Effect of nonuniform perpendicular anisotropy in ferromagnetic resonance spectra in magnetic nanorings

Saavedra, Eduardo; Riveros, A.; Palma, Juan Luis

doi:10.1038/s41598-021-93597-8

Cited by 10 publications

(4 citation statements)

References 35 publications

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“…In this work, we consider Permalloy material with parameters saturation magnetization (M s ) 860 × 10 3 A m −1 , exchange stiffness (A ex ) 13 × 10 −12 J m −1 , and damping coefficient (α) 0.5. These values are comparable with the previous reports [11,33,42]. As depicted in figure 1, an asymmetric ferromagnetic ring has been considered with an external disc diameter (D D ) of 840 nm and introduced a circular void with a diameter (V D ) is 400 nm.…”

Section: Simulation Detailssupporting

confidence: 90%

“…They reported a significant modification in the spin-configurations as the dimension of the ring changes. Moreover, the effect of magneto crystalline anisotropy has also been studied in symmetric Py ring structures by Saavedra et al [33]. Uniaxial anisotropy allows new magnetic spin configurations with various topological magnetic states depending on magnetic anisotropy strength.…”

Section: Introductionmentioning

confidence: 99%

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Effect of void geometry and magnetic anisotropy in controlling the vortex in sub-micron annular Permalloy disc

Palabindela,

Sinha,

Behera

2024

Phys. Scr.

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Ferromagnetic rings, particularly asymmetric Permalloy (Py) rings are recognized as promising configurations for spintronic devices, offering additional degrees of freedom for manipulating magnetic states, especially in vortex configurations. Through micromagnetic simulations, our study explores the impact on magnetization states and spin configuration concerning ring symmetry, aligning with the interest in controlling vortex states for information storage. We initially obtained zero-field spin configurations by varying ring thickness (t), observing a 360° domain wall in rings with t < 12 nm and bi-vortex wall in rings with t ~ 36 nm during magnetization reversal. Notably, an extended stability of the global-vortex state was observed in rings with t > 36 nm, indicating the dominance of global-vortex nucleation in thick asymmetric rings during domain wall movement. We investigate the hysteresis loops and spin configurations by varying the in-plane and out-of-plane anisotropy values. Our findings reveal the presence of multiple vortex cores with different polarities and sense of rotations in the ring for the in-plane anisotropy ~ 30 to ~ 40 kJ/m3. Additionally, a global-vortex with two vortex cores was formed due to demagnetization energy. We analysed the energy profile of stable magnetization states for various t and anisotropy values. Interestingly, the shape of the hysteresis loop changes significantly for the disc containing different shapes of void. Circular and square-shaped geometries suggest that the bi-vortex state is a stable configuration during magnetization reversal in both cases. The study also indicates the stability of the vortex with a square-shaped void geometry up to a sufficiently large field. For the case of triangular-shaped voids, the global-vortex state was favored with even the small fields. The estimated spin canting angles are found to be correlated with the presence of vortex spin configurations. Overall, these results are important for the development of magnetization vortex-based spintronics devices.

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Section: Simulation Detailssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Effect of void geometry and magnetic anisotropy in controlling the vortex in sub-micron annular Permalloy disc

Palabindela,

Sinha,

Behera

2024

Phys. Scr.

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“…Considering the search for new techniques and the improvement of existing ones, in recent years considerable attention has been directed to one-dimensional nanostructured materials [4,5]. This occurs due to their physical properties, mainly in magnetic iron oxide nanoparticles with ring and/or tubular morphology [6,7,8]. A significant property of these particles is the ability to release heat when subjected to an alternating magnetic field [9,10].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Nanorings for Biomedical Applications

et al. 2022

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In this work we investigate the characteristics and feasibility of a new class of magnetic particles that are optimized for possible biological applications as magnetic hyperthermia. These new nanostructures have the nanoring shape, being composed of iron oxides (magnetite or hematite). Such morphology gives the nanoparticles a peculiar magnetic behavior due to their magnetic vortex state. The iron oxide nanorings were obtained using hydrothermal synthesis. X-ray Diffraction confirmed the existence of the desired crystal structure and Scanning Electron Microscopy shows that the magnetite particles had nanometric dimensions with annular morphology (diameter ~250 nm). The nanorings also show intensified magnetic properties and a transition to a vortex state. This study showed that it is possible to obtain magnetic nanorings with properties that can be used in nanotechnological applications (mainly biotechnological ones aimed at the treatment and diagnosis of cancer), in large quantities in a simple synthesis route.

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“…The discovery of fascinating properties of ferromagnetic rings (vortex and onion magnetic states below saturation, specific features of the switching behavior, and peculiarities of magnetic dynamics) [16][17][18][19][20][21] as well as the possibility to control vortex chirality in rings [22,23] make them a promising candidate for usage in magnetoresistive random access memory (MRAM) devices [24,25] and logic circuits [26]. Very recently nanovolcanoes-nanodisks overlaid by nanoringswere proposed as purpose-engineered three-dimensional (3D) architectures for nanomagnonics [27].…”

Section: Introductionmentioning

confidence: 99%

Engineering spin wave spectra in thick Ni80Fe20 rings by using competition between exchange and dipolar fields

et al. 2021

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Control of the spin wave dynamics in nanomagnetic elements is very important for the realization of a broad range of novel magnonic devices. Here we study experimentally the spin wave resonance in thick ferromagnetic rings (100 nm) using perpendicular ferromagnetic resonance spectroscopy. Different from what was observed for the continuous film of the same thickness, or from rings with similar lateral dimensions but with lower thicknesses, the spectra of thick patterned rings show a nonmonotonic dependence of the mode intensity on the resonance field for a fixed frequency. To explain this effect, the theoretical approach by considering the dependence of the mode profiles on both the radial and axial coordinates was developed. It was demonstrated that such unusual behavior is a result of the competition between exchange and dipolar fields acting at the spin excitations in the structure under study. The calculations are in a good agreement with the experimental results.

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Effect of nonuniform perpendicular anisotropy in ferromagnetic resonance spectra in magnetic nanorings

Cited by 10 publications

References 35 publications

Effect of void geometry and magnetic anisotropy in controlling the vortex in sub-micron annular Permalloy disc

Effect of void geometry and magnetic anisotropy in controlling the vortex in sub-micron annular Permalloy disc

Magnetic Nanorings for Biomedical Applications

Engineering spin wave spectra in thick Ni80Fe20 rings by using competition between exchange and dipolar fields

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