The dynamics of magnetic vortices and skyrmions

2017 ◽  
Author(s):  
R. Antos ◽  
Y. Otani
Keyword(s):  
Dynamic Properties ◽  
Basic Research ◽  
Small Region ◽  
Magnetic Vortex ◽  
Magnetic Domains ◽  
Spin Configuration ◽  
Magnetic Vortices ◽  
Wall Structures ◽  
Magnetic Elements ◽  
Out Of Plane

This chapter argues that control of magnetic domains and domain wall structures is one of the most important issues from the viewpoint of both applied and basic research in magnetism. Its discussion is however limited to static and dynamic properties of magnetic vortex structures. It has been revealed both theoretically and experimentally that for particular ranges of dimensions of cylindrical and other magnetic elements, a curling in-plane spin configuration is energetically favored, with a small region of the out-of-plane magnetization appearing at the core of the vortex. Such a system, which is sometimes referred to as a magnetic soliton, is characterized by two binary properties: A chirality and a polarity, each of which suggests an independent bit of information in future high-density nonvolatile recording media.

Spin-transfer torque in nonuniform magnetic structures

2017 ◽  
Author(s):  
T. Ono
Keyword(s):  
Magnetic Moments ◽  
Magnetic Domain ◽  
Dipole Interaction ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Magnetic Vortex ◽  
Magnetic Domains ◽  
Spin Configuration ◽  
Magnetic Structures ◽  
Ferromagnetic Disk

This chapter defines a magnetic domain wall (DW) as the transition region where the direction of magnetic moments gradually change between two neighbouring domains. It has been pointed out that ferromagnetic materials are not necessarily magnetized to saturation in the absence of an external magnetic field. Instead, they have magnetic domains, within each of which magnetic moments align. The formation of the magnetic domains is energetically favourable because this structure can lower the magnetostatic energy originating from the dipole–dipole interaction. A magnetic vortex realized in a ferromagnetic disk is a typical example of nonuniform magnetic structure. In very small ferromagnetic systems, where a curling spin configuration has been proposed to occur in place of domains, the formation of DWs is not energetically favored.

scholarly journals Classical magnetic vortex liquid and large thermal Hall conductivity in frustrated magnets with bond-dependent interactions

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Li Ern Chern ◽  
Finn Lasse Buessen ◽  
Yong Baek Kim
Keyword(s):  
Liquid State ◽  
Magnetic Order ◽  
Hall Conductivity ◽  
Magnetic Vortex ◽  
Spin Excitation ◽  
Frustrated Magnets ◽  
Magnetic Vortices ◽  
Vortex Liquid ◽  
Out Of Plane ◽  
Inhomogeneous Spin

AbstractRecently, the observation of large thermal Hall conductivities in correlated insulators with no apparent broken symmetry has generated immense interest and debates on the underlying ground states. Here, considering frustrated magnets with bond-dependent interactions, which are realized in the so-called Kitaev materials, we theoretically demonstrate that a large thermal Hall conductivity can originate from a classical ground state without any magnetic order. We discover a liquid state of magnetic vortices, which are inhomogeneous spin textures embedded in the background of polarized spins, under out-of-plane magnetic fields. In the classical regime, different configurations of vortices form an effectively degenerate manifold. We study the static and dynamical properties of the magnetic vortex liquid state at zero and finite temperatures. In particular, we show that the spin excitation spectrum resembles a continuum of nearly flat Chern bands, which ultimately leads to a large thermal Hall conductivity. Possible connections to experiments are discussed.

QUANTUM MAGNETIC VORTICES AT FINITE TEMPERATURE IN (3 + 1)-D

2000 ◽  
Vol 15 (11n12) ◽  
pp. 731-735
Author(s):  
E. C. MARINO ◽  
D. G. G. SASAKI
Keyword(s):  
Correlation Function ◽  
Correlation Functions ◽  
Large Distance ◽  
Finite Temperature ◽  
Higgs Model ◽  
Magnetic Vortex ◽  
Zero Temperature ◽  
Magnetic Vortices ◽  
Vortex Lines ◽  
Distance Behavior

We study the effect of a finite temperature on the correlation function of quantum magnetic vortex lines in the framework of the (3 + 1)-dimensional Abelian Higgs model. The vortex energy is inferred from the large distance behavior of these correlation functions. For large straight vortices of length L, we obtain that the energy is proportional to TL2 differently from the zero temperature result which is proportional to L. The case of closed strings is also analyzed. For T = 0, we evaluate the correlation function and energy of a large ring. Finite closed vortices do not exist as genuine excitations for any temperature.

Dynamics and Traffic for Transfecting Exogenous MicroRNA as Studied by Live-Cell Microscopy

2021 ◽  
Vol 17 (8) ◽  
pp. 1647-1653
Author(s):  
Ke Yang ◽  
Yuanyuan Wang ◽  
Bo Sun ◽  
Tian Tian ◽  
Zhu Dai ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Mean Square Displacement ◽  
Small Region ◽  
Single Particle Tracking ◽  
Live Cell ◽  
Calculation Results ◽  
Long Time ◽  
Live Cell Microscopy ◽  
Cell Microscopy

MicroRNA (miRNA) has emerged as an important gene-regulator that shows great potential in gene therapy because of its unique roles in gene-regulation. However, the knowledge on their function and transportation in vivo is still lacking, and there are limited obvious evidences to define intracellular transportation of miRNA. In this study, the dynamics of exogenous miR-21 transfected into HeLa cells was traced by live-cell microscopy. Their transportation at key time points was recorded and dynamic properties were analyzed by single particle tracking (SPT) and mean square displacement (MSD) calculation. Results showed that the exogenous miRNAs bounded to cells quickly and went through lysosome into cytosol, where they were subsequently recruited into p-body. They finally were degraded, otherwise went back to cytosol in some way. Long time observation and analysis of motion mode showed that the miRNAs were confined in a small region and their motion modes were flexible in different intracellular microenvironment after entering the cells.

Dynamic Characteristics of Tsing Ma Suspension Bridge

1996 ◽  
Vol 1541 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Siu Kui Au ◽  
Neil Mickleborough ◽  
Paul N. Roschke
Keyword(s):  
Analytical Solutions ◽  
Bridge Deck ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Suspension Bridge ◽  
Mode Shapes ◽  
Out Of Plane ◽  
Quantitative Results ◽  
Suspension Cable ◽  
Bending Modes

Numerical simulation was carried out to determine the dynamic properties of the Tsing Ma Suspension Bridge. Both the structure as a whole and individual subcomponents were modeled. Classical analytical solutions for simplified models from the available literature were compared with the results obtained from a finite-element code. Quantitative results for static deflection, natural frequencies, and mode shapes were compared with analytical solutions from linear theory. Out-of-plane modes were shown to be dominant. For in-plane antisymmetric and symmetric bending modes, in which the suspension cable and bridge deck vibrate in the same direction, the natural frequency of the main span of the bridge is determined to be approximately equal to the square root of the sum of the squares of the frequencies of the cable and bridge deck.

Quantitative investigation of magnetic domains with in-plane and out-of-plane easy axes in GaMnAs films by Hall effect

2013 ◽  
Vol 113 (17) ◽  
pp. 17C706 ◽  
Author(s):  
Sangyeop Lee ◽  
Hakjoon Lee ◽  
Taehee Yoo ◽  
Sanghoon Lee ◽  
X. Liu ◽  
...  
Keyword(s):  
Hall Effect ◽  
Magnetic Domains ◽  
Quantitative Investigation ◽  
Out Of Plane

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.

Stability of Larger Ferromagnetic Chain-of-sphere Nanostructure Comprising Magnetic Vortices

2008 ◽  
Vol 1071 ◽  
Author(s):  
Prabeer Barpanda
Keyword(s):  
Magnetic Properties ◽  
Micromagnetic Simulation ◽  
Magnetic Vortex ◽  
Inversion Symmetry ◽  
Uniform Size ◽  
Magnetic Vortices ◽  
Large Size ◽  
Reversal Process ◽  
Ferromagnetic Chain ◽  
Magnetization Reversal Process

AbstractChain-of-sphere (CoS) nanostructure containing Permalloy (Fe20Ni80) nanospheres of uniform size (d=50 nm) has been studied using micromagnetic simulation. These large-size Permalloy nanospheres support magnetic vortex structure upon relaxation. The presence of magnetic vortices in CoS architecture affects its magnetic properties significantly. Micromagnetic behaviour of Permalloy CoS system was studied focusing on the magnetization reversal process. The presence of magnetic vortices triggers a vortex creation and annihilation mechanism (VCA) involving the formation and breaking of an inversion symmetry (IS) feature. This VCA mechanism has been studied using 3D micromagnetic simulation and results of coercivity and vortex parameters are presented.

scholarly journals Calculation of the Thermal Dynamic Performance of the Residential Buildings’ Walls

2019 ◽  
Vol 1 (1) ◽  
pp. 212-221
Author(s):  
Saša M. Kalinović ◽  
Jelena M. Djoković ◽  
Ružica R. Nikolić ◽  
Branislav Hadzima
Keyword(s):  
Dynamic Properties ◽  
Residential Buildings ◽  
Dynamic Performance ◽  
Thermal Characteristics ◽  
Optimal Solution ◽  
Wall Structure ◽  
Efficiency Ratio ◽  
Heating And Cooling ◽  
Wall Structures ◽  
The Individual

Abstract Calculation of the thermal dynamic properties of the multi-layer wall isolation of residential buildings is presented in this paper. Taking into account that the final objective is to create a building with the highest energy efficiency ratio, i.e. with the lowest energy consumption, both for heating and cooling, it is necessary to realize the good thermal characteristics of the multi-layer wall. To obtain the optimal solution for the wall's structure, various wall structures with different thicknesses of the individual layers, were analyzed. Based on results, presented in this paper, one can conclude that for walls with the same total thickness, but various thicknesses of the individual layers, that constitute the complete wall structure, the differences appear in the delay of the change of the walls outside temperature. In that way, by varying those individual layers' thicknesses, one can obtain the optimal solution for the wall structure with the highest savings of energy.

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