scholarly journals Walker-like domain wall breakdown in layered antiferromagnets driven by staggered spin–orbit fields

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Rubén M. Otxoa ◽  
P. E. Roy ◽  
R. Rama-Eiroa ◽  
J. Godinho ◽  
K. Y. Guslienko ◽  
...  
Keyword(s):  
Domain Wall ◽  
Large Scale ◽  
Domain Walls ◽  
Spin Dynamics ◽  
Continuum Theory ◽  
Dynamical Regime ◽  
Spin Orbit ◽  
Translational Invariance ◽  
Domain Structures ◽  
Dynamics Simulations

Abstract Within linear continuum theory, no magnetic texture can propagate faster than the maximum group velocity of the spin waves. Here, by atomistic spin dynamics simulations and supported by analytical theory, we report that a strongly non-linear transient regime due to the appearance of additional magnetic textures results in the breaking of the Lorentz translational invariance. This dynamical regime is akin to domain wall Walker-breakdown in ferromagnets and involves the nucleation of an antiferromagnetic domain wall pair. While one of the nucleated domain walls is accelerated beyond the magnonic limit, the remaining pair remains static. Under large spin–orbit fields, a cascade of multiple generation and recombination of domain walls are obtained. This result may clarify recent experiments on current pulse induced shattering of large domain structures into small fragmented domains and the subsequent slow recreation of large-scale domains.

scholarly journals Discovery and characterization of a new type of domain wall in a row-wise antiferromagnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jonas Spethmann ◽  
Martin Grünebohm ◽  
Roland Wiesendanger ◽  
Kirsten von Bergmann ◽  
André Kubetzka
Keyword(s):  
Domain Wall ◽  
Spin Structure ◽  
Domain Walls ◽  
Spin Dynamics ◽  
Magnetic Interactions ◽  
Theoretical Modelling ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
New Type ◽  
Dynamics Simulations

AbstractAntiferromagnets have recently moved into the focus of application-related research, with the perspective to use them in future spintronics devices. At the same time the experimental determination of the detailed spin texture remains challenging. Here we use spin-polarized scanning tunneling microscopy to investigate the spin structure of antiferromagnetic domain walls. Comparison with spin dynamics simulations allows the identification of a new type of domain wall, which is a superposition state of the adjacent domains. We determine the relevant magnetic interactions and derive analytical formulas. Our experiments show a pathway to control the number of domain walls by boundary effects, and demonstrate the possibility to change the position of domain walls by interaction with movable adsorbed atoms. The knowledge about the exact spin structure of the domain walls is crucial for an understanding and theoretical modelling of their properties regarding, for instance, dynamics, response in transport experiments, and manipulation.

The need of electron microscopy in the study of domains and domain walls in ferroelectrics

1994 ◽  
Vol 52 ◽  
pp. 550-551
Author(s):  
Wenwu Cao
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
High Mobility ◽  
Continuum Theory ◽  
Polarization Vector ◽  
Ferroelectric Materials ◽  
Dielectric Constants ◽  
Nonlocal Coupling ◽  
Cubic Symmetry ◽  
Gradient Energy

Domain structures play a key role in determining the physical properties of ferroelectric materials. The formation of these ferroelectric domains and domain walls are determined by the intrinsic nonlinearity and the nonlocal coupling of the polarization. Analogous to soliton excitations, domain walls can have high mobility when the domain wall energy is high. The domain wall can be describes by a continuum theory owning to the long range nature of the dipole-dipole interactions in ferroelectrics. The simplest form for the Landau energy is the so called ϕ model which can be used to describe a second order phase transition from a cubic prototype,where Pi (i =1, 2, 3) are the components of polarization vector, α's are the linear and nonlinear dielectric constants. In order to take into account the nonlocal coupling, a gradient energy should be included, for cubic symmetry the gradient energy is given by,

scholarly journals Periodic Boundary Conditions for Dislocation Dynamics Simulations in Three Dimensions

2000 ◽  
Vol 653 ◽  
Author(s):  
Vasily V. Bulatov ◽  
Moon Rhee ◽  
Wei Cai
Keyword(s):  
Boundary Conditions ◽  
Large Scale ◽  
Periodic Boundary ◽  
Periodic Boundary Conditions ◽  
Dislocation Dynamics ◽  
Three Dimensions ◽  
Translational Invariance ◽  
Timing Data ◽  
Dynamics Simulations ◽  
Consistent Treatment

AbstractThis article presents an implementation of periodic boundary conditions (PBC) for Dislocation Dynamics (DD) simulations in three dimensions (3D). We discuss fundamental aspects of PBC development, including preservation of translational invariance and line connectivity, the choice of initial configurations compatible with PBC and a consistent treatment of image stress. On the practical side, our approach reduces to manageable proportions the computational burden of updating the long-range elastic interactions among dislocation segments. The timing data confirms feasibility and practicality of PBC for large-scale DD simulations in 3D.

scholarly journals The decay of the refocused Hahn echo in DEER experiments

2021 ◽  
Author(s):  
Thorsten Bahrenberg ◽  
Samuel M. Jahn ◽  
Akiva Feintuch ◽  
Stefan Stoll ◽  
Daniella Goldfarb
Keyword(s):  
Electron Spin ◽  
Large Scale ◽  
Pulse Sequence ◽  
Spin Dynamics ◽  
Spin Echo ◽  
Sequence Length ◽  
Paramagnetic Resonance ◽  
Flip Flop ◽  
Spin Dephasing ◽  
Dynamics Simulations

Abstract. Double electron–electron resonance (DEER) is a pulse electron paramagnetic resonance (EPR) technique that measures distances between paramagnetic centres. It utilizes a four-pulse sequence based on the refocused Hahn spin echo. The echo decays with increasing pulse sequence length 2(τ1 + τ2), where τ1 and τ2 are the two time delays. In DEER, the value of τ2 is determined by the longest inter-spin distance that needs to be resolved, and τ1 is adjusted to maximize the echo amplitude and thus sensitivity. We show experimentally that for typical spin centres (nitroxyl, trityl, Gd(III)) diluted in frozen protonated solvents, the largest refocused echo amplitude for a given τ2 is obtained neither at very short τ1 (which minimizes the pulse sequence length) nor at τ1 = τ2 (which maximizes dynamic decoupling for a given total sequence length), but rather at τ1 values smaller than τ2. Large-scale spin dynamics simulations including the electron spin and several hundred neighbouring protons reproduce the experimentally observed behaviour almost quantitatively. They show that electron spin dephasing is driven by solvent protons via the flip-flop coupling among themselves and their hyperfine couplings to the electron spin.

DYNAMICS OF FERROMAGNETIC WALLS: GRAVITATIONAL PROPERTIES

2005 ◽  
Vol 14 (03n04) ◽  
pp. 521-541 ◽  
Author(s):  
L. CAMPANELLI ◽  
P. CEA ◽  
G. L. FOGLI ◽  
L. TEDESCO
Keyword(s):  
Domain Wall ◽  
Large Scale ◽  
Domain Walls ◽  
Background Radiation ◽  
Ideal Gas ◽  
Microwave Background ◽  
Electroweak Phase Transition ◽  
Microwave Background Radiation ◽  
The Universe ◽  
Negligible Contribution

We discuss a new mechanism which allows domain walls produced during the primordial electroweak phase transition. We show that the effective surface tension of these domain walls can be made vanishingly small due to a peculiar magnetic condensation induced by fermion zero modes localized on the wall. We find that in the perfect gas approximation the domain wall network behaves like a radiation gas. We consider the recent high-red shift supernova data and we find that the corresponding Hubble diagram is compatible with the presence in the Universe of an ideal gas of ferromagnetic domain walls. We show that our domain wall gas induces a completely negligible contribution to the large-scale anisotropy of the microwave background radiation.

scholarly journals Interconversion of multiferroic domains and domain walls

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
E. Hassanpour ◽  
M. C. Weber ◽  
Y. Zemp ◽  
L. Kuerten ◽  
A. Bortis ◽  
...  
Keyword(s):  
Domain Wall ◽  
Physical Properties ◽  
Domain Walls ◽  
Three Dimensional ◽  
Topological Defects ◽  
Long Range Order ◽  
Two Dimensional ◽  
Domain Structures ◽  
Topological Singularities ◽  
Ordered State

AbstractSystems with long-range order like ferromagnetism or ferroelectricity exhibit uniform, yet differently oriented three-dimensional regions called domains that are separated by two-dimensional topological defects termed domain walls. A change of the ordered state across a domain wall can lead to local non-bulk physical properties such as enhanced conductance or the promotion of unusual phases. Although highly desirable, controlled transfer of these properties between the bulk and the spatially confined walls is usually not possible. Here, we demonstrate this crossover by confining multiferroic Dy0.7Tb0.3FeO3 domains into multiferroic domain walls at an identified location within a non-multiferroic environment. This process is fully reversible; an applied magnetic or electric field controls the transformation. Aside from expanding the concept of multiferroic order, such interconversion can be key to addressing antiferromagnetic domain structures and topological singularities.

scholarly journals Effects of Rashba Spin-Orbit Coupling On the Anisotropic Magneto Resistance in Domain Wall -=SUP=-*-=/SUP=-

2018 ◽  
Vol 60 (7) ◽  
pp. 1321
Author(s):  
J. Azizi
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
Orbit Interaction ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Electron Current ◽  
Rashba Spin ◽  
Magneto Resistance ◽  
Rashba Coupling ◽  
Classical Boltzmann Equation

AbstractThe present paper, based on semi-classical Boltzmann equation, aims to investigate the effects of Rashba and Dresselhaus spin orbit interaction and impurities on domain wall anisotropic magneto resistance. It has been shown that the mentioned effects play a remarkable role in anisotropic magneto resistance of electron current in domain walls. It was also concluded that while an increase in Rashba coupling strength can effectively enhance anisotropic magneto resistance of the domain wall, an increase in the wave-vector and exchange interaction leads to their decrease.

scholarly journals Measurement of the tilt of a moving domain wall shows precession-free dynamics in compensated ferrimagnets

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
E. Haltz ◽  
J. Sampaio ◽  
S. Krishnia ◽  
L. Berges ◽  
R. Weil ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Domain Wall ◽  
Low Power ◽  
High Speed ◽  
Domain Walls ◽  
Spin Orbit ◽  
Spin Lattices ◽  
Moving Domain ◽  
Moving Domain Wall

Abstract One fundamental obstacle to efficient ferromagnetic spintronics is magnetic precession, which intrinsically limits the dynamics of magnetic textures. We experimentally demonstrate that this precession vanishes when the net angular momentum is compensated in domain walls driven by spin–orbit torque in a ferrimagnetic GdFeCo/Pt track. We use transverse in-plane fields to provide a robust and parameter-free measurement of the domain wall internal magnetisation angle, demonstrating that, at the angular compensation, the DW tilt is zero, and thus the magnetic precession that caused it is suppressed. Our results highlight the mechanism of faster and more efficient dynamics in materials with multiple spin lattices and vanishing net angular momentum, promising for high-speed, low-power spintronic applications.

Nonlinear theory of modulated standing waves; domain walls, kinks and breathers

1993 ◽  
Vol 440 (1908) ◽  
pp. 135-148 ◽  
Keyword(s):  
Domain Wall ◽  
Nonlinear Theory ◽  
Toda Lattice ◽  
Domain Walls ◽  
Standing Waves ◽  
Wave Number ◽  
One Dimension ◽  
Spontaneous Breaking ◽  
Translational Invariance ◽  
Localized Solutions

A nonlinear theory of modulated standing waves is developed in one dimension. The existence of various localized solutions is elucidated. These include: domain walls , which characterize the transition between regions of different wave number, kinks , which describe a shift in the phase of the oscillation, and lower cut-off breathers . All of these states correspond to a spontaneous breaking of translational invariance, while the domain wall in addition represents a broken parity. Except for the breathers, the modulational equations that describe these states take a form that differs from the sine-Gordon, nonlinear Schrödinger, Toda lattice and Korteweg de Vries equations. In addition to the hamiltonian limit, the case of damped parametrically driven motion is also discussed.

Imaging of Ferroelectric Domains in KTiOPO4 Single Crystals by Synchrotron X-RAY Topography

1993 ◽  
Vol 310 ◽  
Author(s):  
S. Wang ◽  
M. Dudley ◽  
L.K. Cheng ◽  
J.D. Bierlein ◽  
W. Bindloss
Keyword(s):  
Domain Wall ◽  
Single Crystals ◽  
Long Range ◽  
Domain Walls ◽  
Three Dimensional ◽  
Dynamical Theory ◽  
X Ray Diffraction ◽  
X Ray ◽  
Domain Structures ◽  
Main Components

AbstractThe application of synchrotron white beam X-ray topography to the study of ferroelectric domain structures in hydrothermally grown potassium titanyl phosphate (KTiOPO4: KTP) single crystals is reported. The domain walls can be exclusively imaged on topographs with selected diffraction vectors and X-ray wavelengths, while images of other defects, such as dislocations, inclusions and surface scratches, can be simultaneously made very diffuse. The topographic images correspond well with electrostatic toning images. X-ray topography readily reveals the three dimensional shapes of the domain walls. There are two contributions to domain wall contrast: one is fringe-like which can be interpreted in terms of the dynamical theory of X-ray diffraction, and the other is diffuse strain contrast arising from long range strain associated with the wall. These two contributions can be observed simultaneously or separately depending on the diffraction conditions. The long range strain is thought to be associated with the curvature of the domain walls. It appears that the main components of the displacement field associated with this strain are directed approximately perpendicular to the domain wall.

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