Micromagnetics and spintronics: models and numerical methods

Abert, Claas

doi:10.1140/epjb/e2019-90599-6

Cited by 103 publications

(62 citation statements)

References 135 publications

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“…According to the SISM, we minimize the total energy of a chosen magnetic region m . For our purposes, we consider the total energy by means of micromagnetics [40] as…”

Section: Appendix A: Micromagnetic Energiesmentioning

confidence: 99%

Dependence of energy barrier reduction on collective excitations in square artificial spin ice: A comprehensive comparison of simulation techniques

et al. 2020

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We perform micromagnetic simulations to study the switching barriers in square artificial spin ice systems consisting of elongated single domain magnetic islands arranged on a square lattice. By considering a double vertex composed of one central island and six nearest neighbor islands, we calculate the energy barriers between two types of double vertices by applying the simplified and improved string method. We investigate by means of micromagnetic simulations the consequences of the neighboring islands, the inhomogeneities in the magnetization of the islands and the reversal mechanisms on the energy barrier by comparing three different approaches with increasing complexity. The micromagnetic models, where the string method is applied, are compared to a method commonly in use, the mean barrier approximation. Our investigations indicate that a proper micromagnetic modeling of the switching process leads to significantly lower energy barriers, by up to 35% compared to the mean-barrier approximation, so decreasing the expected average life time up to seven orders of magnitude. Hereby, we investigate the influence of parallel switching channels and the conceptional approach of using a mean-barrier to calculate the corresponding rates.

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“…According to the SISM, we minimize the total energy of a chosen magnetic region m . For our purposes, we consider the total energy by means of micromagnetics [40] as…”

Section: Appendix A: Micromagnetic Energiesmentioning

confidence: 99%

Dependence of energy barrier reduction on collective excitations in square artificial spin ice: A comprehensive comparison of simulation techniques

et al. 2020

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“…According to the problem setting, the effective field term h eff includes the demagnetization field h demag and the exchange field h ex describing the dipole–dipole interaction and the quantum-mechanical effect of the exchange interaction. In order to simulate the activation of the superparamagnetic label, the effective field is completed by a Zeeman-field contribution h zeeman [ 19 ].

…”

Section: Simulation Methods and Parametersmentioning

confidence: 99%

Micromagnetic Simulations of Submicron Vortex Structures for the Detection of Superparamagnetic Labels

Wetterau

Abert

Suess

et al. 2020

Sensors

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We present a numerical investigation on the detection of superparamagnetic labels using a giant magnetoresistance (GMR) vortex structure. For this purpose, the Landau–Lifshitz–Gilbert equation was solved numerically applying an external z-field for the activation of the superparamagnetic label. Initially, the free layer’s magnetization change due to the stray field of the label is simulated. The electric response of the GMR sensor is calculated by applying a self-consistent spin-diffusion model to the precomputed magnetization configurations. It is shown that the soft-magnetic free layer reacts on the stray field of the label by shifting the magnetic vortex orthogonally to the shift direction of the label. As a consequence, the electric potential of the GMR sensor changes significantly for label shifts parallel or antiparallel to the pinning of the fixed layer. Depending on the label size and its distance to the sensor, the GMR sensor responds, changing the electric potential from 26.6 mV to 28.3 mV.

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“…In typical finite difference approaches 107 where the entire domain is discretized, such an increase in memory allocation will necessarily impose a lower bound on the cell-size (due to the finite amount of RAM), resulting in a poor spectral resolution of the modes. This suggests that at least some novel artificial spin ices may preferentially be modelled by finite element methods 24 , where non-magnetic regions can be managed more efficiently to compute magnetostatic fields 51 , in particular in combination with a boundary element method 108 . In addition, one can envision dedicated schemes including skewed periodic boundary conditions to allow for arbitrary translation vectors and thus equalize the super-cell to the unit-cell.…”

Section: E Modellingmentioning

confidence: 99%

Dynamics of reconfigurable artificial spin ice: Toward magnonic functional materials

2020

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Over the past few years, the study of magnetization dynamics in artificial spin ices has become a vibrant field of study. Artificial spin ices are ensembles of geometrically arranged, interacting magnetic nanoislands, which display frustration by design. These were initially created to mimic the behavior in rare earth pyrochlore materials and to study emergent behavior and frustration using two-dimensional magnetic measurement methods. Recently, it has become clear that it is possible to create artificial spin ices, which can potentially be used as functional materials. In this Perspective, we review the resonant behavior of spin ices (which is in the GHz frequency range), focusing on their potential application as magnonic crystals. In magnonic crystals, spin waves are functionalized for logic applications by means of band structure engineering. While it has been established that artificial spin ices can possess rich mode spectra, the applicability of spin ices to create magnonic crystals hinges upon their reconfigurability. Consequently, we describe recent work aiming to develop techniques and create geometries allowing full reconfigurability of the spin ice magnetic state. We also discuss experimental, theoretical, and numerical methods for determining the spectral response of artificial spin ices, and give an outlook on new directions for reconfigurable spin ices. arXiv:1912.07280v1 [cond-mat.mes-hall]

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Micromagnetics and spintronics: models and numerical methods

Cited by 103 publications

References 135 publications

Dependence of energy barrier reduction on collective excitations in square artificial spin ice: A comprehensive comparison of simulation techniques

Dependence of energy barrier reduction on collective excitations in square artificial spin ice: A comprehensive comparison of simulation techniques

Micromagnetic Simulations of Submicron Vortex Structures for the Detection of Superparamagnetic Labels

Dynamics of reconfigurable artificial spin ice: Toward magnonic functional materials

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