---
_id: '1426'
abstract:
- lang: eng
text: Round magnetic nano-dots belong to the frequently investigated magnetic nanostructures
since they can often reverse magnetization via a vortex state which is characterized
by low stray fields, making them useful for data storage applications. Nano-rings,
with an open aperture in the middle, regularly show flux-closed vortex states
without a vortex core, again reducing stray fields. Here we theoretically investigate
“Pac-Man” shaped iron nanostructures with varying aperture, i.e. structures ranging
from a thin ring to a solid cylinder with a triangular cut. Our results show that
in most cases, a vortex-like state without vortex core along the whole nanostructure
occurs during magnetization reversal. Depending on the angle of the external magnetic
field and the nanostructure thickness, different magnetization reversal processes
have been found, including domain wall nucleation and propagation as well as small
vortex states with cores. The occurrence of such special magnetic states can be
attributed to the interaction of the shape anisotropy with the relatively high
magneto-crystalline anisotropy of iron. Our simulations reveal the possibilities
to use such structures for data storage applications as well as their importance
in basic research, enabling formation of asymmetric magnetic structures beyond
common onion and symmetric vortex states.
article_number: '168205'
article_type: original
author:
- first_name: Fatima-Zohra
full_name: Bachar, Fatima-Zohra
last_name: Bachar
- first_name: Christian
full_name: Schröder, Christian
id: '35809'
last_name: Schröder
orcid: 0000-0002-6391-6548
orcid_put_code_url: https://api.orcid.org/v2.0/0000-0002-6391-6548/work/96660667
- first_name: Andrea
full_name: Ehrmann, Andrea
id: '223776'
last_name: Ehrmann
orcid: 0000-0003-0695-3905
orcid_put_code_url: https://api.orcid.org/v2.0/0000-0003-0695-3905/work/96660668
citation:
alphadin: 'Bachar, Fatima-Zohra ;
Schröder, Christian ; Ehrmann,
Andrea: Magnetization reversal in Pac-Man shaped Fe nanostructures with
varying aperture. In: Journal of Magnetism and Magnetic Materials Bd. 537,
Elsevier BV (2021)'
ama: Bachar F-Z, Schröder C, Ehrmann A. Magnetization reversal in Pac-Man shaped
Fe nanostructures with varying aperture. Journal of Magnetism and Magnetic
Materials. 2021;537. doi:10.1016/j.jmmm.2021.168205
apa: Bachar, F.-Z., Schröder, C., & Ehrmann, A. (2021). Magnetization reversal
in Pac-Man shaped Fe nanostructures with varying aperture. Journal of Magnetism
and Magnetic Materials, 537. https://doi.org/10.1016/j.jmmm.2021.168205
bibtex: '@article{Bachar_Schröder_Ehrmann_2021, title={Magnetization reversal in
Pac-Man shaped Fe nanostructures with varying aperture}, volume={537}, DOI={10.1016/j.jmmm.2021.168205},
number={168205}, journal={Journal of Magnetism and Magnetic Materials}, publisher={Elsevier
BV}, author={Bachar, Fatima-Zohra and Schröder, Christian and Ehrmann, Andrea},
year={2021} }'
chicago: Bachar, Fatima-Zohra, Christian Schröder, and Andrea Ehrmann. “Magnetization
Reversal in Pac-Man Shaped Fe Nanostructures with Varying Aperture.” Journal
of Magnetism and Magnetic Materials 537 (2021). https://doi.org/10.1016/j.jmmm.2021.168205.
ieee: F.-Z. Bachar, C. Schröder, and A. Ehrmann, “Magnetization reversal in Pac-Man
shaped Fe nanostructures with varying aperture,” Journal of Magnetism and Magnetic
Materials, vol. 537, 2021.
mla: Bachar, Fatima-Zohra, et al. “Magnetization Reversal in Pac-Man Shaped Fe Nanostructures
with Varying Aperture.” Journal of Magnetism and Magnetic Materials, vol.
537, 168205, Elsevier BV, 2021, doi:10.1016/j.jmmm.2021.168205.
short: F.-Z. Bachar, C. Schröder, A. Ehrmann, Journal of Magnetism and Magnetic
Materials 537 (2021).
date_created: 2021-07-06T09:07:19Z
date_updated: 2023-03-08T09:29:40Z
doi: 10.1016/j.jmmm.2021.168205
intvolume: ' 537'
keyword:
- Magnetic nanostructures Micromagnetic simulation Magnetization reversal Iron Vortex
state Domain walls Shape anisotropy
language:
- iso: eng
main_file_link:
- url: https://doi.org/10.1016/j.jmmm.2021.168205
project:
- _id: f89a05bb-bcea-11ed-9442-ed382659bc06
name: Bielefelder Institut für Angewandte Materialforschung
publication: Journal of Magnetism and Magnetic Materials
publication_identifier:
issn:
- '03048853'
publication_status: published
publisher: Elsevier BV
quality_controlled: '1'
status: public
title: Magnetization reversal in Pac-Man shaped Fe nanostructures with varying aperture
type: journal_article
user_id: '35809'
volume: 537
year: '2021'
...
---
_id: '1603'
abstract:
- lang: eng
text: " 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.\r\n
\ "
article_number: '19'
article_type: original
author:
- first_name: Pia
full_name: Steinmetz, Pia
last_name: Steinmetz
- first_name: Andrea
full_name: Ehrmann, Andrea
id: '223776'
last_name: Ehrmann
orcid: 0000-0003-0695-3905
orcid_put_code_url: https://api.orcid.org/v2.0/0000-0003-0695-3905/work/105572063
citation:
alphadin: 'Steinmetz, Pia ; Ehrmann, Andrea: Micromagnetic Simulation
of Round Ferromagnetic Nanodots with Varying Roughness and Symmetry. In: Condensed
Matter Bd. 6, MDPI AG (2021), Nr. 2'
ama: Steinmetz P, Ehrmann A. Micromagnetic Simulation of Round Ferromagnetic Nanodots
with Varying Roughness and Symmetry. Condensed Matter. 2021;6(2). doi:10.3390/condmat6020019
apa: Steinmetz, P., & Ehrmann, A. (2021). Micromagnetic Simulation of Round
Ferromagnetic Nanodots with Varying Roughness and Symmetry. Condensed Matter,
6(2). https://doi.org/10.3390/condmat6020019
bibtex: '@article{Steinmetz_Ehrmann_2021, title={Micromagnetic Simulation of Round
Ferromagnetic Nanodots with Varying Roughness and Symmetry}, volume={6}, DOI={10.3390/condmat6020019}, number={219},
journal={Condensed Matter}, publisher={MDPI AG}, author={Steinmetz, Pia and Ehrmann,
Andrea}, year={2021} }'
chicago: Steinmetz, Pia, and Andrea Ehrmann. “Micromagnetic Simulation of Round
Ferromagnetic Nanodots with Varying Roughness and Symmetry.” Condensed Matter
6, no. 2 (2021). https://doi.org/10.3390/condmat6020019.
ieee: P. Steinmetz and A. Ehrmann, “Micromagnetic Simulation of Round Ferromagnetic
Nanodots with Varying Roughness and Symmetry,” Condensed Matter, vol. 6,
no. 2, 2021.
mla: Steinmetz, Pia, and Andrea Ehrmann. “Micromagnetic Simulation of Round Ferromagnetic
Nanodots with Varying Roughness and Symmetry.” Condensed Matter, vol. 6,
no. 2, 19, MDPI AG, 2021, doi:10.3390/condmat6020019.
short: P. Steinmetz, A. Ehrmann, Condensed Matter 6 (2021).
date_created: 2022-01-01T14:13:48Z
date_updated: 2022-01-01T15:08:21Z
department:
- _id: '103'
doi: 10.3390/condmat6020019
intvolume: ' 6'
issue: '2'
keyword:
- OOMMF (Object Orientated MicroMagnetic Framework)
- nanostructure
- iron
- vortex state
- domain wall
- rough borders
language:
- iso: eng
license: https://creativecommons.org/licenses/by/4.0/
main_file_link:
- open_access: '1'
url: https://doi.org/10.3390/condmat6020019
oa: '1'
publication: Condensed Matter
publication_identifier:
eissn:
- 2410-3896
publication_status: published
publisher: MDPI AG
quality_controlled: '1'
status: public
title: Micromagnetic Simulation of Round Ferromagnetic Nanodots with Varying Roughness
and Symmetry
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: '223776'
volume: 6
year: '2021'
...
---
_id: '1616'
abstract:
- lang: eng
text: Electrospun nanofibers produced from magnetic materials form a magnetic network
which may be used for neuromorphic computing and other novel applications. While
the influence of bending radii on the magnetization reversal in such nanofibers
was already discussed in the literature, the often occurring beads along the fibers
have not yet been investigated in detail. It can be assumed that such beads will
support domain wall formation due to a reduction of the relative impact of the
shape anisotropy, in this way influencing magnetization reversal along the fiber.
Here, we simulate magnetization reversal processes in iron, nickel, cobalt and
magnetite fibers with a bead in the middle, produced in three typical dimensions
gained by electrospinning. In most cases a vortex state occurs during magnetization
reversal, independent from the material and the dimensions. For some angular orientations
of the external magnetic field, double-vortex or meander states are visible, usually
also followed by vortex states. These simulations underline the strong and highly
reliable impact of beads along electrospun fibers, making these structures useful
for data storage, transport and other applications.
article_number: '167855'
article_type: original
author:
- first_name: Fedi
full_name: Amini, Fedi
last_name: Amini
- first_name: Tomasz
full_name: Blachowicz, Tomasz
last_name: Blachowicz
- first_name: Andrea
full_name: Ehrmann, Andrea
id: '223776'
last_name: Ehrmann
orcid: 0000-0003-0695-3905
orcid_put_code_url: https://api.orcid.org/v2.0/0000-0003-0695-3905/work/105571785
citation:
alphadin: 'Amini, Fedi ; Blachowicz,
Tomasz ; Ehrmann, Andrea:
Systematic study of magnetization reversal in beaded fibers from different magnetic
materials. In: Journal of Magnetism and Magnetic Materials Bd. 529, Elsevier
BV (2021)'
ama: Amini F, Blachowicz T, Ehrmann A. Systematic study of magnetization reversal
in beaded fibers from different magnetic materials. Journal of Magnetism and
Magnetic Materials. 2021;529. doi:10.1016/j.jmmm.2021.167855
apa: Amini, F., Blachowicz, T., & Ehrmann, A. (2021). Systematic study of magnetization
reversal in beaded fibers from different magnetic materials. Journal of Magnetism
and Magnetic Materials, 529. https://doi.org/10.1016/j.jmmm.2021.167855
bibtex: '@article{Amini_Blachowicz_Ehrmann_2021, title={Systematic study of magnetization
reversal in beaded fibers from different magnetic materials}, volume={529}, DOI={10.1016/j.jmmm.2021.167855},
number={167855}, journal={Journal of Magnetism and Magnetic Materials}, publisher={Elsevier
BV}, author={Amini, Fedi and Blachowicz, Tomasz and Ehrmann, Andrea}, year={2021}
}'
chicago: Amini, Fedi, Tomasz Blachowicz, and Andrea Ehrmann. “Systematic Study of
Magnetization Reversal in Beaded Fibers from Different Magnetic Materials.” Journal
of Magnetism and Magnetic Materials 529 (2021). https://doi.org/10.1016/j.jmmm.2021.167855.
ieee: F. Amini, T. Blachowicz, and A. Ehrmann, “Systematic study of magnetization
reversal in beaded fibers from different magnetic materials,” Journal of Magnetism
and Magnetic Materials, vol. 529, 2021.
mla: Amini, Fedi, et al. “Systematic Study of Magnetization Reversal in Beaded Fibers
from Different Magnetic Materials.” Journal of Magnetism and Magnetic Materials,
vol. 529, 167855, Elsevier BV, 2021, doi:10.1016/j.jmmm.2021.167855.
short: F. Amini, T. Blachowicz, A. Ehrmann, Journal of Magnetism and Magnetic Materials
529 (2021).
date_created: 2022-01-01T14:27:47Z
date_updated: 2022-01-01T15:01:28Z
department:
- _id: '103'
doi: 10.1016/j.jmmm.2021.167855
intvolume: ' 529'
keyword:
- Magnetic nanostructures Micromagnetic simulation Magnetization reversal Iron Nickel
Cobalt Magnetite Vortex state Domain walls Shape anisotropy
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.1016/j.jmmm.2021.167855
oa: '1'
publication: Journal of Magnetism and Magnetic Materials
publication_identifier:
issn:
- '03048853'
publication_status: published
publisher: Elsevier BV
quality_controlled: '1'
status: public
title: Systematic study of magnetization reversal in beaded fibers from different
magnetic materials
type: journal_article
user_id: '223776'
volume: 529
year: '2021'
...
---
_id: '669'
abstract:
- lang: eng
text: Magnetic vortices belong to the possibilities to store information in magnetic
structures. Understanding their nucleation and propagation is also of interest
in basic research. While vortices are usually examined in particles of homogeneous
material, here we give an overview of the impact of borders between two materials,
i.e. iron and permalloy, on magnetization reversal and vortex formation in double-wedges
as well as adjacent rectangles of different thickness. While former investigations
of pure iron nanoparticles of similar dimensions revealed different magnetization
reversal magnetisms without vortex, with one or two vortices, the addition of
a permalloy part stabilized the magnetization reversal so that in all situations
under investigation, a single vortex was observed. Our simulations underline the
technological importance of such double-material structures for the preparation
of nanostructures for storage devices with reliable magnetization reversal processes,
stable against erroneous modifications of nanoparticle dimensions and magnetic
field orientations.
article_number: '167294'
article_type: original
author:
- first_name: Devika
full_name: Sudsom, Devika
last_name: Sudsom
- first_name: Tomasz
full_name: Blachowicz, Tomasz
last_name: Blachowicz
- first_name: Lothar
full_name: Hahn, Lothar
last_name: Hahn
- first_name: Andrea
full_name: Ehrmann, Andrea
id: '223776'
last_name: Ehrmann
orcid: 0000-0003-0695-3905
citation:
alphadin: 'Sudsom, Devika ; Blachowicz, Tomasz ; Hahn,
Lothar ; Ehrmann, Andrea:
Vortex nucleation and propagation in magnetic double-wedges and semi-squares for
reliable quaternary storage systems. In: Journal of Magnetism and Magnetic
Materials Bd. 514 (2020)'
ama: Sudsom D, Blachowicz T, Hahn L, Ehrmann A. Vortex nucleation and propagation
in magnetic double-wedges and semi-squares for reliable quaternary storage systems.
Journal of Magnetism and Magnetic Materials. 2020;514. doi:10.1016/j.jmmm.2020.167294
apa: Sudsom, D., Blachowicz, T., Hahn, L., & Ehrmann, A. (2020). Vortex nucleation
and propagation in magnetic double-wedges and semi-squares for reliable quaternary
storage systems. Journal of Magnetism and Magnetic Materials, 514.
https://doi.org/10.1016/j.jmmm.2020.167294
bibtex: '@article{Sudsom_Blachowicz_Hahn_Ehrmann_2020, title={Vortex nucleation
and propagation in magnetic double-wedges and semi-squares for reliable quaternary
storage systems}, volume={514}, DOI={10.1016/j.jmmm.2020.167294},
number={167294}, journal={Journal of Magnetism and Magnetic Materials}, author={Sudsom,
Devika and Blachowicz, Tomasz and Hahn, Lothar and Ehrmann, Andrea}, year={2020}
}'
chicago: Sudsom, Devika, Tomasz Blachowicz, Lothar Hahn, and Andrea Ehrmann. “Vortex
Nucleation and Propagation in Magnetic Double-Wedges and Semi-Squares for Reliable
Quaternary Storage Systems.” Journal of Magnetism and Magnetic Materials
514 (2020). https://doi.org/10.1016/j.jmmm.2020.167294.
ieee: D. Sudsom, T. Blachowicz, L. Hahn, and A. Ehrmann, “Vortex nucleation and
propagation in magnetic double-wedges and semi-squares for reliable quaternary
storage systems,” Journal of Magnetism and Magnetic Materials, vol. 514,
2020.
mla: Sudsom, Devika, et al. “Vortex Nucleation and Propagation in Magnetic Double-Wedges
and Semi-Squares for Reliable Quaternary Storage Systems.” Journal of Magnetism
and Magnetic Materials, vol. 514, 167294, 2020, doi:10.1016/j.jmmm.2020.167294.
short: D. Sudsom, T. Blachowicz, L. Hahn, A. Ehrmann, Journal of Magnetism and Magnetic
Materials 514 (2020).
date_created: 2021-01-03T16:51:38Z
date_updated: 2021-05-21T07:09:59Z
department:
- _id: '103'
doi: 10.1016/j.jmmm.2020.167294
intvolume: ' 514'
keyword:
- Magnetic nanostructures
- Wedges
- Micromagnetic simulation
- Vortex
- Magnetization reversal
- Iron
- Permalloy
- Lithography
language:
- iso: eng
publication: Journal of Magnetism and Magnetic Materials
publication_identifier:
issn:
- 0304-8853
publication_status: published
quality_controlled: '1'
status: public
title: Vortex nucleation and propagation in magnetic double-wedges and semi-squares
for reliable quaternary storage systems
type: journal_article
user_id: '237837'
volume: 514
year: '2020'
...
---
_id: '635'
abstract:
- lang: eng
text: 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.
article_number: '5'
article_type: original
author:
- first_name: Devika
full_name: Sudsom, Devika
last_name: Sudsom
- first_name: Irén
full_name: Juhász Junger, Irén
last_name: Juhász Junger
- first_name: Christoph
full_name: Döpke, Christoph
last_name: Döpke
- first_name: Tomasz
full_name: Blachowicz, Tomasz
last_name: Blachowicz
- first_name: Lothar
full_name: Hahn, Lothar
last_name: Hahn
- first_name: Andrea
full_name: Ehrmann, Andrea
id: '223776'
last_name: Ehrmann
orcid: 0000-0003-0695-3905
citation:
alphadin: 'Sudsom, Devika ; Juhász Junger, Irén ; Döpke,
Christoph ; Blachowicz, Tomasz
; Hahn, Lothar ; Ehrmann,
Andrea: Micromagnetic Simulation of Vortex Development in Magnetic Bi-Material
Bow-Tie Structures. In: Condensed Matter Bd. 5 (2020), Nr. 1'
ama: Sudsom D, Juhász Junger I, Döpke C, Blachowicz T, Hahn L, Ehrmann A. Micromagnetic
Simulation of Vortex Development in Magnetic Bi-Material Bow-Tie Structures. Condensed
Matter. 2020;5(1). doi:10.3390/condmat5010005
apa: Sudsom, D., Juhász Junger, I., Döpke, C., Blachowicz, T., Hahn, L., & Ehrmann,
A. (2020). Micromagnetic Simulation of Vortex Development in Magnetic Bi-Material
Bow-Tie Structures. Condensed Matter, 5(1). https://doi.org/10.3390/condmat5010005
bibtex: '@article{Sudsom_Juhász Junger_Döpke_Blachowicz_Hahn_Ehrmann_2020, title={Micromagnetic
Simulation of Vortex Development in Magnetic Bi-Material Bow-Tie Structures},
volume={5}, DOI={10.3390/condmat5010005},
number={15}, journal={Condensed Matter}, author={Sudsom, Devika and Juhász Junger,
Irén and Döpke, Christoph and Blachowicz, Tomasz and Hahn, Lothar and Ehrmann,
Andrea}, year={2020} }'
chicago: Sudsom, Devika, Irén Juhász Junger, Christoph Döpke, Tomasz Blachowicz,
Lothar Hahn, and Andrea Ehrmann. “Micromagnetic Simulation of Vortex Development
in Magnetic Bi-Material Bow-Tie Structures.” Condensed Matter 5, no. 1
(2020). https://doi.org/10.3390/condmat5010005.
ieee: D. Sudsom, I. Juhász Junger, C. Döpke, T. Blachowicz, L. Hahn, and A. Ehrmann,
“Micromagnetic Simulation of Vortex Development in Magnetic Bi-Material Bow-Tie
Structures,” Condensed Matter, vol. 5, no. 1, 2020.
mla: Sudsom, Devika, et al. “Micromagnetic Simulation of Vortex Development in Magnetic
Bi-Material Bow-Tie Structures.” Condensed Matter, vol. 5, no. 1, 5, 2020,
doi:10.3390/condmat5010005.
short: D. Sudsom, I. Juhász Junger, C. Döpke, T. Blachowicz, L. Hahn, A. Ehrmann,
Condensed Matter 5 (2020).
date_created: 2021-01-03T14:42:18Z
date_updated: 2021-05-19T14:01:34Z
ddc:
- '530'
department:
- _id: '103'
doi: 10.3390/condmat5010005
file:
- access_level: open_access
content_type: application/pdf
creator: aehrmann
date_created: 2021-01-03T14:41:31Z
date_updated: 2021-01-03T14:41:31Z
file_id: '636'
file_name: _2020_Sudsom_CondMatter5_5_corr.pdf
file_size: 4886370
relation: main_file
success: 1
file_date_updated: 2021-01-03T14:41:31Z
funded_apc: '1'
has_accepted_license: '1'
intvolume: ' 5'
issue: '1'
keyword:
- magnetic nanostructures
- micromagnetic simulation
- bow-tie structure
- vortex
- magnetization reversal
- iron
- permalloy
- lithography
language:
- iso: eng
oa: '1'
publication: Condensed Matter
publication_identifier:
issn:
- 2410-3896
publication_status: published
quality_controlled: '1'
status: public
title: Micromagnetic Simulation of Vortex Development in Magnetic Bi-Material Bow-Tie
Structures
type: journal_article
user_id: '237837'
volume: 5
year: '2020'
...