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2013-09-21
Patterns formation in axially symmetric Landau-Lifshitz-Gilbert-Slonczewski equations
The Landau-Lifshitz-Gilbert-Slonczewski equation describes magnetization dynamics in the presence of an applied field and a spin polarized current. In the case of axial symmetry and with focus on one space dimension, we investigate the emergence of space-time patterns in the form of wavetrains and coherent structures, ...
1309.5523v4
2013-10-09
Symmetry Analysis in Linear Hydrodynamic Stability Theory: Classical and New Modes in Linear Shear
We present a symmetry classification of the linearised Navier-Stokes equations for a two-dimensional unbounded linear shear flow of an incompressible fluid. The full set of symmetries is employed to systematically derive invariant ansatz functions. The symmetry analysis grasps three approaches. Two of them are existing...
1310.2650v1
2013-10-23
Spectroscopic investigation of local mechanical impedance of living cells
The mechanical properties of PC12 living cells have been studied at the nanoscale with a Force Feedback Microscope using two experimental approaches. Firstly, the local mechanical impedance of the cell membrane has been mapped simultaneously to the cell morphology at constant force. As the force of the interaction is g...
1310.6201v1
2013-10-23
Using an artificial electric field to create the analog of the red spot of Jupiter in light-heavy Fermi-Fermi mixtures of ultracold atoms
Time-of-flight images are a common tool in ultracold atomic experiments, employed to determine the quasimomentum distribution of the interacting particles. If one introduces a constant artificial electric field, then the quasimomentum distribution evolves in time as Bloch oscillations are generated in the system and th...
1310.6350v1
2013-11-21
Note on the super inflation in loop quantum cosmology
Phenomenological effect of the super-inflation in loop quantum cosmology (LQC) is discussed. We investigate the case that the Universe is filled with the interacting field between massive scalar field and radiation. Considering the damping coefficient $\Gamma$ as a constant, the changes of the scale factor during super...
1311.5325v1
2013-12-10
Delaying the waterfall transition in warm hybrid inflation
We analyze the dynamics and observational predictions of supersymmetric hybrid inflation in the warm regime, where dissipative effects are mediated by the waterfall fields and their subsequent decay into light degrees of freedom. This produces a quasi-thermal radiation bath with a slowly-varying temperature during infl...
1312.2961v1
2013-12-11
Modelling of the optical properties of silver with use of six fitting parameters
We propose a realistic model of the optical properties of silver, in which inter-band transition with a threshold energy of ~ 4 eV is described phenomenologically by an ensemble of oscillators with same damping constant and a certain distribution of resonant frequencies in the interband transition threshold to infinity...
1312.3100v1
2014-02-13
Tailoring optical fields emitted by nanometric sources
Here we study a simple way of controlling the emitted fields of sub-wavelength nanometric sources. The system consists of arrays of nanoparticles (NPs) embedded in optical active media. The key concept is the careful tuning of NP's damping factors, which changes the eigenmode's decay rates of the whole array. This, at ...
1402.3184v1
2014-02-25
Kinetic theory for a mobile impurity in a degenerate Tonks-Girardeau gas
A kinetic theory describing the motion of an impurity particle in a degenerate Tonks-Girardeau gas is presented. The theory is based on the one-dimensional Boltzmann equation. An iterative procedure for solving this equation is proposed, leading to the exact solution in number of special cases and to an approximate sol...
1402.6362v2
2014-02-28
Probing the critical behavior in the evolution of GDR width at very low temperatures in A~100 mass region
The influence of giant dipole resonance (GDR) induced quadrupole moment on GDR width at low temperatures is investigated experimentally by measuring GDR width systematically in the unexplored temperature range $T$=0.8-1.5 MeV, for the first time, in $A$ $\sim$ 100 mass region. The measured GDR widths, using alpha induc...
1402.7210v1
2014-03-19
Kinetic description of wave induced plasma flow in the radio frequency domain
A model for ICRH induced flows in the presence of a strong magnetic field is presented. These flows are the finite temperature counterpart of flows existing in cold plasmas described e.g. in [D. Van Eester et al., Plasma Phys. Control. Fusion 55 (2013) 025002] and thus do not rely on the waves being damped. The kinetic...
1403.4770v1
2014-04-04
Irreversible Thermodynamics of the Universe: Constraints from Planck Data
The present work deals with irreversible Universal thermodynamics. The homogenous and isotropic flat model of the universe is chosen as open thermodynamical system and non-equilibrium thermodynamics comes into picture due to the mechanism of particle creation. For simplicity, entropy flow is considered only due to heat...
1404.1220v1
2014-04-18
Transport Properties of Dirac Ferromagnet
We propose a model ferromagnet based on the Dirac Hamiltonian in three spatial dimensions, and study its transport properties which include anisotropic magnetoresistance (AMR) and anomalous Hall (AH) effect. This relativistic extension allows two kinds of ferromagnetic order parameters, denoted by $\bm{M}$ and $\bm{S}$...
1404.4741v2
2014-05-21
Spectroscopy of Rindler Modified Schwarzschild Black Hole
We study quasinormal modes (QNMs) of uncharged Grumiller black hole (GBH). This massive BH has a Rindler acceleration $a$, and hence it is also called Rindler modified Schwarzschild BH. After reducing the radial equation of the massless Klein-Gordon equation to the Zerilli equation, we compute the complex frequencies o...
1405.5388v1
2014-08-08
Ambipolar diffusion in smoothed particle magnetohydrodynamics
In partially ionised plasmas, the magnetic field can become decoupled from the neutral gas and diffuse through it in a process known as ambipolar diffusion. Although ambipolar diffusion has been implemented in several grid codes, we here provide an implementation in smoothed particle magnetohydrodynamics (SPMHD). We us...
1408.1807v1
2014-10-05
Finite-time stabilization of a network of strings
We investigate the finite-time stabilization of a tree-shaped network of strings. Transparent boundary conditions are applied at all the external nodes. At any internal node, in addition to the usual continuity conditions, a modified Kirchhoff law incorporating a damping term $\alpha u_t$ with a coefficient $\alpha$ th...
1410.1122v1
2014-10-22
Spin current generation from sputtered Y3Fe5O12 films
Spin current injection from sputtered yttrium iron garnet (YIG) films into an adjacent platinum layer has been investigated by means of the spin pumping and the spin Seebeck effects. Films with a thickness of 83 and 96 nanometers were fabricated by on-axis magnetron rf sputtering at room temperature and subsequent post...
1410.5987v1
2014-11-03
Experimental Demonstration of the Co-existence of the Spin Hall and Rashba Effects in beta-Tantalum/Ferromagnet Bilayers
We have measured the spin torques of beta-Tantalum / Co20Fe60B20 bilayers versus Ta thickness at room temperature using an FMR technique. The spin Hall coefficient was calculated both from the observed change in damping coefficient of the ferromagnet with Ta thickness, and from the ratio of the symmetric and anti-symme...
1411.0601v1
2014-12-01
Dissipation due to pure spin-current generated by spin pumping
Based on spin-dependent transport theory and thermodynamics, we develop a generalized theory of the Joule heating in the presence of a spin current. Along with the conventional Joule heating consisting of an electric current and electrochemical potential, it is found that the spin current and spin accumulation give an ...
1412.0688v1
2014-12-08
Higgs mode in the quench dynamics of a confined ultracold Fermi gas in the BCS regime
The Higgs amplitude mode of the order parameter of an ultracold confined Fermi gas in the BCS regime after a quench of the coupling constant is analyzed theoretically. Characteristic features are a damped oscillation which at a certain transition time changes into a rather irregular dynamics. We compare the numerical s...
1412.2591v1
2014-12-16
Dynamics of reversals and condensates in 2D Kolmogorov flows
We present direct numerical simulations of the different two-dimensional flow regimes generated by a constant spatially periodic forcing balanced by viscous dissipation and large scale drag with a dimensionless damping rate $1/Rh$. The linear response to the forcing is a $6\times6$ square array of counter-rotating vort...
1412.4959v1
2015-01-14
Predissociation dynamics of lithium iodide
The predissociation dynamics of lithium iodide (LiI) in the first excited A-state is investigated for molecules in the gas phase and embedded in helium nanodroplets, using femtosecond pump-probe photoionization spectroscopy. In the gas phase, the transient Li+ and LiI+ ion signals feature damped oscillations due to the...
1501.03327v1
2015-01-15
Dynamics and performance of clock pendulums
We analyze the dynamics of a driven, damped pendulum as used in mechanical clocks. We derive equations for the amplitude and phase of the oscillation, on time scales longer than the pendulum period. The equations are first order ODEs and permit fast simulations of the joint effects of circular and escapement errors, fr...
1501.03673v1
2015-01-21
Controllable chaotic dynamics in a nonlinear fiber ring resonators with balanced gain and loss
We show the possibility of controlling the dynamical behavior of a single fiber ring (SFR) resonator system with the fiber being an amplified (gain) channel and the ring being attenuated (loss) nonlinear dielectric medium. Our model is based on the simple alterations in the parity time symmetric synthetic coupler struc...
1501.05187v2
2015-01-30
Head-to-Head Domain Wall Structures in Wide Permalloy Strips
We analyze the equilibrium micromagnetic domain wall structures encountered in Permalloy strips of a wide range of thicknesses and widths, with strip widths up to several micrometers. By performing an extensive set of micromagnetic simulations, we show that the equilibrium phase diagram of the domain wall structures ex...
1501.07731v1
2015-03-19
On the efficiency of heat engines at the micro-scale and below
We investigate the thermodynamic efficiency of sub-micro-scale heat engines operating under the conditions described by over-damped stochastic thermodynamics. We prove that at maximum power the efficiency obeys for constant isotropic mobility the universal law $\eta=2\,\eta_{C}/(4-\eta_{C})$ where $\eta_{C}$ is the eff...
1503.05788v2
2015-03-26
Thermophoresis of an Antiferromagnetic Soliton
We study dynamics of an antiferromagnetic soliton under a temperature gradient. To this end, we start by phenomenologically constructing the stochastic Landau-Lifshitz-Gilbert equation for an antiferromagnet with the aid of the fluctuation-dissipation theorem. We then derive the Langevin equation for the soliton's cent...
1503.07854v2
2015-04-09
Thinning and thickening in active microrheology
When pulling a probe particle in a many-particle system with fixed velocity, the probe's effective friction, defined as average pulling force over its velocity, $\gamma_{eff}:=\langle F_{ex}\rangle/u$, first keeps constant (linear response), then decreases (thinning) and finally increases (thickening). We propose a thr...
1504.02277v1
2015-06-09
Sensitivity analysis for shape optimization of a focusing acoustic lens in lithotripsy
We are interested in shape sensitivity analysis for an optimization problem arising in medical applications of high intensity focused ultrasound. The goal is to find the optimal shape of a focusing acoustic lens so that the desired acoustic pressure at a kidney stone is achieved. Coupling of the silicone acoustic lens ...
1506.02781v1
2015-06-27
The Quasi-normal Modes of Charged Scalar Fields in Kerr-Newman black hole and Its Geometric Interpretation
It is well-known that there is a geometric correspondence between high-frequency quasi-normal modes (QNMs) and null geodesics (spherical photon orbits). In this paper, we generalize such correspondence to charged scalar field in Kerr-Newman space-time. In our case, the particle and black hole are all charged, so one sh...
1506.08276v2
2015-07-05
Representation of the Fourier transform as a weighted sum of the complex error functions
In this paper we show that a methodology based on a sampling with the Gaussian function of kind $h\,{e^{ - {{\left( {t/c} \right)}^2}}}/\left( {{c}\sqrt \pi } \right)$, where ${c}$ and $h$ are some constants, leads to the Fourier transform that can be represented as a weighted sum of the complex error functions. Due to...
1507.01241v3
2015-07-17
Oscillatory Growth: A Phenomenological View
In this communication, the approach of phenomenological universalities of growth are considered to describe the behaviour of a system showing oscillatory growth. Two phenomenological classes are proposed to consider the behaviour of a system in which oscillation of a property may be observed. One of them is showing osc...
1507.04833v1
2015-07-29
Gravitational, shear and matter waves in Kantowski-Sachs cosmologies
A general treatment of vorticity-free, perfect fluid perturbations of Kantowski-Sachs models with a positive cosmological constant are considered within the framework of the 1+1+2 covariant decomposition of spacetime. The dynamics is encompassed in six evolution equations for six harmonic coefficients, describing gravi...
1507.08300v2
2015-08-04
Scalar Perturbations of two-dimensional Horava-Lifshitz Black Holes
In this article, we study the stability of black hole solutions found in the context of dilatonic Horava-Lifshitz gravity in $1+1$ dimensions by means of the quasinormal modes approach. In order to find the corresponding quasinormal modes, we consider the perturbations of massive and massless scalar fields minimally co...
1508.00650v2
2015-09-16
Outgoing electromagnetic power induced from pair plasma falling into a rotating black hole
We examine energy conversion from accreting pair plasma to outgoing Poynting flux by black hole rotation. Our approach is based on a two-fluid model consisting of collisionless pair plasma. The electric potential is not constant along magnetic field lines, unlike an ideal magnetohydrodynamics approximation. We show how...
1509.04793v1
2015-09-16
Hydrodynamics, resurgence and trans-asymptotics
The second-order hydrodynamical description of a homogeneous conformal plasma that undergoes a boost- invariant expansion is given by a single nonlinear ordinary differential equation, whose resurgent asymptotic properties we study, developing further the recent work of Heller and Spalinski [Phys. Rev. Lett. 115, 07250...
1509.05046v1
2015-10-30
Anisotropic characteristics of the Kraichnan direct cascade in two-dimensional hydrodynamic turbulence
Statistical characteristics of the Kraichnan direct cascade for two-dimensional hydrodynamic turbulence are numerically studied (with spatial resolution $8192\times 8192$) in the presence of pumping and viscous-like damping. It is shown that quasi-shocks of vorticity and their Fourier partnerships in the form of jets i...
1510.09052v1
2015-11-10
On the global solution of 3-D MHD system with initial data near equilibrium
In this paper, we prove the global existence of smooth solutions to the three-dimensional incompressible magneto-hydrodynamical system with initial data close enough to the equilibrium state, $(e_3,0).$ Compared with the the previous works \cite{XLZMHD1, XZ15}, here we present a new Lagrangian formulation of the system...
1511.02978v1
2016-01-10
Interfacial Dzyaloshinskii-Moriya interaction, surface anisotropy energy,and spin pumping at spin orbit coupled Ir/Co interface
The interfacial Dzyaloshinskii-Moriya interaction (iDMI), surface anisotropy energy, and spin pumping at the Ir/Co interface are experimentally investigated by performing Brillouin light scattering. Contrary to previous reports, we suggest that the sign of the iDMI at the Ir/Co interface is the same as in the case of t...
1601.02210v3
2016-01-16
Spin-orbit torque in Cr/CoFeAl/MgO and Ru/CoFeAl/MgO epitaxial magnetic heterostructures
We study the spin-orbit torque (SOT) effective fields in Cr/CoFeAl/MgO and Ru/CoFeAl/MgO magnetic heterostructures using the adiabatic harmonic Hall measurement. High-quality perpendicular-magnetic-anisotropy CoFeAl layers were grown on Cr and Ru layers. The magnitudes of the SOT effective fields were found to signific...
1601.04164v1
2016-01-31
Role of epistasis on the fixation probability of a non-mutator in an adapted asexual population
The mutation rate of a well adapted population is prone to reduction so as to have a lower mutational load. We aim to understand the role of epistatic interactions between the fitness affecting mutations in this process. Using a multitype branching process, the fixation probability of a single non-mutator emerging in a...
1602.00282v2
2016-02-21
Global Finite-Time Attitude Tracking via Quaternion Feedback
This paper addresses the attitude tracking of a rigid body using a quaternion description. Global finite-time attitude controllers are designed with three types of measurements, namely, full states, attitude plus constant-biased angular velocity, and attitude only. In all three scenarios hybrid control techniques are u...
1602.06492v3
2016-04-12
Quasinormal modes and a new instability of Einstein-Gauss-Bonnet black holes in the de Sitter world
Analysis of time-domain profiles for gravitational perturbations shows that Gauss-Bonnet black holes in a de Sitter world possess a new kind of dynamical instability which does not take place for asymptotically flat Einstein-Gauss-Bonnet black holes. The new instability is in the gravitational perturbations of the scal...
1604.03604v2
2016-04-29
Friedmann dynamics recovered from compactified Einstein-Gauss-Bonnet cosmology
In this paper cosmological dynamics in Einstein-Gauss-Bonnet gravity with a perfect fluid source in arbitrary dimension is studied. A systematic analysis is performed for the case that the theory does not admit maximally symmetric solutions. Considering two independent scale factors, namely one for the three dimensiona...
1605.00041v1
2016-05-05
Pulse excitation to continuous-wave excitation in a low-dimensional interacting quantum system
Real-time dynamics in one-dimensional transverse Ising model coupled with the time-dependent oscillating field is analyzed by using the infinite time-evolving block decimation algorithm and the Floquet theory. In particular, the transient dynamics induced by the pulse field and their connections to the dynamics by a co...
1605.01537v1
2016-06-20
Electronic friction near metal surfaces: a case where molecule-metal couplings depend on nuclear coordinates
We derive an explicit form for the electronic friction as felt by a molecule near a metal surface for the general case that molecule-metal couplings depend on nuclear coordinates. Our work generalizes a previous study by von Oppen et al [Beilstein Journal of Nanotechnology, 3, 144, 2012], where we now go beyond the Con...
1606.06110v1
2016-07-13
Inductive intrinsic localized modes in a 1D nonlinear electric transmission line
The experimental properties of intrinsic localized modes (ILM) have long been compared with theoretical dynamical lattice models that make use of nonlinear onsite and/or nearest neighbor intersite potentials. Here it is shown for a 1-D lumped electrical transmission line a nonlinear inductive component in an otherwise ...
1607.03962v1
2016-08-10
Glassy Dynamics of Brownian Particles with Velocity-Dependent Friction
We consider a two-dimensional model system of Brownian particles in which slow particles are accelerated while fast particles are damped. The motion of the individual particles are described by a Langevin equation with Rayleigh-Helmholtz velocity dependent friction. In case of noninteracting particles, the time evoluti...
1608.03162v1
2016-09-05
Coarsening dynamics of topological defects in thin Permalloy films
We study the dynamics of topological defects in the magnetic texture of rectangular Permalloy thin film elements during relaxation from random magnetization initial states. Our full micromagnetic simulations reveal complex defect dynamics during relaxation towards the stable Landau closure domain pattern, manifested as...
1609.01094v1
2016-09-27
Anomalous Feedback and Negative Domain Wall Resistance
Magnetic induction can be regarded as a negative feedback effect, where the motive-force opposes the change of magnetic flux that generates the motive-force. In artificial electromagnetics emerging from spintronics, however, this is not necessarily the case. By studying the current-induced domain wall dynamics in a cyl...
1609.08250v1
2016-10-19
Coupling of Damped and Growing Modes in Unstable Shear Flow
Analysis of the saturation of the Kelvin-Helmholtz (KH) instability is undertaken to determine the extent to which the conjugate linearly stable mode plays a role. For a piecewise-continuous mean flow profile with constant shear in a fixed layer, it is shown that the stable mode is nonlinearly excited, providing an inj...
1610.06142v4
2016-11-05
Number of Wavevectors for Each Frequency in a Periodic Structure
Periodic structures have interesting acoustic and vibration properties making them suitable for a wide variety of applications. In a periodic structure, the number of frequencies for each wavevector depends on the degree of freedom of the unit cell. In this paper, we investigate the number of wavevectors for each frequ...
1611.01677v1
2016-11-22
On the symplectic covariance and interferences of time-frequency distributions
We study the covariance property of quadratic time-frequency distributions with respect to the action of the extended symplectic group. We show how covariance is related, and in fact in competition, with the possibility of damping the interferences which arise due to the quadratic nature of the distributions. We also s...
1611.07442v1
2017-01-05
Excitation and detection of short-waved spin waves in ultrathin Ta/CoFeB/MgO-layer system suitable for spin-orbit-torque magnonics
We report on the excitation and detection of short-waved spin waves with wave vectors up to about $40\,\mathrm{rad}\,\mu\mathrm{m}^{-1}$ in spin-wave waveguides made from ultrathin, in-plane magnetized Co$_{8}$Fe$_{72}$B$_{20}$ (CoFeB). The CoFeB is incorporated in a layer stack of Ta/CoFeB/Mgo, a layer system featurin...
1701.01399v1
2017-03-28
Temperature dependent magnetic damping of yttrium iron garnet spheres
We investigate the temperature dependent microwave absorption spectrum of an yttrium iron garnet sphere as a function of temperature (5 K to 300 K) and frequency (3 GHz to 43.5 GHz). At temperatures above 100 K, the magnetic resonance linewidth increases linearly with temperature and shows a Gilbert-like linear frequen...
1703.09444v2
2017-03-31
Spin Seebeck effect in Y-type hexagonal ferrite thin films
Spin Seebeck effect (SSE) has been investigated in thin films of two Y-hexagonal ferrites Ba$_2$Zn$_{2}$Fe$_{12}$O$_{22}$ (Zn2Y) and Ba$_2$Co$_{2}$Fe$_{12}$O$_{22}$ (Co2Y) deposited by a spin-coating method on SrTiO$_3$(111) substrate. The selected hexagonal ferrites are both ferrimagnetic with similar magnetic moments...
1703.10903v1
2017-04-05
Superfluid Field response to Edge dislocation motion
We study the dynamic response of a superfluid field to a moving edge dislocation line to which the field is minimally coupled. We use a dissipative Gross-Pitaevskii equation, and determine the initial conditions by solving the equilibrium version of the model. We consider the subsequent time evolution of the field for ...
1704.01600v1
2017-04-29
Multiple steady states and the form of response functions to antigen in a model for the initiation of T cell activation
The aim of this paper is to study the qualitative behaviour predicted by a mathematical model for the initial stage of T cell activation. The state variables in the model are the concentrations of phosphorylation states of the T cell receptor complex and the phosphatase SHP-1 in the cell. It is shown that these quantit...
1705.00149v1
2017-05-12
From an Action Principle for Action-dependent Lagrangians toward non-conservative Gravity: accelerating Universe without dark energy
In the present work, we propose an Action Principle for Action-dependent Lagrangians by generalizing the Herglotz variational problem for several independent variables. This Action Principle enables us to formulate Lagrangian densities for non-conservative fields. In special, from a Lagrangian depending linearly on the...
1705.04604v1
2017-07-21
Temperature dependence of nuclear fission time in heavy-ion fusion-fission reactions
Accounting for viscous damping within Fokker-Planck equations led to various improvements in the understanding and analysis of nuclear fission of heavy nuclei. Analytical expressions for the fission time are typically provided by Kramers' theory, which improves on the Bohr-Wheeler estimate by including the time-scale r...
1707.06836v1
2017-09-18
Stability of traveling, pre-tensioned, heavy cables
We study the dynamics of an inclined tensioned, heavy cable traveling with a constant speed in the vertical plane. The cable is modeled as a beam resisting bending and shear. The governing equation for the transverse in-plane vibrations of the cable are derived through the Newton-Euler method. The cable dynamics is als...
1709.09516v1
2017-10-17
New results on disturbance rejection for energy-shaping controlled port-Hamiltonian systems
In this paper we present a method to robustify energy-shaping controllers for port-Hamiltonian (pH) systems by adding an integral action that rejects unknown additive disturbances. The proposed controller preserves the pH structure and, by adding to the new energy function a suitable cross term between the plant and th...
1710.06070v1
2017-11-15
Probing Split-Ring Resonator Permeabilities with Loop-Gap Resonators
A method is proposed to experimentally determine the effective complex permeability of split-ring resonator (SRR) arrays used in the design of metamaterials at microwave frequencies. We analyze the microwave response of a loop-gap resonator (LGR) whose bore has been partially loaded with one or more SRRs. Our analysis ...
1711.05819v1
2017-11-23
Graphene multi-mode parametric oscillators
In the field of nanomechanics, parametric excitations are of interest since they can greatly enhance sensing capabilities and eliminate cross-talk. However, parametric excitations often rely on externally tuned springs, which limits their application to high quality factor resonators and usually does not allow excitati...
1711.08798v1
2017-12-10
Magnetic field gradient driven dynamics of isolated skyrmions and antiskyrmions in frustrated magnets
The study of skyrmion/antiskyrmion motion in magnetic materials is very important in particular for the spintronics applications. In this work, we study the dynamics of isolated skyrmions and antiskyrmions in frustrated magnets driven by magnetic field gradient, using the Landau-Lifshitz-Gilbert simulations on the frus...
1712.03550v1
2018-01-21
Microwave fields driven domain wall motions in antiferromagnetic nanowires
In this work, we study the microwave field driven antiferromagnetic domain wall motion in an antiferromagnetic nanowire, using the numerical calculations based on a classical Heisenberg spin model. We show that a proper combination of a static magnetic field plus an oscillating field perpendicular to the nanowire axis ...
1801.06748v1
2018-02-07
Breaking the current density threshold in spin-orbit-torque magnetic random access memory
Spin-orbit-torque magnetic random access memory (SOT-MRAM) is a promising technology for the next generation of data storage devices. The main bottleneck of this technology is the high reversal current density threshold. This outstanding problem of SOT-MRAM is now solved by using a current density of constant magnitude...
1802.02415v1
2018-02-20
High-temperature structural phase transition and infrared dielectric features of La2CoMnO6
Temperature-dependent FAR-infrared reflectivity spectra of partially ordered magnetodielectric La2CoMnO6 is presented, from room temperature up to 675 K. A clear first-ordered structural phase transition (SPT) from a monoclinic structure with P2_1/n symmetry to a rhombohedral phase with R-3 symmetry was evidenced from ...
1802.07318v1
2018-03-26
Force spectroscopy analysis in polymer translocation
This paper reports the force spectroscopy analysis of a polymer that translocates from one side of a membrane to the other side through an extended pore, pulled by a cantilever that moves with constant velocity against the damping and the potential barrier generated by the reaction of the membrane walls. The polymer is...
1803.09798v2
2018-03-26
Diffusive stability against nonlocalized perturbations of planar wave trains in reaction-diffusion systems
Planar wave trains are traveling wave solutions whose wave profiles are periodic in one spatial direction and constant in the transverse direction. In this paper, we investigate the stability of planar wave trains in reaction-diffusion systems. We establish nonlinear diffusive stability against perturbations that are b...
1803.09812v2
2018-04-07
Chemotaxis effect vs logistic damping on boundedness in the 2-D minimal Keller-Segel model
In this paper, we study chemotaxis effect vs logistic dampening on boundedness for the two-dimensional minimal Keller-Segel model with logistic source in a 2-D smooth and bounded domain. It is well-known that this model allows only for global and uniform-in-time bounded solutions for any chemotactic strength and logist...
1804.02501v1
2018-04-18
Large perpendicular magnetic anisotropy in epitaxial Fe/MgAl2O4(001) heterostructures
We investigated perpendicular magnetic anisotropy (PMA) and related properties of epitaxial Fe (0.7 nm)/MgAl2O4(001) heterostructures prepared by electron-beam evaporation. Using an optimized structure, we obtained a large PMA energy ~1 MJ/m3 at room temperature, comparable to that in ultrathin-Fe/MgO(001) heterostruct...
1804.06526v2
2018-04-20
Regular solutions to the fractional Euler alignment system in the Besov spaces framework
We here construct (large) local and small global-in-time regular unique solutions to the fractional Euler alignment system in the whole space ${\mathbb R}^d$, in the case where the deviation of the initial density from a constant is sufficiently small. Our analysis strongly relies on the use of Besov spaces of the type...
1804.07611v2
2018-06-01
Dirac-Surface-State Modulated Spin Dynamics in a Ferrimagnetic Insulator at Room Temperature
This work demonstrates dramatically modified spin dynamics of magnetic insulator (MI) by the spin-momentum locked Dirac surface states of the adjacent topological insulator (TI) which can be harnessed for spintronic applications. As the Bi-concentration x is systematically tuned in 5 nm thick (BixSb1-x)2Te3 TI film, th...
1806.00151v1
2018-06-27
Non normal amplification of stochastic quasi-cycles
Stochastic quasi-cycles for a two species model of the excitatory-inhibitory type, arranged on a triangular loop, are studied. By increasing the strength of the inter-nodes coupling, one moves the system towards the Hopf bifurcation and the amplitude of the stochastic oscillations are consequently magnified. When the s...
1806.10566v1
2018-08-15
Collective excitations in two-component one-dimensional massless Dirac plasma
We study spectra of long wavelength plasma oscillations in a system of two energy splitted one-dimensional (1D) massless Dirac fermion subbands coupled by spin-orbit interaction. Such a system may be formed by edge subbands in semiconducting transition metal dichalcogenide monolayers. Intrasubband transitions of massle...
1808.05180v1
2018-09-17
On the speed of domain walls in thin nanotubes: the transition from the linear to the magnonic regime
Numerical simulations of domain wall propagation in thin nanotubes when an external magnetic field is applied along the nanotube axis have shown an unexpected behavior described as a transition from a linear to a magnonic regime. As the applied magnetic field increases, the initial regime of linear growth of the speed ...
1809.06278v3
2018-10-04
Effect of bunch shape on its TMCI spectrum and threshold with high space charge
Transverse mode coupling instability of bunched beam is investigated in the paper at different form of the bunches with space charge included. Equation of transverse motion of the bunch in parabolic potential well of synchrotron oscillations is derived and analysed. The bunch of constant density (flat bunch) is examine...
1810.02458v4
2018-10-11
Stability of scrape-off layer plasma: a modified Rayleigh-Benard problem
We present a linear stability analysis of a two-dimensional fluid model used to study the plasma dynamics in the scrape-off layer of tokamaks. The model equations are based on the Braginskii fluid equations under the assumptions of drift ordering and an electrostatic plasma. The model also employs the common slab geome...
1810.05111v1
2018-10-30
Role of acoustic phonons in exotic conductivity of two-dimensional Dirac electrons
We examine the effect of acoustic phonon scattering on the conductivity of two-dimensional Dirac electrons. The temperature ($T$) dependence of the conductivity ($\sigma$) is calculated using the electron Green's function with damping by both the impurity ($\Gamma_0$) and phonon ($\Gamma_{\rm ph}$).For zero or small do...
1810.12875v1
2018-11-05
Out of Time Ordered Quantum Dissipation
We consider a quantum Brownian particle interacting with two harmonic baths, which is then perturbed by a cubic coupling linking the particle and the baths. This cubic coupling induces non-linear dissipation and noise terms in the influence functional/master equation of the particle. Its effect on the Out-of-Time-Order...
1811.01513v4
2018-12-03
Microscopic theory of magnon-drag electron flow in ferromagnetic metals
A temperature gradient applied to a ferromagnetic metal induces not only independent flows of electrons and magnons but also drag currents because of their mutual interaction. In this paper, we present a microscopic study of the electron flow induced by the drag due to magnons. The analysis is based on the $s$-$d$ mode...
1812.00720v1
2018-12-06
Towards surface diffusion potential mapping on atomic length scale
The surface diffusion potential landscape plays an essential role in a number of physical and chemical processes such as self-assembly and catalysis. Diffusion energy barriers can be calculated theoretically for simple systems, but there is currently no experimental technique to systematically measure them on the relev...
1812.02512v3
2019-01-01
Gravitational Waves in the Presence of Viscosity
We analyze gravitational waves propagating in an isotropic cosmic fluid endowed with a bulk viscosity $\zeta$ and a shear viscosity $\eta$, assuming these coefficients to vary with fluid density $\rho$ as $\rho^\lambda$, with $\lambda=1/2$ favored by experimental evidence. We give the general governing equation for the...
1901.00767v3
2019-01-17
Spin transport parameters of NbN thin films characterised by spin pumping experiments
We present measurements of ferromagnetic-resonance - driven spin pumping and inverse spin-Hall effect in NbN/Y3Fe5O12 (YIG) bilayers. A clear enhancement of the (effective) Gilbert damping constant of the thin-film YIG was observed due to the presence of the NbN spin sink. By varying the NbN thickness and employing spi...
1901.05753v1
2019-04-28
Memory and mutualism in species sustainability: a time-fractional Lotka-Volterra model with harvesting
We first present a predator-prey model for two species and then extend the model to three species where the two predator species engage in mutualistic predation. Constant effort harvesting and the impact of by-catch issue are also incorporated. Necessary sufficient conditions for the existence and stability of positive...
1904.12340v3
2019-05-29
Prospects of reinforcement learning for the simultaneous damping of many mechanical modes
We apply adaptive feedback for the partial refrigeration of a mechanical resonator, i.e. with the aim to simultaneously cool the classical thermal motion of more than one vibrational degree of freedom. The feedback is obtained from a neural network parametrized policy trained via a reinforcement learning strategy to ch...
1905.12344v2
2019-06-10
An automatic dynamic balancer in a rotating mechanism with time-varying angular velocity
We consider the system of a two ball automatic dynamic balancer attached to a rotating disc with nonconstant angular velocity. We directly compare the scenario of constant angular velocity with that when the acceleration of the rotor is taken into consideration. In doing so we show that there are cases where one must t...
1906.04823v1
2019-06-13
Magnetoelasticity of $\mathrm{Co_{25}}\mathrm{Fe_{75}}$ thin films
We investigate the magnetoelastic properties of $\mathrm{Co_{25}}\mathrm{Fe_{75}}$ and $\mathrm{Co_{10}}\mathrm{Fe_{90}}$ thin films by measuring the mechanical properties of a doubly clamped string resonator covered with multi-layer stacks containing these films. For the magnetostrictive constants we find $\lambda_{\m...
1906.05543v1
2019-07-25
Model-independent constraints on the hydrogen-ionizing emissivity at z>6
Modelling reionization often requires significant assumptions about the properties of ionizing sources. Here, we infer the total output of hydrogen-ionizing photons (the ionizing emissivity, $\dot{N}_\textrm{ion}$) at $z=4-14$ from current reionization constraints, being maximally agnostic to the properties of ionizing...
1907.11332v1
2019-09-10
Viscoelasticity-induced pulsatile motion of 2D roll cell in laminar wall-bounded shear flow
For the clarification of the routes to elasto-inertial turbulence (EIT), it is essential to understand how viscoelasticity modulates coherent flow structures including the longitudinal vortices. We focused on a rotating plane Couette flow that provides two-dimensional (2D) roll cells for the steady laminar Newtonian-fl...
1909.04257v1
2019-09-16
On spatial Gevrey regularity for some strongly dissipative second order evolution equations
Let A be a positive self-adjoint linear operator acting on a real Hilbert space H and $\alpha$, c be positive constants. We show that all solutions of the evolution equation u + Au + cA $\alpha$ u = 0 with u(0) $\in$ D(A 1 2), u (0) $\in$ H belong for all t > 0 to the Gevrey space G(A, $\sigma$) with $\sigma$ = min{ 1 ...
1909.07067v1
2019-12-05
Optomechanical cavity without a Stokes side-band
We investigate a theoretical demonstration of perfect frequency conversion in an optomechanical system in the weak coupling regime without a Stokes side-band. An optomechanical cavity illuminated by a weak probe field generates two side-modes, differentiating from the original signal by a phonon frequency. We report th...
1912.02530v1
2019-12-11
Uncertainty Principles Associated to Sets Satisfying the Geometric Control Condition
In this paper, we study forms of the uncertainty principle suggested by problems in control theory. We obtain a version of the classical Paneah-Logvinenko-Sereda theorem for the annulus. More precisely, we show that a function with spectrum in an annulus of a given thickness can be bounded, in $L^2$-norm, from above by...
1912.05077v3
2020-01-04
Observation of spin-motive force in ferrimagnetic GdFeCo alloy films
Non-uniform magnetic structures produce emergent electromagnetic phenomena such as the topological Hall effect and the spin-motive force (SMF). The experimental reports on the SMF, however, are very few and the relationship between the SMF and material parameters is still unclear. In this study, we investigated the SMF...
2001.01042v2
2020-01-06
Suppression of Oscillations in Two-Class Traffic by Full-State Feedback
This paper develops a full-state feedback controller that damps out oscillations in traffic density and traffic velocity whose dynamical behavior is governed by the linearized two-class Aw-Rascle (AR) model. Thereby, the traffic is considered to be in the congested regime and subdivided in two classes whereas each clas...
2001.01504v1
2020-03-26
Bipolar spin Hall nano-oscillators
We demonstrate a novel type of spin Hall nano-oscillator (SHNO) that allows for efficient tuning of magnetic auto-oscillations over an extended range of gigahertz frequencies, using bipolar direct currents at constant magnetic fields. This is achieved by stacking two distinct ferromagnetic layers with a platinum interl...
2003.11776v1
2020-04-01
Quasinormal modes of the Dirac field in the novel 4D Einstein-Gauss-Bonnet gravity
While quasinormal modes of bosonic fields for the non-trivial $4$-dimensional Einstein-Gauss-Bonnet theory of gravity suggested in [D.~Glavan and C.~Lin, Phys.\ Rev.\ Lett.\ {\bf 124}, 081301 (2020)] have been recently studied, there is no such study for fermionic fields. Here we calculate quasinormal modes of the Dira...
2004.00513v2
2020-04-10
Dirichlet boundary valued problems for linear and nonlinear wave equations on arbitrary and fractal domains
The weak well-posedness results of the strongly damped linear wave equation and of the non linear Westervelt equation with homogeneous Dirichlet boundary conditions are proved on arbitrary three dimensional domains or any two dimensional domains which can be obtained by a limit of NTA domains caractarized by the same g...
2004.05055v1
2020-05-09
Self-consistent T-matrix approach to gap renormalization in quantum magnets with bond disorder
Based on the self-consistent T-matrix approximation (SCTMA), analytical theory of density of states (DOS) in three-dimensional quantum magnets with the bond disorder is proposed. It successfully describes DOS in both cases of resonant and non-resonant scattering which appearance is governed by the ratio of scattering l...
2005.04438v2