scholarly journals Current vortices and magnetic fields driven by moving polar twin boundaries in ferroelastic materials

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Guangming Lu ◽  
Suzhi Li ◽  
Xiangdong Ding ◽  
Jun Sun ◽  
Ekhard K. H. Salje
Keyword(s):  
Magnetic Fields ◽  
Speed Of Sound ◽  
Magnetic Moment ◽  
Domain Walls ◽  
Domain Boundary ◽  
Polar Vortex ◽  
Magnetic Memory ◽  
Magnetic Element ◽  
Twin Boundaries ◽  
Moving Domain

Abstract Ferroelastic twin boundaries often have properties that do not exist in bulk, such as superconductivity, polarity etc. Designing and optimizing domain walls can hence functionalize ferroelastic materials. Using atomistic simulations, we report that moving domain walls have magnetic properties even when there is no magnetic element in the material. The origin of a robust magnetic signal lies in polar vortex structures induced by moving domain walls, e.g., near the tips of needle domains and near domain wall kinks. These vortices generate displacement currents, which are the origin of magnetic moments perpendicular to the vortex plane. This phenomenon is universal for ionic crystals and holds for all ferroelastic domain boundaries containing dipolar moments. The magnetic moment depends on the speed of the domain boundary, which can reach the speed of sound under strong mechanical forcing. We estimate that the magnetic moment can reach several tens of Bohr magnetons for a collective thin film of 1000 lattice planes and movements of the vortex by the speed of sound. The predicted magnetic fields in thin slabs are much larger than those observed experimentally in SrTiO3/LaAlO3 heterostructures, which may be due to weak (accidental) forcing and slow changes of the domain patterns during their experiments. The dynamical multiferroic properties of ferroelastic domain walls may have the potential to be used to construct localized magnetic memory devices in future.

Interaction of moving domain walls with constant magnetic fields in iron borate and yttrium orthoferrite single crystals

2016 ◽  
Author(s):  
Evgenij A. Zhukov ◽  
Maria E. Adamova ◽  
Olga Yu. Komina ◽  
Aleksandr V. Kaminsky ◽  
Valentina I. Zhukova
Keyword(s):  
Magnetic Fields ◽  
Single Crystals ◽  
Domain Walls ◽  
Iron Borate ◽  
Yttrium Orthoferrite ◽  
Moving Domain

scholarly journals Magnetic memory and current amplification devices using moving domain walls

2006 ◽  
Vol 89 (12) ◽  
pp. 122507 ◽  
Author(s):  
S. E. Barnes ◽  
J. Ieda ◽  
S. Maekawa
Keyword(s):  
Domain Walls ◽  
Magnetic Memory ◽  
Moving Domain ◽  
Current Amplification

Introduction to Domain Boundary Engineering

Domain Walls ◽  
2020 ◽  
pp. 109-128
Author(s):  
E. K. H. Salje ◽  
G. Lu
Keyword(s):  
Domain Walls ◽  
Bulk Material ◽  
Domain Boundary ◽  
Functional Domain ◽  
The Novel ◽  
Antiphase Boundaries ◽  
Twin Boundaries ◽  
Domain Boundaries ◽  
Device Applications ◽  
Bloch Lines

This chapter introduces research on functional domain boundaries. Ever since the discovery of superconducting twin boundaries in the 1990s, highly conducting, polar, photovoltaic, magnetic, and so on, domain boundaries have been discovered while the same bulk material displays none of these properties. Domain boundaries constitute planar templates for device applications with thicknesses of ca. 1 nm. Domains within domains are then the next step in miniaturization with Bloch lines within domain walls and Bloch points between Bloch lines. In the overwhelming majority of cases, the geometrical template for the functional domain boundaries stems from the ferroelastic domain structure, while antiphase boundaries are equally potential template providers. Complex structures are a particular case because they add vortices and skyrmions to the template topology. Correlations between such sub-structures maintain features like polarity and piezoelectricity in randomized samples where structural averages would not allow macroscopic polar effects. The dynamics of the change of functionality is often much faster than the speed with which twin boundaries move. The novel information carrier is the kink inside twin walls, which moves with supersonic speed.

scholarly journals Giant conductivity of mobile non-oxide domain walls

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. Ghara ◽  
K. Geirhos ◽  
L. Kuerten ◽  
P. Lunkenheimer ◽  
V. Tsurkan ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Domain Wall ◽  
Domain Walls ◽  
Building Blocks ◽  
External Fields ◽  
Tail Domain ◽  
Oxide Electronics ◽  
Domain Wall Mobility ◽  
Conductance Changes ◽  
Wall Mobility

AbstractAtomically sharp domain walls in ferroelectrics are considered as an ideal platform to realize easy-to-reconfigure nanoelectronic building blocks, created, manipulated and erased by external fields. However, conductive domain walls have been exclusively observed in oxides, where domain wall mobility and conductivity is largely influenced by stoichiometry and defects. Here, we report on giant conductivity of domain walls in the non-oxide ferroelectric GaV4S8. We observe conductive domain walls forming in zig-zagging structures, that are composed of head-to-head and tail-to-tail domain wall segments alternating on the nanoscale. Remarkably, both types of segments possess high conductivity, unimaginable in oxide ferroelectrics. These effectively 2D domain walls, dominating the 3D conductance, can be mobilized by magnetic fields, triggering abrupt conductance changes as large as eight orders of magnitude. These unique properties demonstrate that non-oxide ferroelectrics can be the source of novel phenomena beyond the realm of oxide electronics.

scholarly journals Persistent magnetic vortex flow at a supergranular vertex

2018 ◽  
Vol 610 ◽  
pp. A84 ◽  
Author(s):  
Iker S. Requerey ◽  
Basilio Ruiz Cobo ◽  
Milan Gošić ◽  
Luis R. Bellot Rubio
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Vortex Flow ◽  
Spatial Scales ◽  
Magnetic Vortex ◽  
Magnetic Feature ◽  
Magnetic Element ◽  
Flow Maps ◽  
Wide Range ◽  
Intensity Images

Context. Photospheric vortex flows are thought to play a key role in the evolution of magnetic fields. Recent studies show that these swirling motions are ubiquitous in the solar surface convection and occur in a wide range of temporal and spatial scales. Their interplay with magnetic fields is poorly characterized, however. Aims. We study the relation between a persistent photospheric vortex flow and the evolution of a network magnetic element at a supergranular vertex. Methods. We used long-duration sequences of continuum intensity images acquired with Hinode and the local correlation-tracking method to derive the horizontal photospheric flows. Supergranular cells are detected as large-scale divergence structures in the flow maps. At their vertices, and cospatial with network magnetic elements, the velocity flows converge on a central point. Results. One of these converging flows is observed as a vortex during the whole 24 h time series. It consists of three consecutive vortices that appear nearly at the same location. At their core, a network magnetic element is also detected. Its evolution is strongly correlated to that of the vortices. The magnetic feature is concentrated and evacuated when it is caught by the vortices and is weakened and fragmented after the whirls disappear. Conclusions. This evolutionary behavior supports the picture presented previously, where a small flux tube becomes stable when it is surrounded by a vortex flow.

Structure of Moving Domain Walls in Magnetic Materials

1971 ◽  
Vol 19 (8) ◽  
pp. 274-276 ◽  
Author(s):  
Ernst Schlömann
Keyword(s):  
Magnetic Materials ◽  
Domain Walls ◽  
Moving Domain

scholarly journals Information storage in permalloy modulated magnetic nanowires

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guidobeth Sáez ◽  
Pablo Díaz ◽  
Eduardo Cisternas ◽  
Eugenio E. Vogel ◽  
Juan Escrig
Keyword(s):  
Magnetic Material ◽  
Phase Diagram ◽  
Magnetic Fields ◽  
Domain Walls ◽  
Wire Diameter ◽  
Information Storage ◽  
Magnetic Nanowires ◽  
The Wire ◽  
The Stability ◽  
Cylindrical Wire

AbstractA long piece of magnetic material shaped as a central cylindrical wire (diameter $$d=50$$ d = 50 nm) with two wider coaxial cylindrical portions (diameter $$D=90$$ D = 90 nm and thickness $$t=100$$ t = 100 nm) defines a bimodulated nanowire. Micromagnetism is invoked to study the equilibrium energy of the system under the variations of the positions of the modulations along the wire. The system can be thought of as composed of five independent elements (3 segments and 2 modulations) leading to $$2^5=32$$ 2 5 = 32 possible different magnetic configurations, which will be later simplified to 4. We investigate the stability of the configurations depending on the positions of the modulations. The relative chirality of the modulations has negligible contributions to the energy and they have no effect on the stability of the stored configuration. However, the modulations are extremely important in pinning the domain walls that lead to consider each segment as independent from the rest. A phase diagram reporting the stability of the inscribed magnetic configurations is produced. The stability of the system was then tested under the action of external magnetic fields and it was found that more than 50 mT are necessary to alter the inscribed information. The main purpose of this paper is to find whether a prototype like this can be complemented to be used as a magnetic key or to store information in the form of firmware. Present results indicate that both possibilities are feasible.

scholarly journals Магнитостатическая энергия доменных стенок в одноосных пленках конечных размеров

2019 ◽  
Vol 61 (10) ◽  
pp. 1767
Author(s):  
П.М. Ветошко ◽  
Ф.П. Ветошко ◽  
В.Г. Шавров ◽  
В.И. Щеглов
Keyword(s):  
Domain Walls ◽  
Magnetic Sensors ◽  
Magnetization Distribution ◽  
Magnetic Memory ◽  
Spintronic Devices ◽  
Domain Structures ◽  
Magnetic Elements ◽  
Uniform Magnetization ◽  
Equilibrium Configurations ◽  
Equivalent Currents

AbstractThe solution to the problem of calculating the magnetostatic interaction energy of domain walls in uniaxial magnetics with a uniform magnetization distribution inside the domains is given. In carrying out the calculations, the principle of equivalent currents is used, assuming a uniform distribution of magnetization and its representation by equivalent currents flowing along the domain walls and along the surface. Analytical expressions for the mutual induction of two rectangular conductors with an arbitrary aspect ratio have been obtained. Results may be helpful in determining equilibrium configurations of domain structures in magnetic elements of spintronic devices, magnetic sensors and magnetic memory.

Driving chiral domain walls in antiferromagnets using rotating magnetic fields

2018 ◽  
Vol 97 (18) ◽  
Author(s):  
Keming Pan ◽  
Lingdi Xing ◽  
H. Y. Yuan ◽  
Weiwei Wang
Keyword(s):  
Magnetic Fields ◽  
Domain Walls ◽  
Rotating Magnetic Fields

scholarly journals Nanoscale strain engineering of giant pseudo-magnetic fields, valley polarization, and topological channels in graphene

2020 ◽  
Vol 6 (19) ◽  
pp. eaat9488 ◽  
Author(s):  
C.-C. Hsu ◽  
M. L. Teague ◽  
J.-Q. Wang ◽  
N.-C. Yeh
Keyword(s):  
Magnetic Fields ◽  
Domain Walls ◽  
Quantum Hall ◽  
Strain Engineering ◽  
Scanning Tunneling ◽  
Monolayer Graphene ◽  
Tunneling Microscopy ◽  
One Dimensional ◽  
Valley Polarization ◽  
Topological States

The existence of nontrivial Berry phases associated with two inequivalent valleys in graphene provides interesting opportunities for investigating the valley-projected topological states. Examples of such studies include observation of anomalous quantum Hall effect in monolayer graphene, demonstration of topological zero modes in “molecular graphene” assembled by scanning tunneling microscopy, and detection of topological valley transport either in graphene superlattices or at bilayer graphene domain walls. However, all aforementioned experiments involved nonscalable approaches of either mechanically exfoliated flakes or atom-by-atom constructions. Here, we report an approach to manipulating the topological states in monolayer graphene via nanoscale strain engineering at room temperature. By placing strain-free monolayer graphene on architected nanostructures to induce global inversion symmetry breaking, we demonstrate the development of giant pseudo-magnetic fields (up to ~800 T), valley polarization, and periodic one-dimensional topological channels for protected propagation of chiral modes in strained graphene, thus paving a pathway toward scalable graphene-based valleytronics.

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