Field dependence of magnetic viscosity of CoCrTa in-plane media

Kim, Phan Le; Lodder, Cock; Popma, T.J.A.

doi:10.1016/s0304-8853(98)00437-5

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…This explains the slow decay of the magnetization observed for the large applied field where the susceptibility is low and the maximum magnetic viscosity observed around the switching field which corresponds to the susceptibility maxima. Actually, this wellknown behaviour has been reported by other authors [51][52][53]. One should note that there is a weak peak around zero field in each curve for the 3-8 nm particles, which can be attributed to the magnetization relaxation of the fcc particles that have a low switching field.…”

Section: Magnetic Viscosity Coefficientsupporting

confidence: 81%

Effect of thermal fluctuations on magnetization reversal of L1₀ FePt nanoparticles

Rong¹,

Poudyal²,

Liu³

2010

J. Phys. D: Appl. Phys.

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The temperature-dependent switching field, magnetic viscosity and activation volume of L10 FePt nanoparticles with size ranging from 3 to 15 nm have been studied systematically. It is found that the anisotropy constant increases with particle size which is attributed to size-dependent chemical ordering. The temperature dependence of magnetic viscosity and activation volume can be well explained for the 3–8 nm particles by the Stoner–Wohlfarth model incorporating thermal activation, but the model is not suitable for the 15 nm particles. A quantitative analysis of the relation between the switching field and activation volume suggests that the magnetization in the single-crystal 3–8 nm particles reverses via coherent rotation. However, the magnetization reversal in polycrystalline 15 nm particles cannot be well described by coherent rotation although the particle size is much smaller than the single-domain size derived from bulk L10 FePt magnetic material, which may be due to the multiple crystals within each nanoparticle.

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Section: Magnetic Viscosity Coefficientsupporting

confidence: 81%

Effect of thermal fluctuations on magnetization reversal of L1₀ FePt nanoparticles

Rong¹,

Poudyal²,

Liu³

2010

J. Phys. D: Appl. Phys.

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“…T ln(t/τ 0 ) scaling can be also applied to relaxation experiments measuring the acquisition of magnetization of an initially demagnetized system under the application of a magnetic field [41,42,50]. In this kind of experiments, the field modifies the energy barriers that are responsible for the time evolution, as well as the final equilibrium state towards which the system relaxes.…”

Section: Magnetic Relaxationmentioning

confidence: 99%

Finite-size effects in fine particles: magnetic and transport properties

Batlle

Labarta²

2002

J. Phys. D: Appl. Phys.

1,101

539

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Some of the most relevant finite-size and surface effects in the magnetic and transport properties of magnetic fine particles and granular solids are reviewed. The stability of the particle magnetization, superparamagnetic regime and the magnetic relaxation are discussed. New phenomena appearing due to interparticle interactions, such as the collective state and non-equilibrium dynamics, are presented. Surface anisotropy and disorder, spin-wave excitations, as well as the enhancements of the coercive field and particle magnetization are also reviewed. The competition of surface and finite-size effects to settle the magnetic behaviour is addressed. Finally, two of the most relevant phenomena in the transport properties of granular solids are summarized namely, giant magnetoresistance in granular heterogeneous alloys and Coulomb gap in insulating granular solids.

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“…We want to account for the experimental studies on the relaxation of small-particle systems, which essentially measure the acquisition of magnetization of an initially demagnetized sample under the application of a magnetic field. 19,[21][22][23][24] In this kind of ex-periments, the field modifies the energy barriers of the system that are responsible for the time variation of the magnetization, as well as the final state of equilibrium towards which the system relaxes. The fact that usually the magnetic properties of the particles (anisotropy constants, easy-axis directions and volumes) are not uniform in real samples, adds some difficulties to this analysis because the effect of the magnetic field depends on them in a complicated fashion.…”

Section: Introductionmentioning

confidence: 99%

Magnetic field scaling of relaxation curves in small particle systems

Iglesias

Labarta

2002

Journal of Applied Physics

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We study the effects of the magnetic field on the relaxation of the magnetization of small monodomain noninteracting particles with random orientations and distribution of anisotropy constants. Starting from a master equation, we build up an expression for the time dependence of the magnetization which takes into account thermal activation only over barriers separating energy minima, which, in our model, can be computed exactly from analytical expressions. Numerical calculations of the relaxation curves for different distribution widths, and under different magnetic fields H and temperatures T, have been performed. We show how a T ln(t/ 0 ) scaling of the curves, at different T and for a given H, can be carried out after proper normalization of the data to the equilibrium magnetization. The resulting master curves are shown to be closely related to what we call effective energy barrier distributions, which, in our model, can be computed exactly from analytical expressions. The concept of effective distribution serves us as a basis for finding a scaling variable to scale relaxation curves at different H and a given T, thus showing that the field dependence of energy barriers can be also extracted from relaxation measurements.

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Field dependence of magnetic viscosity of CoCrTa in-plane media

Cited by 4 publications

References 6 publications

Effect of thermal fluctuations on magnetization reversal of L1₀ FePt nanoparticles

Effect of thermal fluctuations on magnetization reversal of L1₀ FePt nanoparticles

Finite-size effects in fine particles: magnetic and transport properties

Magnetic field scaling of relaxation curves in small particle systems

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Field dependence of magnetic viscosity of CoCrTa in-plane media

Cited by 4 publications

References 6 publications

Effect of thermal fluctuations on magnetization reversal of L10 FePt nanoparticles

Effect of thermal fluctuations on magnetization reversal of L10 FePt nanoparticles

Finite-size effects in fine particles: magnetic and transport properties

Magnetic field scaling of relaxation curves in small particle systems

Contact Info

Product

Resources

About

Effect of thermal fluctuations on magnetization reversal of L1₀ FePt nanoparticles

Effect of thermal fluctuations on magnetization reversal of L1₀ FePt nanoparticles