scholarly journals Micromagnetic Simulation of Vortex Development in Magnetic Bi-Material Bow-Tie Structures

2020 ◽  
Vol 5 (1) ◽  
pp. 5 ◽  
Author(s):  
Devika Sudsom ◽  
Irén Juhász Junger ◽  
Christoph Döpke ◽  
Tomasz Blachowicz ◽  
Lothar Hahn ◽  
...  
Keyword(s):  
Data Storage ◽  
Vortex Formation ◽  
Basic Research ◽  
Micromagnetic Simulation ◽  
Magnetic Vortex ◽  
Magnetic Memory ◽  
Thick Sample ◽  
Field Orientation ◽  
Micromagnetic Simulations ◽  
Bow Tie

Magnetic vortex structures are of high technological relevance due to their possible application in magnetic memory. Moreover, investigating magnetization reversal via vortex formation is an important topic in basic research. Typically, such vortices are only investigated in homogeneous magnetic materials of diverse shapes. Here, we report for the first time on micromagnetic simulation of vortex formation in magnetic bow-tie nanostructures, comprising alternating parts from iron and permalloy, investigated for two different thicknesses and under different angles of the external magnetic field. While no vortex was found in pure permalloy square, nanoparticles of the dimensions investigated in this study and in case of iron only a relatively thick sample allowed for vortex formation, different numbers of vortices and antivortices were found in the bow-tie structures prepared from both materials, depending on the angular field orientation and the sample thickness. By stabilizing more than one vortex in a confined nanostructure, it is possible to store more than one bit of information in it. Our micromagnetic simulations reveal that such bi-material structures are highly relevant not only for basic research, but also for data storage applications.

scholarly journals Micromagnetic Simulations of Fe and Ni Nanodot Arrays Surrounded by Magnetic or Non-Magnetic Matrices

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 349
Author(s):  
Devika Sudsom ◽  
Andrea Ehrmann
Keyword(s):  
Magnetic Materials ◽  
Data Storage ◽  
Magnetization Reversal ◽  
Hysteresis Loops ◽  
Object Oriented ◽  
Basic Research ◽  
Memory Systems ◽  
The Other ◽  
Micromagnetic Simulations ◽  
Nanodot Arrays

Combining clusters of magnetic materials with a matrix of other magnetic materials is very interesting for basic research because new, possibly technologically applicable magnetic properties or magnetization reversal processes may be found. Here we report on different arrays combining iron and nickel, for example, by surrounding circular nanodots of one material with a matrix of the other or by combining iron and nickel nanodots in air. Micromagnetic simulations were performed using the OOMMF (Object Oriented MicroMagnetic Framework). Our results show that magnetization reversal processes are strongly influenced by neighboring nanodots and the magnetic matrix by which the nanodots are surrounded, respectively, which becomes macroscopically visible by several steps along the slopes of the hysteresis loops. Such material combinations allow for preparing quaternary memory systems, and are thus highly relevant for applications in data storage and processing.

scholarly journals Micromagnetic Simulation of Round Ferromagnetic Nanodots with Varying Roughness and Symmetry

2021 ◽  
Vol 6 (2) ◽  
pp. 19
Author(s):  
Pia Steinmetz ◽  
Andrea Ehrmann
Keyword(s):  
Data Storage ◽  
Magnetization Reversal ◽  
Hysteresis Loops ◽  
Basic Research ◽  
Magnetic Data ◽  
Field Orientation ◽  
Thin Ring ◽  
Production Technologies ◽  
Magnetic States ◽  
The Impact

Magnetic nanodots are of high interest for basic research due to their broad spectrum of possible magnetic states and magnetization reversal processes. Besides, they are of technological interest since they can be applied in magnetic data storage, especially if vortex states occur in closed dots or open rings. While producing such nanorings and nanodots from diverse magnetic materials by lithographic techniques is quite common nowadays, these production technologies are naturally prone to small deviations of the borders of these nanoparticles. Here we investigate the influence of well-defined angular-dependent roughness of the edges, created by building the nanoparticles from small cubes, on the resulting hysteresis loops and magnetization reversal processes in five different round nanodots with varying open areas, from a thin ring to a closed nanodot. By varying the orientation of the external magnetic field, the impact of the angle-dependent roughness can be estimated. Especially for the thinnest ring, significant dependence of the transverse magnetization component on the field orientation can be found.

scholarly journals Neuro-Inspired Signal Processing in Ferromagnetic Nanofibers

Biomimetics ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 32
Author(s):  
Tomasz Blachowicz ◽  
Jacek Grzybowski ◽  
Pawel Steblinski ◽  
Andrea Ehrmann
Keyword(s):  
Data Processing ◽  
Data Storage ◽  
Domain Walls ◽  
Data Transfer ◽  
Synaptic Activity ◽  
Neuromorphic Computing ◽  
Rotating Magnetic Fields ◽  
Micromagnetic Simulations ◽  
Energy Consuming ◽  
Stochastic Data

Computers nowadays have different components for data storage and data processing, making data transfer between these units a bottleneck for computing speed. Therefore, so-called cognitive (or neuromorphic) computing approaches try combining both these tasks, as is done in the human brain, to make computing faster and less energy-consuming. One possible method to prepare new hardware solutions for neuromorphic computing is given by nanofiber networks as they can be prepared by diverse methods, from lithography to electrospinning. Here, we show results of micromagnetic simulations of three coupled semicircle fibers in which domain walls are excited by rotating magnetic fields (inputs), leading to different output signals that can be used for stochastic data processing, mimicking biological synaptic activity and thus being suitable as artificial synapses in artificial neural networks.

Oxidation of graphene ‘bow tie’ nanofuses for permanent, write-once-read-many data storage devices

2013 ◽  
Vol 24 (13) ◽  
pp. 135202 ◽  
Author(s):  
A C Pearson ◽  
S Jamieson ◽  
M R Linford ◽  
B M Lunt ◽  
R C Davis
Keyword(s):  
Data Storage ◽  
Storage Devices ◽  
Bow Tie

scholarly journals A Bis-Monophospholyl Dysprosium Cation Showing Magnetic Hysteresis at 48 Kelvin

2019 ◽  
Author(s):  
Peter Evans ◽  
Daniel Reta ◽  
George F. S. Whitehead ◽  
Nicholas Chilton ◽  
David Mills
Keyword(s):  
Data Storage ◽  
Single Molecule ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Spin Dynamics ◽  
Magnetic Hysteresis ◽  
Relaxation Times ◽  
Magnetic Memory ◽  
Relaxation Processes ◽  
Potential Applications

Single-molecule magnets (SMMs) have potential applications in high-density data storage, but magnetic relaxation times at elevated temperatures must be increased to make them practically useful. <i>Bis</i>-cyclopentadienyl lanthanide sandwich complexes have emerged as the leading candidates for SMMs that show magnetic memory at liquid nitrogen temperatures, but the relaxation mechanisms mediated by aromatic C<sub>5</sub> rings have not been fully established. Here we synthesise a <i>bis</i>-monophospholyl dysprosium SMM [Dy(Dtp)<sub>2</sub>][Al{OC(CF<sub>3</sub>)<sub>3</sub>}<sub>4</sub>] (<b>1</b>, Dtp = {P(C<sup>t</sup>BuCMe)<sub>2</sub>}) by the treatment of <i>in situ</i>-prepared “[Dy(Dtp)<sub>2</sub>(C<sub>3</sub>H<sub>5</sub>)]” with [HNEt<sub>3</sub>][Al{OC(CF<sub>3</sub>)<sub>3</sub>}<sub>4</sub>]. SQUID magnetometry reveals that <b>1</b> has an effective barrier to magnetisation reversal of 1,760 K (1,223 cm<sup>–1</sup>) and magnetic hysteresis up to 48 K. <i>Ab initio</i> calculation of the spin dynamics reveal that transitions out of the ground state are slower in <b>1</b> than in the first reported dysprosocenium SMM, [Dy(Cp<sup>ttt</sup>)<sub>2</sub>][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] (Cp<sup>ttt</sup> = C<sub>5</sub>H<sub>2</sub><sup>t</sup>Bu<sub>3</sub>-1,2,4), however relaxation is faster in <b>1</b> overall due to the compression of electronic energies and to vibrational modes being brought on-resonance by the chemical and structural changes introduced by the <i>bis</i>-Dtp framework. With the preparation and analysis of <b>1</b> we are thus able to further refine our understanding of relaxation processes operating in <i>bis</i>-C<sub>5</sub>/C<sub>4</sub>P sandwich lanthanide SMMs, which is the necessary first step towards rationally achieving higher magnetic blocking temperatures in these systems in future.

Dynamic behavior of azobenzene polyester used for holographic data storage

2001 ◽  
Vol 674 ◽  
Author(s):  
Árpád Kerekes ◽  
E. Lörincz ◽  
Sz. Sajti ◽  
P. Várhegyi ◽  
P. S. Ramanujam ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Data Storage ◽  
Intensity Ratio ◽  
Holographic Recording ◽  
Holographic Data Storage ◽  
Thick Sample ◽  
Model Experiments ◽  
Optimal Intensity ◽  
532 Nm ◽  
Higher Sensitivity

ABSTRACTDynamic behavior of thin photoaddressable polyester films was studied. The saturation process due to Fourier holographic recording was investigated. Model experiments show an optimal intensity ratio of the object and reference beams, where the highest efficiency occurs. This ratio is inversely proportional to the reference intensity. The material has a significantly higher sensitivity at 407 nm than at 532 nm. For 1 μm thick sample an M# of 0.25 was measurable.

Magnetic vortex formation in hollow Fe3O4 submicron particles studied using first-order reversal curves

2020 ◽  
Vol 512 ◽  
pp. 167012
Author(s):  
Momoko Chiba ◽  
Satoru Kobayashi ◽  
Kazuki Noguchi ◽  
Takeshi Murakami ◽  
Jerzy A. Szpunar ◽  
...  
Keyword(s):  
Vortex Formation ◽  
Magnetic Vortex ◽  
Submicron Particles ◽  
First Order

scholarly journals Micromagnetic Simulations of Submicron Vortex Structures for the Detection of Superparamagnetic Labels

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5819
Author(s):  
Lukas Wetterau ◽  
Claas Abert ◽  
Dieter Suess ◽  
Manfred Albrecht ◽  
Bernd Witzigmann
Keyword(s):  
Electric Potential ◽  
Giant Magnetoresistance ◽  
Spin Diffusion ◽  
Magnetic Vortex ◽  
Electric Response ◽  
Stray Field ◽  
Soft Magnetic ◽  
Micromagnetic Simulations ◽  
Gmr Sensor ◽  
Magnetization Change

We present a numerical investigation on the detection of superparamagnetic labels using a giant magnetoresistance (GMR) vortex structure. For this purpose, the Landau–Lifshitz–Gilbert equation was solved numerically applying an external z-field for the activation of the superparamagnetic label. Initially, the free layer’s magnetization change due to the stray field of the label is simulated. The electric response of the GMR sensor is calculated by applying a self-consistent spin-diffusion model to the precomputed magnetization configurations. It is shown that the soft-magnetic free layer reacts on the stray field of the label by shifting the magnetic vortex orthogonally to the shift direction of the label. As a consequence, the electric potential of the GMR sensor changes significantly for label shifts parallel or antiparallel to the pinning of the fixed layer. Depending on the label size and its distance to the sensor, the GMR sensor responds, changing the electric potential from 26.6 mV to 28.3 mV.

Magnetic skyrmions in FePt nanoparticles having Reuleaux 3D geometry: a micromagnetic simulation study

Nanoscale ◽  
2019 ◽  
Vol 11 (42) ◽  
pp. 20102-20114 ◽  
Author(s):  
Vasileios D. Stavrou ◽  
Drosos Kourounis ◽  
Konstantinos Dimakopoulos ◽  
Ioannis Panagiotopoulos ◽  
Leonidas N. Gergidis
Keyword(s):  
Finite Element ◽  
Simulation Study ◽  
Magnetization Reversal ◽  
Magnetocrystalline Anisotropy ◽  
Micromagnetic Simulation ◽  
Fept Nanoparticles ◽  
External Fields ◽  
Micromagnetic Simulations ◽  
3D Geometry ◽  
Magnetic Skyrmions

The magnetization reversal in magnetic FePt nanoelements having Reuleaux 3D geometry is studied using Finite Element micromagnetic simulations. Multiple skyrmions are formed for a range of external fields and magnetocrystalline anisotropy values.

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.

Sign in / Sign up

Export Citation Format

Share Document