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47
2000-08-03
Kinetic Friction due to Ohm's Law Heating
Using both a recent calculation by Bruch of the damping of the motion of a monolayer nitrogen film oscillating harmonically on a metallic surface due to Ohm's law heating and a Thomas-Fermi approximation treatment of the Ohm's law heating mechanism, which accounts for the nonzero thickness of the surface region of a me...
0008063v3
2001-11-07
Study of Magnetic Excitation in Singlet-Ground-State Magnets CsFeCl$_3$ and RbFeCl$_3$ by Nuclear Magnetic Relaxation
The temperature dependences of spin-lattice relaxation time $T_1$ of $^{133}$Cs in CsFeCl$_3$ and $^{87}$Rb in RbFeCl$_3$ were measured in the temperature range between 1.5 K and 22 K, at various fields up to 7 T applied parallel (or perpendicular) to the c-axis, and the analysis was made on the basis of the DCEFA. The...
0111097v2
2003-02-10
The differential sum rule for the relaxation rate in dirty superconductors
We consider the differential sum rule for the effective scattering rate $% 1/\tau (\omega)$ and optical conductivity $\sigma_{1}(\omega) $ in a dirty BCS superconductor, for arbitrary ratio of the superconducting gap $% \Delta$ and the normal state constant damping rate $1/\tau$. We show that if $\tau$ is independent o...
0302191v1
2003-02-12
Electronic-vibrational coupling in single-molecule devices
Experiments studying vibrational effects on electronic transport through single molecules have observed several seemingly inconsistent behaviors, ranging from up to 30 harmonics of a vibrational frequency in one experiment, to an absence of higher-harmonic peaks in another. We study the different manifestations of elec...
0302222v2
2003-04-09
Plastic Flow in Two-Dimensional Solids
A time-dependent Ginzburg-Landau model of plastic deformation in two-dimensional solids is presented. The fundamental dynamic variables are the displacement field $\bi u$ and the lattice velocity ${\bi v}=\p {\bi u}/\p t$. Damping is assumed to arise from the shear viscosity in the momentum equation. The elastic energy...
0304209v1
2004-02-16
Superconducting Qubits and the Physics of Josephson Junctions
We describe in this paper how the nonlinear Josephson inductance is the crucial circuit element for all Josephson qubits. We discuss the three types of qubit circuits, and show how these circuits use this nonlinearity in unique manners. We give a brief derivation of the BCS theory, highlighting the appearance of the ma...
0402415v1
2004-04-24
On the Modulational Instability of the Nonlinear Schrödinger Equation with Dissipation
The modulational instability of spatially uniform states in the nonlinear Schr\"odinger equation is examined in the presence of higher-order dissipation. The study is motivated by results on the effects of three-body recombination in Bose-Einstein condensates, as well as by the important recent work of Segur et al. on ...
0404597v1
2005-01-04
Local spectroscopy and atomic imaging of tunneling current, forces and dissipation on graphite
Theory predicts that the currents in scanning tunneling microscopy (STM) and the attractive forces measured in atomic force microscopy (AFM) are directly related. Atomic images obtained in an attractive AFM mode should therefore be redundant because they should be \emph{similar} to STM. Here, we show that while the dis...
0501045v1
2005-03-01
Discrete models of dislocations and their motion in cubic crystals
A discrete model describing defects in crystal lattices and having the standard linear anisotropic elasticity as its continuum limit is proposed. The main ingredients entering the model are the elastic stiffness constants of the material and a dimensionless periodic function that restores the translation invariance of ...
0503020v1
2005-05-24
Quasi-Elastic Scattering, Random Fields and phonon-coupling effects in PbMg1/3Nb2/3O3
The low-energy part of the vibration spectrum in PbMg$_{1/3}$Nb$_{2/3}$O$_3$ (PMN) relaxor ferroelectric has been studied by neutron scattering above and below the Burns temperature, T$_d$. The transverse acoustic and the lowest transverse optic phonons are strongly coupled and we have obtained a model for this couplin...
0505584v1
2005-07-20
All-optical probe of precessional magnetization dynamics in exchange biased NiFe/FeMn bilayers
An internal anisotropy pulse field is launched by an 8.3 ps short laser excitation, which triggers precessional magnetization dynamics of a polycrystalline NiFe/FeMn exchange bias system on the picosecond timescale. Due to the excitation the unidirectional anisotropy and, thus, the exchange coupling across the interfac...
0507475v1
2005-12-26
Spin waves in a band ferromagnet: spin-rotationally symmetric study with self-energy and vertex corrections
First-order quantum corrections to the transverse spin-fluctuation propagator are obtained within a systematic inverse-degeneracy 1/N expansion, which provides a spin-rotationally symmetric scheme for including self-energy and vertex corrections while preserving the Goldstone mode. An expression is obtained for the spi...
0512648v2
2006-02-18
Optical phonons in new ordered perovskite Sr2Cu(Re0.69Ca0.31) Oy system observed by infrared reflectance spectroscopy
We report infrared reflectivity spectra for a new correlated cupric oxide system Sr2Cu(Re0.69Ca0.31)Oy with y ~ 0.6 at several temperatures ranging between 8 and 380 K. The reflectivity spectrum at 300 K comprises of several optical phonons. A couple of residual bands located around 315 and 653 cm-1 exhibit exceptional...
0602438v1
2006-05-03
Non equilibrium inertial dynamics of colloidal systems
We consider the properties of a one dimensional fluid of brownian inertial hard-core particles, whose microscopic dynamics is partially damped by a heat-bath. Direct interactions among the particles are represented as binary, instantaneous elastic collisions. Collisions with the heath bath are accounted for by a Fokker...
0605094v1
2006-08-30
Current-Driven Domain-Wall Dynamics in Curved Ferromagnetic Nanowires
The current-induced motion of a domain wall in a semicircle nanowire with applied Zeeman field is investigated. Starting from a micromagnetic model we derive an analytical solution which characterizes the domain-wall motion as a harmonic oscillation. This solution relates the micromagnetic material parameters with the ...
0608680v1
2007-02-23
Electronic viscosity in a quantum well: A test for the local density approximation
In the local density approximation (LDA) for electronic time-dependent current-density functional theory (TDCDFT) many-body effects are described in terms of the visco-elastic constants of the homogeneous three-dimensional electron gas. In this paper we critically examine the applicability of the three-dimensional LDA ...
0702538v1
2007-02-28
Bond Stiffening in Nanoclusters and its Consequences
We have used density functional perturbation theory to investigate the stiffness of interatomic bonds in small clusters of Si, Sn and Pb. As the number of atoms in a cluster is decreased, there is a marked shortening and stiffening of bonds. The competing factors of fewer but stiffer bonds in clusters result in softer ...
0702677v1
2007-03-12
Velocity dependence of friction and Kramers relaxation rates
We study the influence of the velocity dependence of friction on the escape of a Brownian particle from the deep potential well ($E_{b} \gg k_{B}T$, $E_{b}$ is the barrier height, $k_{B}$ is the Boltzmann constant, $T$ is the bath temperature). The bath-induced relaxation is treated within the Rayleigh model (a heavy p...
0703312v1
1995-04-12
STABLE CLOCKS AND GENERAL RELATIVITY
We survey the role of stable clocks in general relativity. Clock comparisons have provided important tests of the Einstein Equivalence Principle, which underlies metric gravity. These include tests of the isotropy of clock comparisons (verification of local Lorentz invariance) and tests of the homogeneity of clock comp...
9504017v1
2000-11-18
Third post-Newtonian dynamics of compact binaries: Noetherian conserved quantities and equivalence between the harmonic-coordinate and ADM-Hamiltonian formalisms
A Lagrangian from which derive the third post-Newtonian (3PN) equations of motion of compact binaries (neglecting the radiation reaction damping) is obtained. The 3PN equations of motion were computed previously by Blanchet and Faye in harmonic coordinates. The Lagrangian depends on the harmonic-coordinate positions, v...
0011063v2
2006-10-06
New Insights into Uniformly Accelerated Detector in a Quantum Field
We obtained an exact solution for a uniformly accelerated Unruh-DeWitt detector interacting with a massless scalar field in (3+1) dimensions which enables us to study the entire evolution of the total system, from the initial transient to late-time steady state. We find that the Unruh effect as derived from time-depend...
0610024v1
1995-09-29
Thermal Fermionic Dispersion Relations in a Magnetic Field
The thermal self-energy of an electron in a static uniform magnetic field $B$ is calculated to first order in the fine structure constant $\alpha $ and to all orders in $eB$. We use two methods, one based on the Furry picture and another based on Schwinger's proper-time method. As external states we consider relativist...
9509418v1
1999-12-22
Chaotic inflation on the brane
We consider slow-roll inflation in the context of recently proposed four-dimensional effective gravity induced on the world-volume of a three-brane in five-dimensional Einstein gravity. We find significant modifications of the simplest chaotic inflationary scenario when the five-dimensional Planck scale is below about ...
9912464v3
2003-07-05
Hard Loops, Soft Loops, and High Density Effective Field Theory
We study several issues related to the use of effective field theories in QCD at large baryon density. We show that the power counting is complicated by the appearance of two scales inside loop integrals. Hard dense loops involve the large scale $\mu^2$ and lead to phenomena such as screening and damping at the scale $...
0307074v1
2004-04-21
Rho - Omega Splitting and Mixing in Nuclear Matter
We investigate the splitting and mixing of $\rho$ and $\omega$ mesons in nuclear matter. The calculations were performed on the basis of QCD sum rules and include all operators up to mass dimension-6 twist-4 and up to first order in the coupling constants. Special attention is devoted to the impact of the scalar 4-quar...
0404176v5
2007-02-13
Universality of QCD traveling-waves with running coupling
The Balitsky-Kovchegov QCD equation for rapidity evolution describing saturation effects at high energy admits universal asymptotic traveling-wave solutions when the nonlinear damping becomes effective. The asymptotic solutions fall in universality classes depending only on some specific properties of the solution of t...
0702131v2
2006-11-23
A coherent-state-based path integral for quantum mechanics on the Moyal plane
Inspired by a recent work that proposes using coherent states to evaluate the Feynman kernel in noncommutative space, we provide an independent formulation of the path-integral approach for quantum mechanics on the Moyal plane, with the transition amplitude defined between two coherent states of mean position coordinat...
0611254v1
2004-11-30
Development of singularities for the compressible Euler equations with external force in several dimensions
We consider solutions to the Euler equations in the whole space from a certain class, which can be characterized, in particular, by finiteness of mass, total energy and momentum. We prove that for a large class of right-hand sides, including the viscous term, such solutions, no matter how smooth initially, develop a si...
0411652v2
2006-03-04
Monotonicity properties of blow-up time for nonlinear Schrödinger equation: numerical tests
We consider the focusing nonlinear Schr\"{o}dinger equation, in the $L^2$-critical and supercritical cases. We investigate numerically the dependence of the blow-up time on a parameter in three cases: dependence upon the coupling constant, when the initial data are fixed; dependence upon the strength of a quadratic osc...
0603107v2
2003-06-23
Stochastic 'fuzzy confinement' of intrinsic localised modes
The long time diffusive behaviour of intrinsic localised modes (discrete breathers) in the discrete damped-driven sine-Gordon chain under Gaussian white noise (to simulate temperature) is studied. We present a theoretical model for an approximate description of the diffusion, derive an expression for the diffusion cons...
0306043v2
2005-06-08
Travelling kinks in discrete phi^4 models
In recent years, three exceptional discretizations of the phi^4 theory have been discovered [J.M. Speight and R.S. Ward, Nonlinearity 7, 475 (1994); C.M. Bender and A. Tovbis, J. Math. Phys. 38, 3700 (1997); P.G. Kevrekidis, Physica D 183, 68 (2003)] which support translationally invariant kinks, i.e. families of stati...
0506019v2
2006-09-21
Covariant response theory beyond RPA and its application
The covariant particle-vibration coupling model within the time blocking approximation is employed to supplement the Relativistic Random Phase Approximation (RRPA) with coupling to collective vibrations. The Bethe-Salpeter equation in the particle-hole channel with an energy dependent residual particle-hole (p-h) inter...
0609061v1
2005-11-17
Distance dependence of force and dissipation in non-contact atomic force microscopy on Cu(100) and Al(111)
The dynamic characteristics of a tip oscillating in the nc-AFM mode in close vicinity to a Cu(100)-surface are investigated by means of phase variation experiments in the constant amplitude mode. The change of the quality factor upon approaching the surface deduced from both frequency shift and excitation versus phase ...
0511151v1
1998-08-22
Quantum Coherence Oscillations in Antiferromagnetic Chains
Macroscopic quantum coherence oscillations in mesoscopic antiferromagnets may appear when the anisotropy potential creates a barrier between the antiferromagnetic states with opposite orientations of the Neel vector. This phenomenon is studied for the physical situation of the nuclear spin system of eight Xe atoms arra...
9808041v1
1998-12-09
The 1/N-expansion, quantum-classical correspondence and nonclassical states generation in dissipative higher-order anharmonic oscillators
We develop a method for the determination of thecdynamics of dissipative quantum systems in the limit of large number of quanta N, based on the 1/N-expansion of Heidmann et al. [ Opt. Commun. 54, 189 (1985) ] and the quantum-classical correspondence. Using this method, we find analytically the dynamics of nonclassical ...
9812019v2
2001-06-08
Modelling the Recoherence of Mesoscopic Superpositions in Dissipative Environments
A model is presented to describe the recently proposed experiment (J. Raimond, M. Brune and S. Haroche Phys. Rev. Lett {\bf 79}, 1964 (1997)) where a mesoscopic superposition of radiation states is prepared in a high-Q cavity which is coupled to a similar resonator. The dynamical coherence loss of such state in the a...
0106044v1
2001-12-20
Classical and Quantum-like approaches to Charged-Particle Fluids in a Quadrupole
A classical description of the dynamics of a dissipative charged-particle fluid in a quadrupole-like device is developed. It is shown that the set of the classical fluid equations contains the same information as a complex function satisfying a Schrodinger-like equation in which Planck's constant is replaced by the tim...
0112123v1
2002-03-25
Field quantization for open optical cavities
We study the quantum properties of the electromagnetic field in optical cavities coupled to an arbitrary number of escape channels. We consider both inhomogeneous dielectric resonators with a scalar dielectric constant $\epsilon({\bf r})$ and cavities defined by mirrors of arbitrary shape. Using the Feshbach projector ...
0203122v2
2007-01-29
Two-Mode Squeezed States and Entangled States of Two Mechanical Resonators
We study a device consisting of a dc-SQUID with two sections of its loop acting as two mechanical resonators. An analog of the parametric down-conversion process in quantum optics can be realized with this device. We show that a two-mode squeezed state can be generated for two overdamped mechanical resonators, where th...
0701209v3
2007-04-26
Type I singularities and the Phantom Menace
We consider the future dynamics of a transient phantom dominated phase of the universe in LQC and in the RS braneworld, which both have a non-standard Friedmann equation. We find that for a certain class of potentials, the Hubble parameter oscillates with simple harmonic motion in the LQC case and therefore avoids any ...
0704.3606v4
2007-05-03
Effective attraction induced by repulsive interaction in a spin-transfer system
In magnetic systems with dominating easy-plane anisotropy the magnetization can be described by an effective one dimensional equation for the in-plane angle. Re-deriving this equation in the presence of spin-transfer torques, we obtain a description that allows for a more intuitive understanding of spintronic devices' ...
0705.0508v1
2007-05-08
Particle-vibration coupling within covariant density functional theory
Covariant density functional theory, which has so far been applied only within the framework of static and time dependent mean field theory is extended to include Particle-Vibration Coupling (PVC) in a consistent way. Starting from a conventional energy functional we calculate the low-lying collective vibrations in Rel...
0705.1044v1
2007-06-15
Loschmidt echo and stochastic-like quantum dynamics of nano-particles
We investigate time evolution of prepared vibrational state (system) coupled to a reservoir with dense spectrum of its vibrational states. We assume that the reservoir has an equidistant spectrum, and the system - reservoir coupling matrix elements are independent of the reservoir states. The analytical solution manife...
0706.2333v1
2007-06-21
Spin pumping by a field-driven domain wall
We calculate the charge current in a metallic ferromagnet to first order in the time derivative of the magnetization direction. Irrespective of the microscopic details, the result can be expressed in terms of the conductivities of the majority and minority electrons and the non-adiabatic spin transfer torque parameter ...
0706.3160v3
2007-07-25
Polar phonons and spin-phonon coupling in HgCr2S4 and CdCr2S4
Polar phonons of HgCr2S4 and CdCr2S4 are studied by far-infrared spectroscopy as a function of temperature and external magnetic field. Eigenfrequencies, damping constants, effective plasma frequencies and Lyddane-Sachs-Teller relations, and effective charges are determined. Ferromagnetic CdCr2S4 and antiferromagnetic ...
0707.3776v1
2007-08-13
Ricci curvature and geodesic flows stability in Riemannian twisted flux tubes
Ricci and sectional curvatures of twisted flux tubes in Riemannian manifold are computed to investigate the stability of the tubes. The geodesic equations are used to show that in the case of thick tubes, the curvature of planar (Frenet torsion-free) tubes have the effect ct of damping the flow speed along the tube. St...
0708.1644v1
2007-08-21
Phase effects on synchronization by dynamical relaying in delay-coupled systems
Synchronization in an array of mutually coupled systems with a finite time-delay in coupling is studied using Josephson junction as a model system. The sum of the transverse Lyapunov exponents is evaluated as a function of the parameters by linearizing the equation about the synchronization manifold. The dependence of ...
0708.2759v4
2007-09-03
Transport properties controlled by a thermostat: An extended dissipative particle dynamics thermostat
We introduce a variation of the dissipative particle dynamics (DPD) thermostat that allows for controlling transport properties of molecular fluids. The standard DPD thermostat acts only on a relative velocity along the interatomic axis. Our extension includes the damping of the perpendicular components of the relative...
0709.0276v1
2007-09-07
Broadband dielectric response of CaCu3Ti4O12: From dc to the electronic transition regime
We report on phonon properties and electronic transitions in CaCu3Ti4O12, a material which reveals a colossal dielectric constant at room temperature without any ferroelectric transition. The results of far- and mid-infrared measurements are compared to those obtained by broadband dielectric and millimeter-wave spectro...
0709.1065v1
2007-10-07
Decays in Quantum Hierarchical Models
We study the dynamics of a simple model for quantum decay, where a single state is coupled to a set of discrete states, the pseudo continuum, each coupled to a real continuum of states. We find that for constant matrix elements between the single state and the pseudo continuum the decay occurs via one state in a certai...
0710.1403v1
2007-12-27
Dynamics of emergent Cooper pairing at finite temperatures
We study the time evolution of a system of fermions with pairing interactions at a finite temperature. The dynamics is triggered by an abrupt increase of the BCS coupling constant. We show that if initially the fermions are in a normal phase, the amplitude of the BCS order parameter averaged over the Boltzman distribut...
0712.4280v4
2008-04-14
Micromagnetics of single and double point contact spin torque oscillators
In this paper we numerically conduct micromagnetic modelling to optimize computational boundaries of magnetic thin-film elements applicable to single and double point contact spin torque nano-oscillators. Different boundary conditions have been introduced to compensate spin waves reflections at boundaries that are base...
0804.2119v1
2008-05-21
Non-equilibrium thermodynamic study of magnetization dynamics in the presence of spin-transfer torque
The dynamics of magnetization in the presence of spin-transfer torque was studied. We derived the equation for the motion of magnetization in the presence of a spin current by using the local equilibrium assumption in non-equilibrium thermodynamics. We show that, in the resultant equation, the ratio of the Gilbert damp...
0805.3306v1
2008-06-15
Stochastic acceleration of solitons for the nonlinear Schrödinger equation
The effective dynamics of solitons for the generalized nonlinear Schr\"odinger equation in a random potential is rigorously studied. It is shown that when the external potential varies slowly in space compared to the size of the soliton, the dynamics of the center of the soliton is almost surely described by Hamilton's...
0806.2439v1
2008-06-30
Beam Coupling Impedance Measurement and Mitigation for a TOTEM Roman Pot
The longitudinal and transverse beam coupling impedance of the first final TOTEM Roman Pot unit has been measured in the laboratory with the wire method. For the evaluation of transverse impedance the wire position has been kept constant, and the insertions of the RP were moved asymmetrically. With the original configu...
0806.4974v1
2009-02-25
B-mode CMB Polarization from Patchy Screening during Reionization
B-modes in CMB polarization from patchy reionization arise from two effects: generation of polarization from scattering of quadrupole moments by reionization bubbles, and fluctuations in the screening of E-modes from recombination. The scattering contribution has been studied previously, but the screening contribution ...
0902.4413v2
2009-03-10
Phonon-phonon interactions and phonon damping in carbon nanotubes
We formulate and study the effective low-energy quantum theory of interacting long-wavelength acoustic phonons in carbon nanotubes within the framework of continuum elasticity theory. A general and analytical derivation of all three- and four-phonon processes is provided, and the relevant coupling constants are determi...
0903.1771v2
2009-03-24
Chaotic thermalization in Yang-Mills-Higgs theory on a spacial lattice
We analyze the Hamiltonian time evolution of classical SU(2) Yang-Mills-Higgs theory with a fundamental Higgs doublet on a spacial lattice. In particular, we study energy transfer and equilibration processes among the gauge and Higgs sectors, calculate the maximal Lyapunov exponents under randomized initial conditions ...
0903.3990v2
2009-05-01
Spin excitations in a monolayer scanned by a magnetic tip
Energy dissipation via spin excitations is investigated for a hard ferromagnetic tip scanning a soft magnetic monolayer. We use the classical Heisenberg model with Landau-Lifshitz-Gilbert (LLG)-dynamics including a stochastic field representing finite temperatures. The friction force depends linearly on the velocity (p...
0905.0112v2
2009-05-18
Long-term evolution and gravitational wave radiation of neutron stars with differential rotation induced by r-modes
In a second-order r-mode theory, S'a & Tom'e found that the r-mode oscillation in neutron stars (NSs) could induce stellar differential rotation, which leads to a saturation state of the oscillation spontaneously. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolutions, we ca...
0905.2804v1
2009-05-22
Quantum dissipative Brownian motion and the Casimir effect
We explore an analogy between the thermodynamics of a free dissipative quantum particle and that of an electromagnetic field between two mirrors of finite conductivity. While a free particle isolated from its environment will effectively be in the high-temperature limit for any nonvanishing temperature, a finite coupli...
0905.3608v1
2009-06-24
Suppression of friction by mechanical vibrations
Mechanical vibrations are known to affect frictional sliding and the associated stick-slip patterns causing sometimes a drastic reduction of the friction force. This issue is relevant for applications in nanotribology and to understand earthquake triggering by small dynamic perturbations . We study the dynamics of re...
0906.4504v1
2009-10-17
Zero and First Sound in Normal Fermi Systems
On the basis of a moment method, general solutions of a linearized Boltzmann equation for a normal Fermi system are investigated. In particular, we study the sound velocities and damping rates as functions of the temperature and the coupling constant. In the extreme limits of collisionless and hydrodynamic regimes, eig...
0910.3283v1
2010-02-11
Spin drag in an ultracold Fermi gas on the verge of a ferromagnetic instability
Recent experiments [Jo et al., Science 325, 1521 (2009)] have presented evidence of ferromagnetic correlations in a two-component ultracold Fermi gas with strong repulsive interactions. Motivated by these experiments we consider spin drag, i.e., frictional drag due to scattering of particles with opposite spin, in such...
1002.2371v2
2010-03-12
Longitudinal dielectric permettivity of quantum Maxwell collisional plasmas
The kinetic equation of Wigner -- Vlasov -- Boltzmann with collision integral in relaxation BGK (Bhatnagar, Gross and Krook) form in coordinate space for quantum non--degenerate (Maxwellian) collisional plasma is used. Exact expression (within the limits of considered model) is found. The analysis of longitudinal diele...
1003.2531v1
2010-04-11
Quantum noise reduction using a cavity with a Bose Einstein condensate
We study an optomechanical system in which the collective density excitations (Bogoliubov modes) of a Bose Einstein condensate (BEC) is coupled to a cavity field. We show that the optical force changes the frequency and the damping constant of the collective density excitations of the BEC. We further analyze the occurr...
1004.1813v1
2010-07-01
Directed motion of domain walls in biaxial ferromagnets under the influence of periodic external magnetic fields
Directed motion of domain walls (DWs) in a classical biaxial ferromagnet placed under the influence of periodic unbiased external magnetic fields is investigated. Using the symmetry approach developed in this article the necessary conditions for the directed DW motion are found. This motion turns out to be possible if ...
1007.0090v2
2010-08-23
Perturbations of Dark Solitons
A method for approximating dark soliton solutions of the nonlinear Schrodinger equation under the influence of perturbations is presented. The problem is broken into an inner region, where core of the soliton resides, and an outer region, which evolves independently of the soliton. It is shown that a shelf develops aro...
1008.3756v1
2010-08-30
Directed transport in equilibrium
We investigate a symmetry broken dimer constrained to move in a particular direction when in contact with a heat-bath at a constant temperature. The dimer is not driven by any external force. The system gains kinetic energy from the heat-bath. The symmetry broken system can use this energy in directed transport. At the...
1008.4992v8
2010-08-30
Scalar graviton in the healthy extension of Hořava-Lifshitz theory
In this note we study the linear dynamics of scalar graviton in a de Sitter background in the infrared limit of the healthy extension of Ho\v{r}ava-Lifshitz gravity with the dynamical critical exponent $z=3$. Both our analytical and numerical results show that the non-zero Fourier modes of scalar graviton oscillate wit...
1008.5048v3
2010-09-17
Time resolved X-ray Resonant Magnetic Scattering in reflection geometry
We present a new setup to measure element-selective magnetization dynamics using the ALICE chamber (RSI \textbf{74}, 4048 (2003)) at the BESSY II synchrotron at the Helmholtz-Zentrum Berlin. A magnetic field pulse serves as excitation, and the magnetization precession is probed by element selective X-ray Resonant Magne...
1009.3389v1
2011-02-07
Buckling and longterm dynamics of a nonlinear model for the extensible beam
This work is focused on the longtime behavior of a non linear evolution problem describing the vibrations of an extensible elastic homogeneous beam resting on a viscoelastic foundation with stiffness k>0 and positive damping constant. Buckling of solutions occurs as the axial load exceeds the first critical value, \bet...
1102.1259v1
2011-02-17
Effects of disorder on magnetic vortex gyration
A vortex gyrating in a magnetic disk has two regimes of motion in the presence of disorder. At large gyration amplitudes, the vortex core moves quasi-freely through the disorder potential. As the amplitude decreases, the core can become pinned at a particular point in the potential and precess with a significantly incr...
1102.3711v1
2011-03-30
Spin motive forces due to magnetic vortices and domain walls
We study spin motive forces, i.e, spin-dependent forces, and voltages induced by time-dependent magnetization textures, for moving magnetic vortices and domain walls. First, we consider the voltage generated by a one-dimensional field-driven domain wall. Next, we perform detailed calculations on field-driven vortex dom...
1103.5858v3
2011-05-02
Ultrasoft Fermionic Mode in Yukawa Theory at High Temperature
We explore whether an ultrasoft fermionic mode exists at extremely high temperature in Yukawa theory with massless fermion (coupling constant is g). We find that the fermion propagator has a pole at \omega = \pm p/3-i\zeta, for ultrasoft momentum p, where \zeta \sim g^4T ln 1/g, and the residue is Z \sim g^2. It is sho...
1105.0423v2
2011-07-17
Spin current induced magnetization oscillations in a paramagnetic disc
When electron spins are injected uniformly into a paramagnetic disc, they can precess along the demagnetizing field induced by the resulting magnetic moment. Normally this precession damps out by virtue of the spin relaxation which is present in paramagnetic materials. We propose a new mechanism to excite a steady-stat...
1107.3288v1
2011-11-09
Numerical stability of the Z4c formulation of general relativity
We study numerical stability of different approaches to the discretization of a conformal decomposition of the Z4 formulation of general relativity. We demonstrate that in the linear, constant coefficient regime a novel discretization for tensors is formally numerically stable with a method of lines time-integrator. We...
1111.2177v1
2011-11-16
Evolution of the spectrum and the metal-insulator transition in local approximations for many-electron models
In the framework of the many-electron s-d exchange model and Hubbard model, self-consistent equations are derived for the one-particle retarded Green's function in the many-electron Hubbard X-operator representation. We analyze the general structure of the single-site approximations and their connection with the cohere...
1111.3751v1
2011-11-22
On the Kramers-Kronig transform with logarithmic kernel for the reflection phase in the Drude model
We use the Kramers-Kronig transform (KKT) with logarithmic kernel to obtain the reflection phase and, subsequently, the complex refractive index of a bulk mirror from reflectance. However, there remains some confusion regarding the formulation for this analysis. Assuming the damped Drude model for the dielectric consta...
1111.5139v1
2011-12-22
A continuous model for turbulent energy cascade
In this paper we introduce a new PDE model in frequency space for the inertial energy cascade that reproduces the classical scaling laws of Kolmogorov's theory of turbulence. Our point of view is based upon studying the energy flux through a continuous range of scales rather than the discrete set of dyadic scales. The ...
1112.5376v1
2012-01-17
Magnetic vortex echoes: application to the study of arrays of magnetic nanostructures
We propose the use of the gyrotropic motion of vortex cores in nanomagnets to produce a magnetic echo, analogous to the spin echo in NMR. This echo occurs when an array of nanomagnets, e.g., nanodisks, is magnetized with an in-plane (xy) field, and after a time \tau a field pulse inverts the core magnetization; the ech...
1201.3553v1
2012-01-30
Non-contact Friction and Relaxational Dynamics of Surface Defects
Motion of cantilever near sample surfaces exhibits additional friction even before two bodies come into mechanical contact. Called non-contact friction (NCF), this friction is of great practical importance to the ultrasensitive force detection measurements. Observed large NCF of a micron-scale cantilever found anomalou...
1201.6378v1
2012-02-15
Current-induced motion of a transverse magnetic domain wall in the presence of spin Hall effect
We theoretically study the current-induced dynamics of a transverse magnetic domain wall in bi-layer nanowires consisting of a ferromagnet on top of a nonmagnet having strong spin-orbit coupling. Domain wall dynamics is characterized by two threshold current densities, $J_{th}^{WB}$ and $J_{th}^{REV}$, where $J_{th}^{W...
1202.3450v1
2012-02-29
Bimagnon studies in cuprates with Resonant Inelastic X-ray Scattering at the O K edge. II - The doping effect in La2-xSrxCuO4
We present RIXS data at O K edge from La2-xSrxCuO4 vs. doping between x=0.10 and x=0.22 with attention to the magnetic excitations in the Mid-Infrared region. The sampling done by RIXS is the same as in the undoped cuprates provided the excitation is at the first pre-peak induced by doping. Note that this excitation en...
1202.6608v2
2012-03-08
A Self-Consistent Marginally Stable State for Parallel Ion Cyclotron Waves
We derive an equation whose solutions describe self-consistent states of marginal stability for a proton-electron plasma interacting with parallel-propagating ion cyclotron waves. Ion cyclotron waves propagating through this marginally stable plasma will neither grow nor damp. The dispersion relation of these waves, {\...
1203.1938v1
2012-03-14
QSO 0347-383 and the invariance of m_p/m_e in the course of cosmic time
The variation of the dimensionless fundamental physical constant mu = m_p/m_e (the proton to electron mass ratio) can be constrained via observation of Lyman and Werner lines of molecular hydrogen in the spectra of damped Lyman alpha systems (DLAs) in the line of sight to distant QSOs. Drawing on VLT-UVES high resoluti...
1203.3193v1
2012-03-26
Local electric current correlation function in an exponentially decaying magnetic field
The effect of an exponentially decaying magnetic field on the dynamics of Dirac fermions in 3+1 dimensions is explored. The spatially decaying magnetic field is assumed to be aligned in the third direction, and is defined by {\mathbf{B}}(x)=B(x){\mathbf{e}}_{z}, with B(x)=B_{0}e^{-\xi\ x/\ell_{B}}. Here, \xi\ is a dime...
1203.5634v2
2012-07-09
Thermal vortex dynamics in thin circular ferromagnetic nanodisks
The dynamics of gyrotropic vortex motion in a thin circular nanodisk of soft ferromagnetic material is considered. The demagnetization field is calculated using two-dimensional Green's functions for the thin film problem and fast Fourier transforms. At zero temperature, the dynamics of the Landau-Lifshitz-Gilbert equat...
1207.2192v2
2012-07-26
Transient noise spectra in resonant tunneling setups: Exactly solvable models
We investigate the transient evolution of finite-frequency current noise after abrupt switching on of the tunneling coupling in two paradigmatic, exactly solvable models of mesoscopic physics: the resonant level model and the Majorana resonant level model, which emerges as an effective model for a Kondo quantum dot at ...
1207.6222v2
2012-12-06
Time-dependent spherically symmetric covariant Galileons
We study spherically symmetric solutions of the cubic covariant Galileon model in curved spacetime in presence of a matter source, in the test scalar field approximation. We show that a cosmological time evolution of the Galileon field gives rise to an induced matter-scalar coupling, due to the Galileon-graviton kineti...
1212.1394v2
2012-12-13
Astrophysical tests of atomic data important for stellar Mg abundance determinations
Magnesium abundances of cool stars with different metallicities are important for understanding the galactic chemical evolution. This study tests atomic data used in stellar magnesium abundance analyses. We evaluate non-local thermodynamical equilibrium (NLTE) line formation for Mg I using the most up-to-date theoretic...
1212.3192v1
2013-01-14
Universal Properties of the Higgs Resonance in (2+1)-Dimensional U(1) Critical Systems
We present spectral functions for the magnitude squared of the order parameter in the scaling limit of the two-dimensional superfluid to Mott insulator quantum phase transition at constant density, which has emergent particle-hole symmetry and Lorentz invariance. The universal functions for the superfluid, Mott insulat...
1301.3139v2
2013-03-05
Dynamics and relaxation in spin nematics
We study dynamics and relaxation of elementary excitations (magnons) in the spin nematic (quadrupole ordered) phase of S=1 magnets. We develop a general phenomenological theory of spin dynamics and relaxation for spin-1 systems. Results of the phenomenological approach are compared to those obtained by microscopic calc...
1303.1194v2
2013-03-11
Ultrasoft fermion mode and off-diagonal Boltzmann equation in quark-gluon plasma at high temperature
We derive the generalized Boltzmann equation (GBE) near equilibrium from the Kadanoff-Baym equation for quark excitation with ultrasoft momentum (~g^2T, g: coupling constant, T: temperature) in quantum chromodynamics (QCD) at extremely high T, and show that the equation is equivalent to the self-consistent equation der...
1303.2684v1
2013-03-27
Superluminal Waves and the Structure of Pulsar Wind Termination Shocks
The termination shock of a pulsar wind is located roughly where the ram pressure matches that of the surrounding medium. Downstream of the shock, MHD models of the diffuse nebular emission suggest the plasma is weakly magnetized. However, the transition from a Poynting-dominated MHD wind to a particle-dominated flow is...
1303.6781v1
2013-04-26
Strong magnon softening in tetragonal FeCo compounds
Magnons play an important role in fast precessional magnetization reversal processes serving as a heat bath for dissipation of the Zeeman energy and thus being responsible for the relaxation of magnetization. Employing \emph{ab initio} many-body perturbation theory we studied the magnon spectra of the tetragonal FeCo c...
1304.7091v1
2013-07-01
Quasinormal modes of charged dilaton black holes and their entropy spectra
In this study, we employ the scalar perturbations of the charged dilaton black hole (CDBH) found by Chan, Horne and Mann (CHM), and described with an action which emerges in the low-energy limit of the string theory. A CDBH is neither asymptotically flat (AF) nor non-asymptotically flat (NAF) spacetime. Depending on th...
1307.0340v2
2013-07-10
The Contrastive analysis of observation data between HLS and DSQ water tube clinometers in Jingxian seismicstation
A set of HLS was installed in JingXian seismicstation for the tidal correction of observations from HLS. Harmonic analysis of the data recorded by HLS and DSQ water tube clinometers in JingXian seismicstation and contrastive analysis of the results are completed. The tilt tide can be well reflected in the data of the b...
1307.2680v2
2013-07-26
Transients in the Synchronization of Oscillator Arrays
The purpose of this note is threefold. First we state a few conjectures that allow us to rigorously derive a theory which is asymptotic in N (the number of agents) that describes transients in large arrays of (identical) linear damped harmonic oscillators in R with completely decentralized nearest neighbor interaction....
1308.4919v4
2013-09-05
Amplification and passing through the barrier of the exciton condensed phase pulse in double quantum wells
The peculiarities and the possibility of a control of exciton condensed pulse movement in semiconductor double quantum well under the slot in the metal electrode are studied. The condensed phase is considered phenomenologically with the free energy in Landau-Ginzburg form taking into account the finite value of the exc...
1309.1297v1