Magnetization reversal dynamics, nucleation, pinning, and domain wall propagation in perpendicularly magnetized ultrathin cobalt films: Influence of the Co deposition rate

Belhi, R.; Adjanoh, A. Adjanlété; Vogel, Jan; Ayadi, Mohamed; Abdelmoula, K.

doi:10.1063/1.3506533

Cited by 23 publications

(9 citation statements)

References 29 publications

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“…The magnetic domain density increase is explained by an increase in the density of defects associated with nucleation centers. [41] Defects can also be places of weak anisotropy caused by the thermal effects.…”

Section: Magnetization Reversal Dynamicsmentioning

confidence: 99%

Effects of the Annealing Temperature before Cooling under Magnetic Field on Perpendicular Exchange Coupling in (Pt/Co)5/NiO

Belhi

2021

Physica Status Solidi (a)

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The effects of the annealing temperature before cooling under a magnetic field on the perpendicular exchange coupling in Pt/Co multilayers directly coupled to a NiO layer are studied in the NiO layer thickness range of 1–4 nm. The obtained results reveal that the exchange bias (EB) field and the magnetization reversal process depend on the NiO layer thickness as well as on the annealing temperature. Positive EB fields are observed, especially for 4 nm‐thick NiO layer. However, the values obtained here are low where the largest value is 2.6 mT. This result is attributed to weak antiferromagnetic (AFM) coupling at the Co/NiO interface. These results agree with a blocking temperature of about 300 K. Due to the low blocking temperature, the AFM interfacial spins direction is tilted with respect to the ferromagnet magnetization easy axis. As a consequence, the NiO AFM layer manifests at the Co/NiO interface a weak magnetization perpendicular component giving rise to a weak interfacial exchange coupling which leads to low values.

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Section: Magnetization Reversal Dynamicsmentioning

confidence: 99%

Effects of the Annealing Temperature before Cooling under Magnetic Field on Perpendicular Exchange Coupling in (Pt/Co)5/NiO

Belhi

2021

Physica Status Solidi (a)

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“…Recent experiments showed that magnetic nanoparticles possess either Gaussian distributions f G [3,10,14] or log-normal distributions f LN of sizes [1,11,12]. For small variances, log-normal distributions look similar to Gaussian distributions.…”

Section: B Distributions Of Magnetic Anisotropy Dmentioning

confidence: 99%

“…Recent advances in nanotechnology have allowed synthesis of nanoscale magnetic particles or molecules in various forms, such as in solutions, adsorbed at surfaces, or as powder compacts [1][2][3]. This was motivated by their applications for magnetic storage media [4,5], biosensors [6], and contrast agents in magnetic resonance imaging [7][8][9].…”

mentioning

confidence: 99%

“…Ideally, for a given system, magnetic nanoparticles may have uniform particle sizes and shapes, and molecules may have identical ligand orientations. However, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD) data on magnetic nanoparticles/molecules revealed significant distributions of particle sizes and shapes [1][2][3][10][11][12] or distributions of molecular ligand orientations [13]. In addition, various permanent magnets consist of many nanoscale grains with different sizes and shapes [14].…”

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confidence: 99%

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Effect of the size distribution of magnetic nanoparticles on metastability in magnetization relaxation

Yamamoto

Park

2011

Phys. Rev. B

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We theoretically examine metastability occurring in magnetization relaxation for magnetic nanoparticles with size distributions. An array of magnetic nanoparticles is simulated using a spin S=1 ferromagnetic Blume-Capel model on a square lattice. The particle size distributions give rise to distributions of magnetic anisotropy. Including the distributions, we perform kinetic Monte Carlo simulations of magnetization relaxation at low temperatures for the Blume-Capel model. We compute the average lifetime of the metastable state from the simulations and the absorbing Markov chains method in the low temperature limit. We also carry out similar simulations and calculations for a constant value of magnetic anisotropy for comparison. Our results suggest that the lifetime of the metastable state is determined by the smallest particle for a given system, and that the lifetime with size distributions obeys a modified Arrhenius-like law, where the energy barrier depends on even temperature and standard deviation of the distributions as well as magnetic field and magnetic anisotropy.

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“…They also have various applications including information storage devices [1,2], sensors, and contrast agents in magnetic resonance imaging [3][4][5]. Synthesized magnetic nanoparticles have typically large distributions of size and shape which influence their equilibrium and nonequilibrium properties [6][7][8][9][10][11][12][13]. For example, the size and shape distributions induce distributions in the magnetic anisotropy barrier, magnetization switching or relaxation, and blocking temperature.…”

Section: Introductionmentioning

confidence: 99%

Metastability for the Blume-Capel model with distribution of magnetic anisotropy using different dynamics

Yamamoto

Park

2013

Phys. Rev. E

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We investigate the relaxation time of magnetization or the lifetime of the metastable state for a spin S = 1 square-lattice ferromagnetic Blume-Capel model with distribution of magnetic anisotropy (with small variances), using two different dynamics such as Glauber and phonon-assisted dynamics. At each lattice site, the Blume-Capel model allows three spin projections (+1, 0, −1) and a site-dependent magnetic anisotropy parameter. For each dynamic, we examine the low-temperature lifetime in two dynamic regions with different sizes of the critical droplet and at the boundary between the regions, within the single-droplet regime. We compute the average lifetime of the metastable state for a fixed lattice size, using both kinetic Monte Carlo simulations and the absorbing Markov chains method in the zero-temperature limit. We find that for both dynamics the lifetime obeys a modified Arrhenius-like law, where the energy barrier of the metastable state depends on the temperature and standard deviation of the distribution of magnetic anisotropy for a given field and magnetic anisotropy and that an explicit form of this dependence differs in different dynamic regions for different dynamics. Interestingly, the phonon-assisted dynamic prevents transitions between degenerate states, which results in a large increase in the energy barrier at the region boundary compared to that for the Glauber dynamic. However, the introduction of a small distribution of magnetic anisotropy allows the spin system to relax via lower-energy pathways such that the energy barrier greatly decreases. In addition, for the phonon-assisted dynamic, even the prefactor of the lifetime is substantially reduced for a broad distribution of magnetic anisotropy in both regions considered, in contrast to the Glauber dynamic. Our findings show that overall the phonon-assisted dynamic is more significantly affected by the distribution of magnetic anisotropy than the Glauber dynamic.

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Magnetization reversal dynamics, nucleation, pinning, and domain wall propagation in perpendicularly magnetized ultrathin cobalt films: Influence of the Co deposition rate

Abstract: International audienc

Cited by 23 publications

References 29 publications

Effects of the Annealing Temperature before Cooling under Magnetic Field on Perpendicular Exchange Coupling in (Pt/Co)5/NiO

Effects of the Annealing Temperature before Cooling under Magnetic Field on Perpendicular Exchange Coupling in (Pt/Co)5/NiO

Effect of the size distribution of magnetic nanoparticles on metastability in magnetization relaxation

Metastability for the Blume-Capel model with distribution of magnetic anisotropy using different dynamics

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