c(t). In this paper we investigate the influence of a strong dissipation, nam...
1408.3499v1
2019-10-24
Topological damping Rashba spin orbit torque in ballistic magnetic domain walls
Rashba spin orbit torque derived from the broken inversion symmetry at ferromagnet/heavy metal interfaces has potential application in spintronic devices. In conventional description of the precessional and damping components of the Rashba spin orbit torque in magnetization textures, the decomposition coefficients are ...
1910.10977v2
2023-10-14
Exploring Damping Effect of Inner Control Loops for Grid-Forming VSCs
This paper presents an analytical approach to explore the damping effect of inner loops on grid-forming converters. First, an impedance model is proposed to characterize the behaviors of inner loops, thereby illustrating their influence on output impedance shaping. Then, based on the impedance representation, the compl...
2310.09660v1
2003-01-30
Dynamic effects of electromagnetic wave on a damped two-level atom
We studied the dynamic effects of an electromagnetic(EM) wave with circular polarization on a two-level damped atom. The results demonstrate interesting ac Stark split of energy levels of damped atom. The split levels have different energies and lifetimes, both of which depend on the interaction and the damping rate of...
0301166v1
2014-03-13
The best decay rate of the damped plate equation in a square
In this paper we study the best decay rate of the solutions of a damped plate equation in a square and with a homogeneous Dirichlet boundary conditions. We show that the fastest decay rate is given by the supremum of the real part of the spectrum of the infinitesimal generator of the underlying semigroup, if the dampin...
1403.3199v1
2015-02-16
Role of nonlinear anisotropic damping in the magnetization dynamics of topological solitons
The consequences of nonlinear anisotropic damping, driven by the presence of Rashba spin-orbit coupling in thin ferromagnetic metals, are examined for the dynamics of topological magnetic solitons such as domain walls, vortices, and skyrmions. The damping is found to affect Bloch and N\'eel walls differently in the ste...
1502.04695v2
2016-05-29
Damped Infinite Energy Solutions of the 3D Euler and Boussinesq Equations
We revisit a family of infinite-energy solutions of the 3D incompressible Euler equations proposed by Gibbon et al. [9] and shown to blowup in finite time by Constantin [6]. By adding a damping term to the momentum equation we examine how the damping coefficient can arrest this blowup. Further, we show that similar inf...
1605.08965v3
2016-06-14
Anomalous Damping of a Micro-electro-mechanical Oscillator in Superfluid $^3$He-B
The mechanical resonance properties of a micro-electro-mechanical oscillator with a gap of 1.25 $\mu$m was studied in superfluid $^3$He-B at various pressures. The oscillator was driven in the linear damping regime where the damping coefficient is independent of the oscillator velocity. The quality factor of the oscill...
1606.04483v2
2019-09-21
Stability for coupled waves with locally disturbed Kelvin-Voigt damping
We consider a coupled wave system with partial Kelvin-Voigt damping in the interval (-1,1), where one wave is dissipative and the other does not. When the damping is effective in the whole domain (-1,1) it was proven in H.Portillo Oquendo and P.Sanez Pacheco, optimal decay for coupled waves with Kelvin-voigt damping, A...
1909.09838v1
2020-06-30
Polynomial stabilization of non-smooth direct/indirect elastic/viscoelastic damping problem involving Bresse system
We consider an elastic/viscoelastic transmission problem for the Bresse system with fully Dirichlet or Dirichlet-Neumann-Neumann boundary conditions. The physical model consists of three wave equations coupled in certain pattern. The system is damped directly or indirectly by global or local Kelvin-Voigt damping. Actua...
2006.16595v2
2021-12-13
Cosmic ray streaming in the turbulent interstellar medium
We study the streaming instability of GeV$-100~$GeV cosmic rays (CRs) and its damping in the turbulent interstellar medium (ISM). We find that the damping of streaming instability is dominated by ion-neutral collisional damping in weakly ionized molecular clouds, turbulent damping in the highly ionized warm medium, and...
2112.06941v2
2023-12-07
Probing levitodynamics with multi-stochastic forces and the simple applications on the dark matter detection in optical levitation experiment
If the terrestrial environment is permeated by dark matter, the levitation experiences damping forces and fluctuations attributed to dark matter. This paper investigates levitodynamics with multiple stochastic forces, including thermal drag, photon recoil, feedback, etc., assuming that all of these forces adhere to the...
2312.04202v2
2013-08-17
Thickness and power dependence of the spin-pumping effect in Y3Fe5O12/Pt heterostructures measured by the inverse spin Hall effect
The dependence of the spin-pumping effect on the yttrium iron garnet (Y3Fe5O12, YIG) thickness detected by the inverse spin Hall effect (ISHE) has been investigated quantitatively. Due to the spin-pumping effect driven by the magnetization precession in the ferrimagnetic insulator YIG film a spin-polarized electron cur...
1308.3787v1
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
2020-09-29
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
2023-12-31
Molecular Hybridization Induced Antidamping and Sizable Enhanced Spin-to-Charge Conversion in Co20Fe60B20/$β$-W/C60 Heterostructures
Development of power efficient spintronics devices has been the compelling need in the post-CMOS technology era. The effective tunability of spin-orbit-coupling (SOC) in bulk and at the interfaces of hybrid materials stacking is a prerequisite for scaling down the dimension and power consumption of these devices. In th...
2401.00486v1
2011-01-28
Entanglement between two atoms in a damping Jaynes-Cummings model
The entanglement between two atoms in a damping Jaynes-Cummings model is investigated with different decay coefficients of the atoms from the upper level to other levels under detuning between the atomic frequency and the quantized light field frequency. The results indicate that the larger the decay coefficient is, th...
1101.5522v1
2015-05-27
Logarithmic stability in determining a boundary coefficient in an ibvp for the wave equation
In [2] we introduced a method combining together an observability inequality and a spectral decomposition to get a logarithmic stability estimate for the inverse problem of determining both the potential and the damping coefficient in a dissipative wave equation from boundary measurements. The present work deals with a...
1505.07248v1
2021-05-20
On the the critical exponent for the semilinear Euler-Poisson-Darboux-Tricomi equation with power nonlinearity
In this note, we derive a blow-up result for a semilinear generalized Tricomi equation with damping and mass terms having time-dependent coefficients. We consider these coefficients with critical decay rates. Due to this threshold nature of the time-dependent coefficients (both for the damping and for the mass), the mu...
2105.09879v2
2021-07-11
Space-time arithmetic quasi-periodic homogenization for damped wave equations
This paper is concerned with space-time homogenization problems for damped wave equations with spatially periodic oscillating elliptic coefficients and temporally (arithmetic) quasi-periodic oscillating viscosity coefficients. Main results consist of a homogenization theorem, qualitative properties of homogenized matri...
2107.04966v1
2014-08-26
Stability of an abstract-wave equation with delay and a Kelvin-Voigt damping
In this paper we consider a stabilization problem for the abstract-wave equation with delay. We prove an exponential stability result for appropriate damping coefficient. The proof of the main result is based on a frequency-domain approach.
1408.6261v2
2015-10-14
The General Solution to Vlasov Equation and Linear Landau Damping
A general solution to linearized Vlasov equation for an electron electrostatic wave in a homogeneous unmagnetized plasma is derived. The quasi-linear diffusion coefficient resulting from this solution is a continuous function of omega in contrast to that derived from the traditional Vlasov treatment. The general soluti...
1510.03949v1
2017-08-24
Nonlinear network dynamics for interconnected micro-grids
This paper deals with transient stability in interconnected micro-grids. The main contribution involves i) robust classification of transient dynamics for different intervals of the micro-grid parameters (synchronization, inertia, and damping); ii) exploration of the analogies with consensus dynamics and bounds on the ...
1708.07296v1
2020-09-16
Exponential decay for semilinear wave equations with viscoelastic damping and delay feedback
In this paper we study a class of semilinear wave type equations with viscoelastic damping and delay feedback with time variable coefficient. By combining semigroup arguments, careful energy estimates and an iterative approach we are able to prove, under suitable assumptions, a well-posedness result and an exponential ...
2009.07777v1
2022-12-04
Inverse problem of recovering the time-dependent damping and nonlinear terms for wave equations
In this paper, we consider the inverse boundary problems of recovering the time-dependent nonlinearity and damping term for a semilinear wave equation on a Riemannian manifold. The Carleman estimate and the construction of Gaussian beams together with the higher order linearization are respectively used to derive the u...
2212.01815v2
2022-10-08
Recover all Coefficients in Second-Order Hyperbolic Equations from Finite Sets of Boundary Measurements
We consider the inverse hyperbolic problem of recovering all spatial dependent coefficients, which are the wave speed, the damping coefficient, potential coefficient and gradient coefficient, in a second-order hyperbolic equation defined on an open bounded domain with smooth enough boundary. We show that by appropriate...
2210.03865v1
2002-04-25
Statics and Fast Dynamics of Nanomagnets with Vortex Structure
Within the framework of the Landau-Lifshitz-Gilbert equation, using permalloy parameters, we study the statics and dynamics of flat circular magnetic nano-structures with an in-plane magnetic vortex configuration, putting particular emphasis on the (planar) vorticity of the magnetic state and on the (perpendicular) pol...
0204541v3
2007-03-15
Functional Keldysh Theory of Spin Torques
We present a microscopic treatment of current-induced torques and thermal fluctuations in itinerant ferromagnets based on a functional formulation of the Keldysh formalism. We find that the nonequilibrium magnetization dynamics is governed by a stochastic Landau-Lifschitz-Gilbert equation with spin transfer torques. We...
0703414v2
2010-10-04
Thermal fluctuation field for current-induced domain wall motion
Current-induced domain wall motion in magnetic nanowires is affected by thermal fluctuation. In order to account for this effect, the Landau-Lifshitz-Gilbert equation includes a thermal fluctuation field and literature often utilizes the fluctuation-dissipation theorem to characterize statistical properties of the ther...
1010.0478v2
2015-06-03
Antidamping spin-orbit torque driven by spin-flip reflection mechanism on the surface of a topological insulator: A time-dependent nonequilibrium Green function approach
Motivated by recent experiments observing spin-orbit torque (SOT) acting on the magnetization $\vec{m}$ of a ferromagnetic (F) overlayer on the surface of a three-dimensional topological insulator (TI), we investigate the origin of the SOT and the magnetization dynamics in such systems. We predict that lateral F/TI bil...
1506.01303v3
2015-07-11
Realization of the thermal equilibrium in inhomogeneous magnetic systems by the Landau-Lifshitz-Gilbert equation with stochastic noise, and its dynamical aspects
It is crucially important to investigate effects of temperature on magnetic properties such as critical phenomena, nucleation, pinning, domain wall motion, coercivity, etc. The Landau-Lifshitz-Gilbert (LLG) equation has been applied extensively to study dynamics of magnetic properties. Approaches of Langevin noises hav...
1507.03075v1
2017-01-12
Dynamic coupling of ferromagnets via spin Hall magnetoresistance
The synchronized magnetization dynamics in ferromagnets on a nonmagnetic heavy metal caused by the spin Hall effect is investigated theoretically. The direct and inverse spin Hall effects near the ferromagnetic/nonmagnetic interface generate longitudinal and transverse electric currents. The phenomenon is known as the ...
1701.03201v2
2018-10-16
Superfluid spin transport in ferro- and antiferromagnets
This paper focuses on spin superfluid transport, observation of which was recently reported in antiferromagnet Cr$_2$O$_3$ [Yuan et al., Sci. Adv. 4, eaat1098 (2018)]. This paper analyzes the role of dissipation in transformation of spin current injected with incoherent magnons to a superfluid spin current near the int...
1810.07020v4
2020-02-20
Stoner-Wohlfarth switching of the condensate magnetization in a dipolar spinor gas and the metrology of excitation damping
We consider quasi-one-dimensional dipolar spinor Bose-Einstein condensates in the homogeneous-local-spin-orientation approximation, that is with unidirectional local magnetization. By analytically calculating the exact effective dipole-dipole interaction, we derive a Landau-Lifshitz-Gilbert equation for the dissipative...
2002.08723v2
2022-06-20
First-principles calculation of the parameters used by atomistic magnetic simulations
While the ground state of magnetic materials is in general well described on the basis of spin density functional theory (SDFT), the theoretical description of finite-temperature and non-equilibrium properties require an extension beyond the standard SDFT. Time-dependent SDFT (TD-SDFT), which give for example access to...
2206.09969v1
2023-09-25
Ultrafast Demagnetization through Femtosecond Generation of Non-thermal Magnons
Ultrafast laser excitation of ferromagnetic metals gives rise to correlated, highly non-equilibrium dynamics of electrons, spins and lattice, which are, however, poorly described by the widely-used three-temperature model (3TM). Here, we develop a fully ab-initio parameterized out-of-equilibrium theory based on a quant...
2309.14167v3
2023-12-12
Sliding Dynamics of Current-Driven Skyrmion Crystal and Helix in Chiral Magnets
The skyrmion crystal (SkX) and helix (HL) phases, present in typical chiral magnets, can each be considered as forms of density waves but with distinct topologies. The SkX exhibits gyrodynamics analogous to electrons under a magnetic field, while the HL state resembles topological trivial spin density waves. However, u...
2312.07116v2
2007-01-08
Coefficient of restitution for viscoelastic disks
The dissipative collision of two identical viscoelastic disks is studied. By using a known law for the elastic part of the interaction force and the viscoelastic damping model an analytical solution for the coefficient of restitution shall be given. The coefficient of restitution depends significantly on the impact vel...
0701142v1
2008-02-29
Heat conduction and Fourier's law in a class of many particle dispersing billiards
We consider the motion of many confined billiard balls in interaction and discuss their transport and chaotic properties. In spite of the absence of mass transport, due to confinement, energy transport can take place through binary collisions between neighbouring particles. We explore the conditions under which relaxat...
0802.4455v3
2014-07-01
Transport properties of Lévy walks: an analysis in terms of multistate processes
Continuous time random walks combining diffusive and ballistic regimes are introduced to describe a class of L\'evy walks on lattices. By including exponentially-distributed waiting times separating the successive jump events of a walker, we are led to a description of such L\'evy walks in terms of multistate processes...
1407.0227v2
2015-01-21
Lévy walks on lattices as multi-state processes
Continuous-time random walks combining diffusive scattering and ballistic propagation on lattices model a class of L\'evy walks. The assumption that transitions in the scattering phase occur with exponentially-distributed waiting times leads to a description of the process in terms of multiple states, whose distributio...
1501.05216v1
2015-01-31
Bases and Structure Constants of Generalized Splines with Integer Coefficients on Cycles
An integer generalized spline is a set of vertex labels on an edge-labeled graph that satisfy the condition that if two vertices are joined by an edge, the vertex labels are congruent modulo the edge label. Foundational work on these objects comes from Gilbert, Polster, and Tymoczko, who generalize ideas from geometry/...
1502.00176v1
2019-05-31
Characterizing the mod-$\ell$ local Langlands correspondence by nilpotent gamma factors
Let $F$ be a $p$-adic field and choose $k$ an algebraic closure of $\mathbb{F}_{\ell}$, with $\ell$ different from $p$. We define ``nilpotent lifts'' of irreducible generic $k$-representations of $GL_n(F)$, which take coefficients in Artin local $k$-algebras. We show that an irreducible generic $\ell$-modular represent...
1905.13487v2
2020-01-31
An efficient automated data analytics approach to large scale computational comparative linguistics
This research project aimed to overcome the challenge of analysing human language relationships, facilitate the grouping of languages and formation of genealogical relationship between them by developing automated comparison techniques. Techniques were based on the phonetic representation of certain key words and conce...
2001.11899v1
2022-06-22
Homogenization of the Landau-Lifshitz-Gilbert equation with natural boundary condition
The full Landau-Lifshitz-Gilbert equation with periodic material coefficients and natural boundary condition is employed to model the magnetization dynamics in composite ferromagnets. In this work, we establish the convergence between the homogenized solution and the original solution via a Lax equivalence theorem kind...
2206.10948v1
2023-10-13
Unified framework of the microscopic Landau-Lifshitz-Gilbert equation and its application to Skyrmion dynamics
The Landau-Lifshitz-Gilbert (LLG) equation is widely used to describe magnetization dynamics. We develop a unified framework of the microscopic LLG equation based on the nonequilibrium Green's function formalism. We present a unified treatment for expressing the microscopic LLG equation in several limiting cases, inclu...
2310.08807v1
2004-04-19
Nonlinear response of superparamagnets with finite damping: an analytical approach
The strongly damping-dependent nonlinear dynamical response of classical superparamagnets is investigated by means of an analytical approach. Using rigorous balance equations for the spin occupation numbers a simple approximate expression is derived for the nonlinear susceptibility. The results are in good agreement wi...
0404445v1
2005-05-10
Highly Damped Quasinormal Modes of Generic Single Horizon Black Holes
We calculate analytically the highly damped quasinormal mode spectra of generic single-horizon black holes using the rigorous WKB techniques of Andersson and Howls\cite{Andersson}. We thereby provide a firm foundation for previous analysis, and point out some of their possible limitations. The numerical coefficient in ...
0505044v1
2003-09-15
Eigenfrequencies and expansions for damped wave equations
We study eigenfrequencies and propagator expansions for damped wave equations on compact manifolds. Under the assumption of geometric control, the propagator is shown to admit an expansion in terms of finitely many eigenmodes near the real axis, with an error term exponentially decaying in time. In the presence of a no...
0309250v1
2010-03-08
A single-ion nonlinear mechanical oscillator
We study the steady state motion of a single trapped ion oscillator driven to the nonlinear regime. Damping is achieved via Doppler laser-cooling. The ion motion is found to be well described by the Duffing oscillator model with an additional nonlinear damping term. We demonstrate a unique ability of tuning both the li...
1003.1577v1
2012-02-24
Small data global existence for the semilinear wave equation with space-time dependent damping
In this paper we consider the critical exponent problem for the semilinear wave equation with space-time dependent damping. When the damping is effective, it is expected that the critical exponent agrees with that of only space dependent coefficient case. We shall prove that there exists a unique global solution for sm...
1202.5379v1
2012-03-21
Approximate rogue wave solutions of the forced and damped Nonlinear Schrödinger equation for water waves
We consider the effect of the wind and the dissipation on the nonlinear stages of the modulational instability. By applying a suitable transformation, we map the forced/damped Nonlinear Schr\"odinger (NLS) equation into the standard NLS with constant coefficients. The transformation is valid as long as |{\Gamma}t| \ll ...
1203.4735v1
2013-11-16
Shear viscosity due to the Landau damping from quark-pion interaction
We have calculated the shear viscosity coefficient $\eta$ of the strongly interacting matter in the relaxation time approximation, where a quasi particle description of quarks with its dynamical mass is considered from NJL model. Due to the thermodynamic scattering of quarks with pseudo scalar type condensate (i.e. pio...
1311.4070v1
2014-03-24
Existence Results for Some Damped Second-Order Volterra Integro-Differential Equations
In this paper we make a subtle use of operator theory techniques and the well-known Schauder fixed-point principle to establish the existence of pseudo-almost automorphic solutions to some second-order damped integro-differential equations with pseudo-almost automorphic coefficients. In order to illustrate our main res...
1403.5955v1
2014-08-09
Local existence results for the Westervelt equation with nonlinear damping and Neumann as well as absorbing boundary conditions
We investigate the Westervelt equation with several versions of nonlinear damping and lower order damping terms and Neumann as well as absorbing boundary conditions. We prove local in time existence of weak solutions under the assumption that the initial and boundary data are sufficiently small. Additionally, we prove ...
1408.2160v1
2015-03-03
Large Deviations for the Langevin equation with strong damping
We study large deviations in the Langevin dynamics, with damping of order $\e^{-1}$ and noise of order $1$, as $\e\downarrow 0$. The damping coefficient is assumed to be state dependent. We proceed first with a change of time and then, we use a weak convergence approach to large deviations and their equivalent formulat...
1503.01027v1
2017-06-15
Fractional Driven Damped Oscillator
The resonances associated with a fractional damped oscillator which is driven by an oscillatory external force are studied. It is shown that such resonances can be manipulated by tuning up either the coefficient of the fractional damping or the order of the corresponding fractional derivatives.
1706.08596v1
2017-09-13
Life-span of blowup solutions to semilinear wave equation with space-dependent critical damping
This paper is concerned with the blowup phenomena for initial value problem of semilinear wave equation with critical space-dependent damping term (DW:$V$). The main result of the present paper is to give a solution of the problem and to provide a sharp estimate for lifespan for such a solution when $\frac{N}{N-1}<p\le...
1709.04401v1
2018-06-08
Brownian motion of magnetic domain walls and skyrmions, and their diffusion constants
Extended numerical simulations enable to ascertain the diffusive behavior at finite temperatures of chiral walls and skyrmions in ultra-thin model Co layers exhibiting symmetric - Heisenberg - as well as antisymmetric - Dzyaloshinskii-Moriya - exchange interactions. The Brownian motion of walls and skyrmions is shown t...
1806.03172v1
2020-02-09
Fujita modified exponent for scale invariant damped semilinear wave equations
The aim of this paper is to prove a blow up result of the solution for a semilinear scale invariant damped wave equation under a suitable decay condition on radial initial data. The admissible range for the power of the nonlinear term depends both on the damping coefficient and on the pointwise decay order of the initi...
2002.03418v2
2020-05-24
A transmission problem for the Timoshenko system with one local Kelvin-Voigt damping and non-smooth coefficient at the interface
In this paper, we study the indirect stability of Timoshenko system with local or global Kelvin-Voigt damping, under fully Dirichlet or mixed boundary conditions. Unlike the results of H. L. Zhao, K. S. Liu, and C. G. Zhang and of X. Tian and Q. Zhang, in this paper, we consider the Timoshenko system with only one loca...
2005.12756v1
2020-08-11
An inverse spectral problem for a damped wave operator
This paper proposes a new and efficient numerical algorithm for recovering the damping coefficient from the spectrum of a damped wave operator, which is a classical Borg-Levinson inverse spectral problem. The algorithm is based on inverting a sequence of trace formulas, which are deduced by a recursive formula, bridgin...
2008.04523v1
2020-08-18
A class of Finite difference Methods for solving inhomogeneous damped wave equations
In this paper, a class of finite difference numerical techniques is presented to solve the second-order linear inhomogeneous damped wave equation. The consistency, stability, and convergences of these numerical schemes are discussed. The results obtained are compared to the exact solution, ordinary explicit, implicit f...
2008.08043v2
2020-09-10
Blow-up results for semilinear damped wave equations in Einstein-de Sitter spacetime
We prove by using an iteration argument some blow-up results for a semilinear damped wave equation in generalized Einstein-de Sitter spacetime with a time-dependent coefficient for the damping term and power nonlinearity. Then, we conjecture an expression for the critical exponent due to the main blow-up results, which...
2009.05372v1
2021-06-16
Sharp upper and lower bounds of the attractor dimension for 3D damped Euler-Bardina equations
The dependence of the fractal dimension of global attractors for the damped 3D Euler--Bardina equations on the regularization parameter $\alpha>0$ and Ekman damping coefficient $\gamma>0$ is studied. We present explicit upper bounds for this dimension for the case of the whole space, periodic boundary conditions, and t...
2106.09077v1
2022-03-12
Stability for nonlinear wave motions damped by time-dependent frictions
We are concerned with the dynamical behavior of solutions to semilinear wave systems with time-varying damping and nonconvex force potential. Our result shows that the dynamical behavior of solution is asymptotically stable without any bifurcation and chaos. And it is a sharp condition on the damping coefficient for th...
2203.06312v1
2022-06-07
Decay property of solutions to the wave equation with space-dependent damping, absorbing nonlinearity, and polynomially decaying data
We study the large time behavior of solutions to the semilinear wave equation with space-dependent damping and absorbing nonlinearity in the whole space or exterior domains. Our result shows how the amplitude of the damping coefficient, the power of the nonlinearity, and the decay rate of the initial data at the spatia...
2206.03218v2
2022-12-18
Exponential decay of solutions of damped wave equations in one dimensional space in the $L^p$ framework for various boundary conditions
We establish the decay of the solutions of the damped wave equations in one dimensional space for the Dirichlet, Neumann, and dynamic boundary conditions where the damping coefficient is a function of space and time. The analysis is based on the study of the corresponding hyperbolic systems associated with the Riemann ...
2212.09164v1
2023-05-03
Lyapunov functions for linear damped wave equations in one-dimensional space with dynamic boundary conditions
We establish the exponential decay of the solutions of the damped wave equations in one-dimensional space where the damping coefficient is a nowhere-vanishing function of space. The considered PDE is associated with several dynamic boundary conditions, also referred to as Wentzell/Ventzel boundary conditions in the lit...
2305.01969v2
2023-07-12
Asymptotic behavior of solutions to the Cauchy problem for 1-D p-system with space dependent damping
We consider the Cauchy problem for one-dimensional p-system with damping of space-dependent coefficient. This system models the compressible flow through porous media in the Lagrangean coordinate. Our concern is an asymptotic behavior of solutions, which is expected to be the diffusion wave based on the Darcy law. To s...
2307.05865v1
2023-07-12
Parabolic-elliptic Keller-Segel's system
We study on the whole space R d the compressible Euler system with damping coupled to the Poisson equation when the damping coefficient tends towards infinity. We first prove a result of global existence for the Euler-Poisson system in the case where the damping is large enough, then, in a second step, we rigorously ju...
2307.05981v1
2021-07-29
Microscopic analysis of sound attenuation in low-temperature amorphous solids reveals quantitative importance of non-affine effects
Sound attenuation in low temperature amorphous solids originates from their disordered structure. However, its detailed mechanism is still being debated. Here we analyze sound attenuation starting directly from the microscopic equations of motion. We derive an exact expression for the zero-temperature sound damping coe...
2107.14254v2
2023-10-29
Asymptotic profiles for the Cauchy problem of damped beam equation with two variable coefficients and derivative nonlinearity
In this article we investigate the asymptotic profile of solutions for the Cauchy problem of the nonlinear damped beam equation with two variable coefficients: \[ \partial_t^2 u + b(t) \partial_t u - a(t) \partial_x^2 u + \partial_x^4 u = \partial_x \left( N(\partial_x u) \right). \] In the authors' previous article ...
2310.18878v1
2023-08-14
Temperature Evolution of Magnon Propagation Length in Tm$_3$Fe$_5$O$_{12}$ Thin Films: Roles of Magnetic Anisotropy and Gilbert Damping
The magnon propagation length ($\langle\xi\rangle$) of a ferro/ferrimagnet (FM) is one of the key factors that controls the generation and propagation of thermally-driven spin current in FM/heavy metal (HM) bilayer based spincaloritronic devices. Theory predicts that for the FM layer, $\langle\xi\rangle$ is inversely p...
2308.07236v3
2015-06-23
The remarkable effectiveness of time-dependent damping terms for second order evolution equations
We consider a second order linear evolution equation with a dissipative term multiplied by a time-dependent coefficient. Our aim is to design the coefficient in such a way that all solutions decay in time as fast as possible. We discover that constant coefficients do not achieve the goal, as well as time-dependent co...
1506.06915v1
2018-04-20
A Weakly Nonlinear Model for the Damping of Resonantly Forced Density Waves in Dense Planetary Rings
In this paper we address the stability of resonantly forced density waves in dense planetary rings. Already by Goldreich & Tremaine (1978) it has been argued that density waves might be unstable, depending on the relationship between the ring's viscosity and the surface mass density. In the recent paper Schmidt et ...
1804.07674v1
2006-02-17
Damped quantum harmonic oscillator
In the framework of the Lindblad theory for open quantum systems the damping of the harmonic oscillator is studied. A generalization of the fundamental constraints on quantum mechanical diffusion coefficients which appear in the master equation for the damped quantum oscillator is presented; the Schr\"odinger and Heise...
0602149v1
2006-05-25
Time Quantified Monte Carlo Algorithm for Interacting Spin Array Micromagnetic Dynamics
In this paper, we reexamine the validity of using time quantified Monte Carlo (TQMC) method [Phys. Rev. Lett. 84, 163 (2000); Phys. Rev. Lett. 96, 067208 (2006)] in simulating the stochastic dynamics of interacting magnetic nanoparticles. The Fokker-Planck coefficients corresponding to both TQMC and Langevin dynamical ...
0605621v1
2000-07-10
Fractal Dimensions of the Hydrodynamic Modes of Diffusion
We consider the time-dependent statistical distributions of diffusive processes in relaxation to a stationary state for simple, two dimensional chaotic models based upon random walks on a line. We show that the cumulative functions of the hydrodynamic modes of diffusion form fractal curves in the complex plane, with a ...
0007008v1
2000-10-06
The Fractality of the Hydrodynamic Modes of Diffusion
Transport by normal diffusion can be decomposed into the so-called hydrodynamic modes which relax exponentially toward the equilibrium state. In chaotic systems with two degrees of freedom, the fine scale structure of these hydrodynamic modes is singular and fractal. We characterize them by their Hausdorff dimension wh...
0010017v1
1998-05-29
Atom cooling and trapping by disorder
We demonstrate the possibility of three-dimensional cooling of neutral atoms by illuminating them with two counterpropagating laser beams of mutually orthogonal linear polarization, where one of the lasers is a speckle field, i.e. a highly disordered but stationary coherent light field. This configuration gives rise to...
9805037v1
2014-08-11
An optimal irrigation network with infinitely many branching points
The Gilbert-Steiner problem is a mass transportation problem, where the cost of the transportation depends on the network used to move the mass and it is proportional to a certain power of the "flow". In this paper, we introduce a new formulation of the problem, which turns it into the minimization of a convex function...
1408.2406v1
2023-03-15
Algebraic Geometry codes in the sum-rank metric
We introduce the first geometric construction of codes in the sum-rank metric, which we called linearized Algebraic Geometry codes, using quotients of the ring of Ore polynomials with coefficients in the function field of an algebraic curve. We study the parameters of these codes and give lower bounds for their dimensi...
2303.08903v2
2023-05-31
Codes from Goppa codes
On a Goppa code whose structure polynomial has coefficients in the symbol field, the Frobenius acts. Its fixed codewords form a subcode. Deleting the naturally occurred redundance, we obtain a new code. It is proved that these new codes approach the Gilbert-Varshamov bound. It is also proved that these codes can be dec...
2305.19565v5
2023-07-21
Thermomechanics of ferri-antiferromagnetic phase transition in finitely-strained rocks towards paleomagnetism
The thermodynamic model of visco-elastic deformable magnetic materials at finite strains is formulated in a fully Eulerian way in rates with the aim to describe thermoremanent paleomagnetism in crustal rocks. The Landau theory applied to a ferro-to-para-magnetic phase transition, the gradient theory for magnetization (...
2307.11826v2
2011-06-23
Ratchet effect on a relativistic particle driven by external forces
We study the ratchet effect of a damped relativistic particle driven by both asymmetric temporal bi-harmonic and time-periodic piecewise constant forces. This system can be formally solved for any external force, providing the ratchet velocity as a non-linear functional of the driving force. This allows us to explicitl...
1106.4861v1
2011-07-17
Nonlinear-damping continuation of the nonlinear Schrödinger equation - a numerical study
We study the nonlinear-damping continuation of singular solutions of the critical and supercritical NLS. Our simulations suggest that for generic initial conditions that lead to collapse in the undamped NLS, the solution of the weakly-damped NLS $$ i\psi_t(t,\X)+\Delta\psi+|\psi|^{p-1}\psi+i\delta|\psi|^{q-1}\psi=0,\qq...
1107.3281v1
2018-04-06
Exponential Integrators Preserving Local Conservation Laws of PDEs with Time-Dependent Damping/Driving Forces
Structure-preserving algorithms for solving conservative PDEs with added linear dissipation are generalized to systems with time-dependent damping/driving terms. This study is motivated by several PDE models of physical phenomena, such as Korteweg-de Vries, Klein-Gordon, Schr\"{o}dinger, and Camassa-Holm equations, all...
1804.02266v1
2019-11-13
Dipole oscillations of fermionic superfluids along the BEC-BCS crossover in disordered potentials
We investigate dipole oscillations of ultracold Fermi gases along the BEC-BCS crossover through disordered potentials. We observe a disorder-induced damping of oscillations as well as a change of the fundamental Kohn-mode frequency. The measurement results are compared to numerical density matrix renormalization group ...
1911.05638v1
2020-05-16
Simultaneous observation of anti-damping and inverse spin Hall effect in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$/Pt bilayer system
Manganites have shown potential in spintronics because they exhibit high spin polarization. Here, by ferromagnetic resonance we have studied the damping properties of La$_{0.67}$Sr$_{0.33}$MnO$_{3}$/Pt bilayers which are prepared by oxide molecular beam epitaxy. The damping coefficient ($\alpha$) of La$_{0.67}$Sr$_{0.3...
2005.07848v3
2021-10-26
Theory of sound attenuation in amorphous solids from nonaffine motions
We present a theoretical derivation of acoustic phonon damping in amorphous solids based on the nonaffine response formalism for the viscoelasticity of amorphous solids. The analytical theory takes into account the nonaffine displacements in transverse waves and is able to predict both the ubiquitous low-energy diffusi...
2110.13446v2