Magnetisation reversal in Ising ferromagnet by thermal and field gradients

Datta, Ranajay; Acharyya, Muktish; Dhar, A.

doi:10.1016/j.heliyon.2018.e00892

Cited by 10 publications

(6 citation statements)

References 15 publications

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“…Very recently, the magnetisation reversal in Ising ferromagnet by a field having spatial gradient was studied [18]. In another work same study has been done when both field and thermal gradient are present in the system and a marginal competition between them has been reported [19]. So far as the knowledge of the authors is concerned, the study of magnetisation reversal has not yet been carried out for randomly quenched (site dependent but time independent) magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Effects of random fields on the reversal of magnetisation of Ising ferromagnet

Naskar

Acharyya

2020

Physica A: Statistical Mechanics and its Applications

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We study the reversal time of magnetisation in two dimensional Ising ferromagnet in the presence of externally applied uniform magnetic field using Monte Carlo simulation based on Metropolis single spin flip algorithm. Then we investigate the change in reversal time in presence of quenched random field in addition to the uniform (over the space) magnetic field. We report the results of distribution of reversal times of different samples in the presence of three different types of the distributions (namely, uniform, bimodal and normal) of random fields and compared the results with those obtained for uniform field only. We have observed that the reversal time decreases in presence of any kind (of distribution) of the random fields. Dependence of reversal times on temperature and different widths of random fields are also reported. We also checked whether the system obey Becker-Döring theory of classical nucleation in presence of random field and tried to investigate the range of the width of the distribution of random field, beyond which the system seems to fail to behave as prescribed by Becker-Döring theory.

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Section: Introductionmentioning

confidence: 99%

Effects of random fields on the reversal of magnetisation of Ising ferromagnet

Naskar

Acharyya

2020

Physica A: Statistical Mechanics and its Applications

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“…As a result, there would be a competitive scenario regarding reversal influenced by both field and anisotropy simultaneously. To explore this competitive behaviour quantitatively, a competition factor [14] can be defined as,…”

Section: Simulational Resultsmentioning

confidence: 99%

“…where R i is the spin at i-th lattice site of a reference lattice [14] whose left half sites are filled with spin '-1' only and the right half by spin '+1'. σ i is the spin at i-th lattice site of the main lattice we are studying.…”

Section: Simulational Resultsmentioning

confidence: 99%

“…The statistical behaviours of magnetisation reversal was studied [12] in random field Ising model by Monte Carlo simulation to investigate the role of quenched impurity in the switching phenomena. The reversal with nonuniform (over space) magnetic field was also investigated [13] and a marginally competitive line was drawn [14] in the plane formed by the gradient of field and the gradient of temperature. The switching of magnetisation was investigated in Ising ferromagnets by periodic pulsed [15,16] magnetic field and a time dependent field like spreading Gaussian [17].…”

Section: Introductionmentioning

confidence: 99%

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Metastability in graded and step like variation of field and anisotropy of the Blume-Capel ferromagnet

Naskar,

Acharyya

2020

Preprint

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The metastable behaviour of two dimensional anisotropic Blume-Capel ferromagnet under the influence of graded and stepped magnetic field has been investigated by extensive Monte Carlo simulation using Metropolis single spin flip algorithm. Starting from the initial perfectly ordered state, reversal of magnetisation has been studied in presence of the field. Metastable lifetime or the reversal time of magnetisation for the system having uniform anisotropy and in the presence of both graded and stepped field has been studied. Also the same has been explored for a graded and stepped anisotropic system in presence of a uniform field. Finite size effect is analyzed for the variation of reversal time with gradient of field (G h ) and a scaling relation) is found out. Spatial variation of density profile for the projection states (i.e., +1, 0 and -1) has also been studied at the moment of reversal of magnetisation. The spatial variation of the number of spin flips per site is studied. Motion of the interface (or domain wall) with the gradient of field and gradient of anisotropy are investigated and are found to follow the hyperbolic tangent like behaviours in both cases. Since, both the anisotropy and the applied field have significant impact on the metastable lifetime, an interesting competitive scenario is observed for a graded anisotropic system in graded field and a stepped anisotropic system in stepped field. A line of marginal competition has been found out for both the cases separating the regions of field dominated reversal and anisotropy dominated reversal.

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“…The effects of randomly quenched disorder (random field) on the reversal has been reported [13] recently in Ising ferromagnets. The effects of gradient of field [14] and gradient of temperature [15] in the reversal of Ising ferromagnet has also been studied by Monte Carlo (MC) simulation. Recently, the role of anisotropy [16]and its gradient [17] has been studied in the Blume-Capel (BC) ferromagnets.…”

Section: Introductionmentioning

confidence: 99%

Competitive metastable behaviours of surface and bulk in Ising ferromagnet

Naskar,

Acharyya

2021

Preprint

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The reversal of magnetisation has been studied in a three dimensional Ising ferromagnet by Monte Carlo simulation with Metropolis single spin flip random updating scheme. The outer layers are considered as surface. The surface interacts with core with a relative ferromagnetic interaction strength. The times of reversal of the surface and that of bulk were found to be different for different values of relative interaction strength. For weaker relative strength surface reversal was found to be faster than that of bulk and vice versa for stronger relative interaction strength. A critical value (R c ) of relative interaction strength provides same time of reversal of surface and bulk. This critical relative interaction strength was found to be a function of the temperature (T ) and applied magnetic field (h). The scaling relation R c ∼ h −β f (T h α ), where, α = 0.23 ± 0.01 and β − 0.06 ± 0.01, was found numerically by the method of data collapse. The metastable volume fractions, for both surface and bulk, were found to follow the Avrami's law. The critical relative interaction strength (R c ) has been found to decrease in an exponential (e bx −1.5 ) manner with the system size (L).

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Magnetisation reversal in Ising ferromagnet by thermal and field gradients

Cited by 10 publications

References 15 publications

Effects of random fields on the reversal of magnetisation of Ising ferromagnet

Effects of random fields on the reversal of magnetisation of Ising ferromagnet

Metastability in graded and step like variation of field and anisotropy of the Blume-Capel ferromagnet

Competitive metastable behaviours of surface and bulk in Ising ferromagnet

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