Magnetic atomistic modelling and simulation of nanocrystalline thin films

Agudelo-Giraldo, J.D.; Ortíz-Álvarez, Hugo Hernán; Restrepo, J.

doi:10.1016/j.spmi.2017.02.032

Cited by 8 publications

(6 citation statements)

References 24 publications

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“…Although the reader could think that the number of simulation parameters is high, it is difficult to limit them by the complexity of the system. Previous works evidenced this [6,7,9], where it has also been concluded that the analysis can be obtained while parameters are kept in the experimental ranges. That is due to the fact that magnetic contributions exert influence in different ways; exchange interaction values are found in the meV; magneto-crystalline anisotropy values are found in the µeV; and dipolar interactions, with D in µeV per pair interaction, increase to medium range due to the number of interactions.…”

Section: Methodsmentioning

confidence: 74%

“…The inset figure shows an xy view, presenting the grain boundaries. The procedure for the sample construction can be observed in a previous work [7]. Periodic boundary conditions (PBC) were implemented in the xy plane, where spin copies are located by means of replicas of the sample; then, the spins are placed at the edges, considering interactions in all directions under the limits of the thickness.…”

Section: Methodsmentioning

confidence: 99%

“…the deformation in the surface and boundary anisotropies. The surface anisotropy equation is presented in (7), in which the effective surface value is given by K S_e f = ε S v i K 1 , where ε S = 0.2, a parameter adjusted according to the change of the perpendicular and in-plane thickness dependence required, which is less than 10 muc [4,8].…”

Section: Methodsmentioning

confidence: 99%

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The Influence of Thickness on the Magnetic Properties of Nanocrystalline Thin Films: A Computational Approach

Agudelo-Giraldo

García

2021

Computation

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A study of the magnetic behaviour of polycrystalline thin films as a function of their thickness is presented in this work. The grain volume was kept approximately constant in the virtual samples. The model includes the exchange interaction, magneto-crystalline anisotropy, surface anisotropy, boundary grain anisotropy, dipolar interaction, and Zeeman effect. The thickness-dependence of the critical temperature, blocking temperature, and irreversibility temperature are presented. Surface anisotropy exerts a great influence at very low thicknesses, producing a monodomain regime. As the thickness increases, the dipolar interaction produces a coupling in-plane of single domains per grain which favours superparamagnetic states. At higher thicknesses, the effects of the in-plane anisotropy produced by dipolar interaction and surface anisotropy decrease dramatically. As a result, the superparamagnetic states present three-dimensional local anisotropies by the grain.

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Section: Methodsmentioning

confidence: 74%

Section: Methodsmentioning

confidence: 99%

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The Influence of Thickness on the Magnetic Properties of Nanocrystalline Thin Films: A Computational Approach

Agudelo-Giraldo

García

2021

Computation

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“…1. The procedure for sample construction was detailed in a previous work where a process of structural relaxation in boundaries was taken into account 7 . Linear dimensions are given in magnetic unit cells (muc) according to magnetic moments positions into the crystal lattice.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Under a reduced set of parameters, previous studies based upon grains size evidenced a range in which correlation between grains is low and phenomena needs to be better studied 32 . Furthermore, based on previous experiences in the simulation area 7,26,32 , it has been concluded that if parameters are adjusted to experimental ranges, how it was done, an analysis of magnetic behaviour of nano-poly-crystalline films with ferromagnetic magnetic cubic cell can be obtained. That is due to the different magnetic contributions acts in ranges of energy well defined.…”

Section: Model Descriptionmentioning

confidence: 99%

Grain boundary anisotropy on nano-polycrystalline magnetic thin films

Agudelo-Giraldo

Restrepo

2020

Sci Rep

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Grain boundaries in polycrystalline thin films with crystallite sizes at nanoscale presents regions characterized by a high degree of local structural disorder. As a consequence, great values of the associated local anisotropies are expected. On this regard, a systematic investigation of the effect of the grain boundary anisotropy on the magnetic properties in such type of nanostructured systems is addressed. For developing this work, a standard Monte Carlo simulation in the framework of classical Heisenberg spins was carried out, with a Hamiltonian involving exchange couplings, dipolar interactions, Zeeman interaction and contributions of cubic magneto-crystalline anisotropy. A quantification of local structural disorder was considered. Results revealed that i) by keeping the same number of grains, different organizations give rise to different spontaneous magnetizations, ii) the critical exponent of the magnetization differs of pure models, which is attributed to the complexity of the lattice and consistent with a distribution of critical temperatures, iii) Boundary anisotropy varies with temperature and its strength are determinant factors for blocking temperatures, and iv) Boundary anisotropy inside in the hysteretic properties where coercive field variations are observed.

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Surface behavior of magnetic phase transitions: A Monte Carlo study

Masrour

Jabar

2018

Applied Surface Science

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Magnetic atomistic modelling and simulation of nanocrystalline thin films

Cited by 8 publications

References 24 publications

The Influence of Thickness on the Magnetic Properties of Nanocrystalline Thin Films: A Computational Approach

The Influence of Thickness on the Magnetic Properties of Nanocrystalline Thin Films: A Computational Approach

Grain boundary anisotropy on nano-polycrystalline magnetic thin films

Surface behavior of magnetic phase transitions: A Monte Carlo study

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