Numerical simulations of magnetic materials with MD-GRAPE

Curvature induced anisotropy

B. G. Elmegreen, R. Koch, Kenji Yasuoka, H. Furusawa, T. Narumi, R. Susukita, T. Ebisuzaki

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The time development of an array of magnetic dipoles representing the internal magnetization of a thin film is calculated using a hardware accelerator, MD-GRAPE, for the determination of the magnetic vector potential. The results for single-layer arrays of dipoles are compared with the analogous results obtained from an FFT method and found to be in reasonable agreement. Three-dimensional MD-GRAPE simulations with sinusoidal deformations illustrate the utility of the hardware accelerator in cases that cannot be solved easily with FFT methods. The deformations give the internal field an asymmetry with components parallel to the wave crest, leading to significant changes in the critical external fields required for switching. These changes occur even for small wave amplitudes, comparable to or less than the layer thickness. Layer curvature affects the astroid pattern of critical field strengths by shifting the threshold to lower absolute values of the hard axis field when the curvature is in the easy axis direction, and lower absolute values of the easy axis field when the curvature is in the hard axis direction. This effect of curvature differs from orange peel coupling between two layers because here there is only one layer, and because orange peel coupling shifts the whole astroid pattern as a result of an effective field bias, whereas here the pattern shape is changed without any centroid shift.

Original languageEnglish
Pages (from-to)39-48
Number of pages10
JournalJournal of Magnetism and Magnetic Materials
Volume250
DOIs
Publication statusPublished - 2002 Sep

Fingerprint

Magnetic materials
magnetic materials
Fast Fourier transforms
Particle accelerators
Anisotropy
curvature
Hardware
anisotropy
Computer simulation
fast Fourier transformations
Magnetization
simulation
hardware
accelerators
Thin films
shift
magnetic dipoles
centroids
field strength
Direction compound

Keywords

  • Accelerator hardware
  • Curvature anisotropy
  • Micromagnetic methods
  • Micromagnetics
  • Non-uniform grid spacing

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Numerical simulations of magnetic materials with MD-GRAPE : Curvature induced anisotropy. / Elmegreen, B. G.; Koch, R.; Yasuoka, Kenji; Furusawa, H.; Narumi, T.; Susukita, R.; Ebisuzaki, T.

In: Journal of Magnetism and Magnetic Materials, Vol. 250, 09.2002, p. 39-48.

Research output: Contribution to journalArticle

Elmegreen, B. G. ; Koch, R. ; Yasuoka, Kenji ; Furusawa, H. ; Narumi, T. ; Susukita, R. ; Ebisuzaki, T. / Numerical simulations of magnetic materials with MD-GRAPE : Curvature induced anisotropy. In: Journal of Magnetism and Magnetic Materials. 2002 ; Vol. 250. pp. 39-48.
@article{14f6ca2ec3054d9785ddc3eca1053bc3,
title = "Numerical simulations of magnetic materials with MD-GRAPE: Curvature induced anisotropy",
abstract = "The time development of an array of magnetic dipoles representing the internal magnetization of a thin film is calculated using a hardware accelerator, MD-GRAPE, for the determination of the magnetic vector potential. The results for single-layer arrays of dipoles are compared with the analogous results obtained from an FFT method and found to be in reasonable agreement. Three-dimensional MD-GRAPE simulations with sinusoidal deformations illustrate the utility of the hardware accelerator in cases that cannot be solved easily with FFT methods. The deformations give the internal field an asymmetry with components parallel to the wave crest, leading to significant changes in the critical external fields required for switching. These changes occur even for small wave amplitudes, comparable to or less than the layer thickness. Layer curvature affects the astroid pattern of critical field strengths by shifting the threshold to lower absolute values of the hard axis field when the curvature is in the easy axis direction, and lower absolute values of the easy axis field when the curvature is in the hard axis direction. This effect of curvature differs from orange peel coupling between two layers because here there is only one layer, and because orange peel coupling shifts the whole astroid pattern as a result of an effective field bias, whereas here the pattern shape is changed without any centroid shift.",
keywords = "Accelerator hardware, Curvature anisotropy, Micromagnetic methods, Micromagnetics, Non-uniform grid spacing",
author = "Elmegreen, {B. G.} and R. Koch and Kenji Yasuoka and H. Furusawa and T. Narumi and R. Susukita and T. Ebisuzaki",
year = "2002",
month = "9",
doi = "10.1016/S0304-8853(02)00344-X",
language = "English",
volume = "250",
pages = "39--48",
journal = "Journal of Magnetism and Magnetic Materials",
issn = "0304-8853",
publisher = "Elsevier",

}

TY - JOUR

T1 - Numerical simulations of magnetic materials with MD-GRAPE

T2 - Curvature induced anisotropy

AU - Elmegreen, B. G.

AU - Koch, R.

AU - Yasuoka, Kenji

AU - Furusawa, H.

AU - Narumi, T.

AU - Susukita, R.

AU - Ebisuzaki, T.

PY - 2002/9

Y1 - 2002/9

N2 - The time development of an array of magnetic dipoles representing the internal magnetization of a thin film is calculated using a hardware accelerator, MD-GRAPE, for the determination of the magnetic vector potential. The results for single-layer arrays of dipoles are compared with the analogous results obtained from an FFT method and found to be in reasonable agreement. Three-dimensional MD-GRAPE simulations with sinusoidal deformations illustrate the utility of the hardware accelerator in cases that cannot be solved easily with FFT methods. The deformations give the internal field an asymmetry with components parallel to the wave crest, leading to significant changes in the critical external fields required for switching. These changes occur even for small wave amplitudes, comparable to or less than the layer thickness. Layer curvature affects the astroid pattern of critical field strengths by shifting the threshold to lower absolute values of the hard axis field when the curvature is in the easy axis direction, and lower absolute values of the easy axis field when the curvature is in the hard axis direction. This effect of curvature differs from orange peel coupling between two layers because here there is only one layer, and because orange peel coupling shifts the whole astroid pattern as a result of an effective field bias, whereas here the pattern shape is changed without any centroid shift.

AB - The time development of an array of magnetic dipoles representing the internal magnetization of a thin film is calculated using a hardware accelerator, MD-GRAPE, for the determination of the magnetic vector potential. The results for single-layer arrays of dipoles are compared with the analogous results obtained from an FFT method and found to be in reasonable agreement. Three-dimensional MD-GRAPE simulations with sinusoidal deformations illustrate the utility of the hardware accelerator in cases that cannot be solved easily with FFT methods. The deformations give the internal field an asymmetry with components parallel to the wave crest, leading to significant changes in the critical external fields required for switching. These changes occur even for small wave amplitudes, comparable to or less than the layer thickness. Layer curvature affects the astroid pattern of critical field strengths by shifting the threshold to lower absolute values of the hard axis field when the curvature is in the easy axis direction, and lower absolute values of the easy axis field when the curvature is in the hard axis direction. This effect of curvature differs from orange peel coupling between two layers because here there is only one layer, and because orange peel coupling shifts the whole astroid pattern as a result of an effective field bias, whereas here the pattern shape is changed without any centroid shift.

KW - Accelerator hardware

KW - Curvature anisotropy

KW - Micromagnetic methods

KW - Micromagnetics

KW - Non-uniform grid spacing

UR - http://www.scopus.com/inward/record.url?scp=0036750778&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036750778&partnerID=8YFLogxK

U2 - 10.1016/S0304-8853(02)00344-X

DO - 10.1016/S0304-8853(02)00344-X

M3 - Article

VL - 250

SP - 39

EP - 48

JO - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

SN - 0304-8853

ER -