1,720,977 research outputs found
Magnetic field dependence of magnetization reversal behavior in Co/Pt multilayers
No full textMagnetic field dependence of magnetization reversal in Co/Pt multilayers has been quantitatively investigated. Serial samples of Co/Pt multilayers have been prepared by dc magnetron sputtering under various Ar pressures. Magnetization reversal was monitored by magnetization viscosity measurement and direct domain observation using a magneto-optical microscope system. The wall-motion speed V and the nucleation rate R were determined using a domain reversal model based on time-resolved domain reversal patterns. Both V and R were found to be exponentially dependent on the reversing applied field. From the exponential dependence, the activation volumes of the wall-motion and nucleation could be determined based on a thermally activated relaxation model. The wall-motion activation volume was revealed to be slightly larger than the nucleation activation volume. (C) 2001 American Institute of Physics.This work was supported by the Korean Ministry of Science
and Technology through the Creative Research Initiatives
Project
Dependences of the activation volumes on Ar sputtering pressure in Co/Pt multilayers prepared by dc magnetron sputtering
No full textWe investigated the wall-motion and nucleation activation volumes of Co/Pt multilayer films prepared by dc magnetron sputtering under various Ar sputtering pressures. Delicate analysis of time-resolved domain evolution patterns reveals that the nucleation activation volume is generally smaller than the wall-motion activation volume in all the samples, which is consistent with the nucleation-dominant magnetization reversal behavior observed in this system. Interestingly, the activation volume is found to decrease with increasing Ar pressure, despite a decreasing trend in saturation magnetization. Decreasing grain size with increasing Ar pressure, smaller than the typical size of a Co single domain, is believed to be the origin of the unexpected observation. (C) 2002 American Institute of Physics.This work was supported by the Korean Ministry of Science
and Technology through the Creative Research Initiatives
Project
Self-Similar Magnetic Domain Evolution Pattern During Magnetization Reversal in Co/Pt Multilayers
No full text
Self-Similar Magnetic Domain Evolution Pattern During Magnetization Reversal in Co/Pt Multilayers
No full textFractal analysis of time-resolved magnetic domain patterns in Co/Pd multilayer with varying number of repeats
No full textWe investigate the fractal behavior of magnetic domain together with analysis of dynamic reversal behavior in Co/Pd multilayer films prepared with different number of repeats n. We utilize a novel magneto-optical microscope magnetometer technique to visualize the time-resolved domain evolution patterns in these films. Quantitative analysis of the time-resolved domain evolution patterns allows us to determine the fractal dimension D-f and the reversal ratio V/R depending on n, where V/R represents the counterbalance between the wall-motion speed V and the nucleation rate R. As n increases, domain shape becomes more ragged and complex and thus, D-f increases. Interestingly enough, the change in D-f clearly seems to be coupled to the change in V/R with varying n, which implies that the correlation between Df and V/R is mediated via the distributed defects. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.This work was supported through the Creative Research Initiatives Project of the Korean
Ministry of Science and Technology
Correlation between fractal dimension and reversal behavior of magnetic domain in Co/Pd nanomultilayers
No full textWe report the experimental finding that there is a close correlation between fractal geometry and reversal mechanism of magnetic domain in Co/Pd nanomultilayers. We have measured the fractal dimension D-f of magnetic domain as well as the wall-motion speed V, the nucleation rate R, and the reversal ratio V/R in Co/Pd nanomultilayer films during magnetization reversal via time-resolved direct domain observation. Interestingly enough, D-f is inversely related to the reversal ratio V/R, which could be quantitatively explained using a micromagnetic simulation based on thermally activated relaxation model. We find that the fractal dimension is a crucial parameter to characterize magnetization reversal behavior as well as jaggedness of domain geometry. (C) 2003 American Institute of Physics.This work was supported through the Creative Research
Initiatives Project of the Korean Ministry of Science and
Technology
Activation volumes of wall-motion and nucleation processes in Co-based ferromagnetic multilayer films
No full textActivation volumes of the wall-motion and nucleation processes in Co-based multilayer films were characterized from time-resolved domain evolution patterns, These activation volumes were both sensitive to the multilayer structure as well as the film preparation condition. The two activation volumes were generally unequal with each other and the inequality directly influenced on magnetization reversal behavior. (C) 2002 Elsevier Science B.V. All rights reserved.This work was supported by the Creative Research
Initiatives Project of the Ministry of Science and
Technology of Korea
Micromagnetic simulation of magnetization reversal behavior of Co/Pt multilayer nanodot array prepared by colloidal lithograpy
No full textWe report here the magnetization reversal study of dipolar coupled Ising-like dot array, where nanodot arrays of Co/Pt multilayer with perpendicular magnetic anisotropy are patterned in a self-assembled way based on a colloidal lithography. To investigate real magnetization reversal behavior of dot arrays, we have taken an AFM image of a dot array to obtain quantitative topological information of dot array and carried out micromagnetic simulation over the area considering the topological profile obtained from the AFM image. We find that there exists a ripple-like domain structure mainly governed by the dipolar interdot interactions in the dot array, which is experimentally confirmed by the MFM observation. (C) 2004 Published by Elsevier B.V.This work was supported through the Creative
Research Initiatives Project of the Korean Minis-
try of Science and Technology
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