Adaptively time stepping the stochastic Landau-Lifshitz-Gilbert equation at nonzero temperature: Implementation and validation in MuMax3

Leliaert, Jonathan; Mulkers, Jeroen; Clercq, Janniek De; Coene, Annelies; Dvornik, Mykola; Waeyenberge, Bartel Van

doi:10.1063/1.5003957

Cited by 104 publications

(59 citation statements)

References 68 publications

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“…where m is the normalized magnetization, g is the Gilbert gyromagnetic ratio, a is the Gilbert damping parameter, H eff is the effective field acting on the local magnetization [27,[41][42][43][44]. m represents the direction of magnetization and is related to magnetization,…”

Section: Methodsmentioning

confidence: 99%

Bilayer skyrmion dynamics on a magnetic anisotropy gradient

2019

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Magnetic skyrmion transport has been primarily based on the use of spin torques which require high current densities and face performance deterioration associated with Joule heating. In this work, we derive an analytical model for energy efficient skyrmion propagation in an antiferromagneticallycoupled bilayer structure using a magnetic anisotropy gradient. The interlayer skyrmion coupling provides a strong restoring force between the skyrmions, which not only prevents annihilation but also increases their forward velocity up to the order of km s -1 . For materials with low Gilbert damping parameter, the interlayer skyrmion coupling force can be amplified up to ten times, with a corresponding increase in velocity. Furthermore, the analytical model also provides insights into the dynamics of skyrmion pinning and relaxation of asymmetric skyrmion pairs in bilayer-coupled skyrmion systems.

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Section: Methodsmentioning

confidence: 99%

Bilayer skyrmion dynamics on a magnetic anisotropy gradient

2019

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“…Thus, it was reasonable to assume the reduced magnetisation value for the tip of the Fe nanorod. Using the freedom of micromagnetic simulations, we also investigated the robustness of our results towards thermal fluctuations, 54 disorder and imperfections, using realistic estimates of their strength. 55 In particular, we have varied the material parameters, the easy axes directions, the nanorod shape, diameter, distance and the regularity of their grid.…”

Section: Methodsmentioning

confidence: 99%

Design of Intense Nanoscale Stray Fields and Gradients at Magnetic Nanorod Interfaces

Ivanov

Leliaert

Crespo

et al. 2019

ACS Appl. Mater. Interfaces

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We explore electrodeposited ordered arrays of Fe, Ni and Co nanorods embedded in anodic alumina membranes as a source of intense magnetic stray field gradients localized at the nanoscale. We perform a multiscale characterization of the stray fields using a combination of experimental methods (Magneto-optical Kerr effect, Virtual Bright Field Differential Phase Contrast Imaging) and micromagnetic simulations, and establish a clear correlation between the stray fields and the magnetic configurations of the nanorods. For uniformly magnetized Fe and Ni wires the field gradients vary following Page 2 of 33 ACS Paragon Plus Environment ACS Applied Materials & Interfaces 3 saturation magnetization of corresponding metal and the diameter of the wires. In the case of Co nanorods, very localized (~10 nm) and intense (> 1T) stray field sources are associated with the cores of magnetic vortexes. Confinement of that strong field at extremely small dimensions leads to exceptionally high field gradients up to 10 8 T/m. These results demonstrate a clear path to design and fine-tune nanoscale magnetic stray field ordered patterns with a broad applicability in key nanotechnologies, such as nanomedicine, nanobiology, nanoplasmonics and sensors.

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“…To numerically integrate these equations, we make use of the software package Vinamax [ 34 ], which we extended with Equation ( 3 ), and which makes use of an efficient algorithm to perform the time-integration of stochastic differential equations [ 35 ].…”

Section: Magnetic Nanoparticle Dynamicsmentioning

confidence: 99%

Simultaneous Coercivity and Size Determination of Magnetic Nanoparticles

Coene

Leliaert

2020

Sensors

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Magnetic nanoparticles are increasingly employed in biomedical applications such as disease detection and tumor treatment. To ensure a safe and efficient operation of these applications, a noninvasive and accurate characterization of the particles is required. In this work, a magnetic characterization technique is presented in which the particles are excited by specific pulsed time-varying magnetic fields. This way, we can selectively excite nanoparticles of a given size so that the resulting measurement gives direct information on the size distribution without the need for any a priori assumptions or complex postprocessing procedures to decompose the measurement signal. This contrasts state-of-the-art magnetic characterization techniques. The possibility to selectively excite certain particle types opens up perspectives in “multicolor” particle imaging, where different particle types need to be imaged independently within one sample. Moreover, the presented methodology allows one to simultaneously determine the size-dependent coercivity of the particles. This is not only a valuable structure–property relation from a fundamental point of view, it is also practically relevant to optimize applications like magnetic particle hyperthermia. We numerically demonstrate that the novel characterization technique can accurately reconstruct several particle size distributions and is able to retrieve the coercivity–size relation of the particles. The developed technique advances current magnetic nanoparticle characterization possibilities and opens up exciting pathways for biomedical applications and particle imaging procedures.

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Adaptively time stepping the stochastic Landau-Lifshitz-Gilbert equation at nonzero temperature: Implementation and validation in MuMax3

Cited by 104 publications

References 68 publications

Bilayer skyrmion dynamics on a magnetic anisotropy gradient

Bilayer skyrmion dynamics on a magnetic anisotropy gradient

Design of Intense Nanoscale Stray Fields and Gradients at Magnetic Nanorod Interfaces

Simultaneous Coercivity and Size Determination of Magnetic Nanoparticles

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