Topological Defects in Nanostructures—Chiral Domain Walls and Skyrmions

2016 ◽  
pp. 199-218 ◽  
Author(s):  
Benjamin Krüger ◽  
Mathias Kläui
Keyword(s):  
Domain Walls ◽  
Topological Defects

scholarly journals QUARKS AS TOPOLOGICAL DEFECTS — OR, WHAT IS CONFINED INSIDE A HADRON?

1993 ◽  
Vol 08 (31) ◽  
pp. 5575-5604 ◽  
Author(s):  
A. KOVNER ◽  
B. ROSENSTEIN
Keyword(s):  
Magnetic Flux ◽  
Topological Charge ◽  
Domain Walls ◽  
Topological Defects ◽  
Complex Scalar ◽  
Yang Mills ◽  
Effective Lagrangian ◽  
Local Complex ◽  
Complex Scalar Field ◽  
The One

We present a picture of confinement based on representation of constituent quarks as pointlike topological defects. The topological charge carried by quarks and confined in hadrons is explicitly constructed in terms of Yang-Mills variables. In 2+1 dimensions we are able to construct a local complex scalar field V(x), in terms of which the topological charge is [Formula: see text]. The VEV of the field V in the confining phase is nonzero and the charge is the winding number corresponding to homotopy group π1(S1). Quarks carry the charge Q and therefore are topological solitons. The phase rotation of V is generated by the operator of magnetic flux. Unlike in QED, the U(1) magnetic flux is explicitly broken by the monopoles. This results in formation of a string between a quark and an antiquark. The effective Lagrangian for V is derived in models with adjoint and fundamental quarks. This topological mechanism of confinement is basically different from the one proposed by ’t Hooft in which the elementary objects are linelike domain walls. A baryon is described as a Y-shaped configuration of strings. In 3+1 dimensions the explicit expression for V, and therefore a detailed picture, is not available. However, assuming the validity of the same mechanism we point out several interesting qualitative consequences.

CHARGED DOMAIN WALLS

2004 ◽  
Vol 13 (01) ◽  
pp. 65-74 ◽  
Author(s):  
L. CAMPANELLI ◽  
P. CEA ◽  
G. L. FOGLI ◽  
L. TEDESCO
Keyword(s):  
Magnetic Field ◽  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Domain Walls ◽  
Topological Defects ◽  
Electric And Magnetic Field

In this paper we investigate Charged Domain Walls (CDW's), topological defects that acquire surface charge density Q induced by fermion states localized on the walls. The presence of an electric and magnetic field on the walls is also discussed. We find a relation in which the value of the surface charge density Q is connected with the existence of such topological defects.

scholarly journals Stiffness in vortex—like structures due to chirality-domains within a coupled helical rare-earth superlattice

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Amitesh Paul
Keyword(s):  
Rare Earth ◽  
Domain Walls ◽  
Topological Defects ◽  
Magnetic Ordering ◽  
Direct Consequence ◽  
Magnetic Vortex ◽  
Range Magnetic Order ◽  
Wide Range ◽  
Out Of Plane ◽  
The Stability

Abstract Vortex domain walls poses chirality or ‘handedness’ which can be exploited to act as memory units by changing their polarity with electric field or driving/manupulating the vortex itself by electric currents in multiferroics. Recently, domain walls formed by one dimensional array of vortex—like structures have been theoretically predicted to exist in disordered rare-earth helical magnets with topological defects. Here, in this report, we have used a combination of two rare-earth metals, e.g."Equation missing" superlattice that leads to long range magnetic order despite their competing anisotropies along the out-of-plane (Er) and in-plane (Tb) directions. Probing the vertically correlated magnetic structures by off-specular polarized neutron scattering we confirm the existence of such magnetic vortex—like domains associated with magnetic helical ordering within the Er layers. The vortex—like structures are predicted to have opposite chirality, side—by—side and are fairly unaffected by the introduction of magnetic ordering between the interfacial Tb layers and also with the increase in magnetic field which is a direct consequence of screening of the vorticity in the system due to a helical background. Overall, the stability of these vortices over a wide range of temperatures, fields and interfacial coupling, opens up the opportunity for fundamental chiral spintronics in unconventional systems.

scholarly journals Polarizability of electrically induced magnetic vortex “atoms”

2018 ◽  
Vol 185 ◽  
pp. 07003
Author(s):  
P.I. Karpov ◽  
S.I. Mukhin
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Domain Walls ◽  
Topological Defects ◽  
Magnetic Vortex ◽  
Distribution Profile ◽  
Magnetic Structures ◽  
Magnetic Vortices ◽  
Vortex Density ◽  
Magnetoelectric Materials

Electric field control of magnetic structures, particularly topological defects in magnetoelectric materials, draws a great attention, which has led to experimental success in creation and manipulation of single magnetic defects, such as skyrmions and domain walls. In this work we explore a scenario of electric field creation of another type of topological defects – magnetic vortices and antivortices. Because of interaction of magnetic and electric subsystems each magnetic vortex (antivortex) in magnetoelectric materials possesses quantized magnetic charge, responsible for interaction between vortices, and electric charge that couples them to electric field. This property of magnetic vortices makes possible their creation by electric fields. We show that the electric field, created by a cantilever tip, produces a “magnetic atom” with a localized spot of ordered vortices (“nucleus” of the atom) surrounded by antivortices (“electronic shells”). We analytically find the vortex density distribution profile and temperature dependence of polarizability of this structure and confirm it numerically by Monte Carlo simulation.

Thermodynamic and statistical properties of charged topological defects

2002 ◽  
Vol 12 (9) ◽  
pp. 235-236
Author(s):  
S. Teber
Keyword(s):  
Domain Walls ◽  
Density Wave ◽  
Topological Defects ◽  
Statistical Properties ◽  
Dimensional System ◽  
Coulomb Interactions ◽  
One Dimensional ◽  
Long Range Interactions ◽  
Component Plasma ◽  
Stripe Phases

We focus on the statistical and thermodynamic properties of systems with competing long-range interactions. The studies are based on the physics of quasi-one dimensional system with special interest towards their topological defects, the so-called solitons. We have been considering ensembles of solitons resulting from the degeneracy of the ground state of the system. This is the case of various charge density-wave systems such as polyacetylene-like polymers where the solitons are the non-trivial excitations connecting different ground-states. We have been interested in particular with a one component plasma with $3D$ Coulomb interactions of such defects, mainly in 2 space dimensions. The $3D$ case has also been considered. The quasi-one dimensional nature of the system is responsible for the confinement of the solitons. This competition between confinement and Coulomb has been formulated and some of its non-trivial effects analyaed. This led us to study the statistical properties of charged interfaces: strings or domain walls in $3D$. We have found that shape instabilities, due to the competing interactions, play a fundamental role. The obtained results show similarities with experimental work in the field of stripe phases in cuprate oxides.

Inhomogeneities in antiferromagnetic solids

2002 ◽  
Vol 12 (9) ◽  
pp. 253-256
Author(s):  
F. V. Kusmartsev
Keyword(s):  
Domain Walls ◽  
Topological Defects ◽  
Coulomb Repulsion ◽  
Elementary Excitations ◽  
Closed Loops ◽  
Size And Shape ◽  
Phase Domain ◽  
Self Organized ◽  
Ferro Magnetic ◽  
New Type

We find that in narrow hand anti-ferro-magnetic (AF) solids described by general t-J model there may arise electronic molecules or clusters consisting of holes. These holes are segregated around the topological defects such as loops of anti-phase domain walls. The loops are naturally self-organized into the closed loops of triangular, square, rectangular or other form depending on physical situations. This kind of electron molecules is spontaneously formed in AF background and constitute a new type of elementary excitations of the AF solids. We find that the size and shape of these e-molecules depend mostly on the AF coupling J and the bandwidth $4t$ as well as on the inter-site Coulomb repulsion between holes.

scholarly journals Nonlocal Quantum Effects in Cosmology

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Yurii V. Dumin
Keyword(s):  
Early Universe ◽  
Large Scale ◽  
Domain Walls ◽  
Early Stage ◽  
Topological Defects ◽  
Anomalous Behavior ◽  
Quantum Nonlocality ◽  
Ultracold Gases ◽  
Laboratory Studies ◽  
Microwave Background

Since it is commonly believed that the observed large-scale structure of the universe is an imprint of quantum fluctuations existing at the very early stage of its evolution, it is reasonable to pose the question: do the effects of quantum nonlocality, which are well established now by the laboratory studies, manifest themselves also in the early universe? We try to answer this question by utilizing the results of a few experiments, namely, with the superconducting multi-Josephson-junction loops and the ultracold gases in periodic potentials. Employing a close analogy between the above-mentioned setups and the simplest one-dimensional Friedmann-Robertson-Walker cosmological model, we show that the specific nonlocal correlations revealed in the laboratory studies might be of considerable importance also in treating the strongly nonequilibrium phase transitions of Higgs fields in the early universe. Particularly, they should substantially reduce the number of topological defects (e.g., domain walls) expected due to independent establishment of the new phases in the remote spatial regions. This gives us a hint on resolving a long-standing problem of the excessive concentration of topological defects, inconsistent with observational constraints. The same effect may be also relevant to the recent problem of the anomalous behavior of cosmic microwave background fluctuations at large angular scales.

scholarly journals KINKS AND DOMAIN WALLS IN MODELS FOR REAL SCALAR FIELDS

2004 ◽  
Vol 19 (04) ◽  
pp. 575-592 ◽  
Author(s):  
D. BAZEIA ◽  
A. S. INÁCIO ◽  
L. LOSANO
Keyword(s):  
High Energy Physics ◽  
Domain Walls ◽  
Topological Defects ◽  
Scalar Fields ◽  
High Energy ◽  
Specific Model ◽  
Real Scalar ◽  
Thermal Investigations ◽  
Spatially Extended ◽  
The One

We investigate several models described by real scalar fields, searching for topological defects, and investigating their linear stability. We also find bosonic zero modes and examine the thermal corrections at the one-loop level. The classical investigations are of direct interest to high energy physics and to applications in condensed matter, in particular to spatially extended systems where fronts and interfaces separating different phase states may appear. The thermal investigations show that the finite temperature corrections that appear in a specific model induce a second-order phase transition in the system, although the thermal effects do not suffice to fully restore the symmetry at high temperature.

Topological defects inside domain walls

1996 ◽  
Vol 54 (2) ◽  
pp. 1852-1855 ◽  
Author(s):  
D. Bazeia ◽  
R. F. Ribeiro ◽  
M. M. Santos
Keyword(s):  
Domain Walls ◽  
Topological Defects
Sign in / Sign up

Export Citation Format

Share Document