Wide-Band Electromagnetic Wave Propagation and Resonance in Long Cobalt Nanoprisms

Aziz, Mustafa M.; McKeever, Conor

doi:10.1103/physrevapplied.13.034073

Cited by 6 publications

(22 citation statements)

References 56 publications

(88 reference statements)

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“…27−31 Exchange modes are known to occur at frequencies above the uniform ferromagnetic resonance and provide a potential avenue to achieve impedance matching between magnetic/dielectric layers and to broaden electromagnetic wave absorption at high frequencies. 32,33 However, precise control and prediction of the static and dynamic magnetic properties of multilayered particles remain a challenge due to their dependence on compositional structure, surface coatings, and interlayer coupling. Although most devices exploiting multilayered effects rely on thin films, 34,35 increasing attention has been directed toward three-dimensional magnetic geometries, such as spherical particles, 36 helices, 37,38 torus, 39−41 and the Mobius ring, 42 as they provide new topological mechanisms for controlling magnetic properties at the nanoscale.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Hence, an in-depth understanding of the behavior of core–shell constituents within composite materials is key to achieving technological applications. Magnetic particles have attracted broad attention for a vast number of applications such as impedance matching and antenna miniaturization − in addition to targeted destruction of cancer cells. − In the latter case, it is crucial to achieve repeatability of the magnetization reversal mechanism as this determines the heating performance of the core–shell system during the hysteresis cycle. − In the gigahertz frequency regime, exchange modes have drawn significant interest for the development of efficient microwave absorbers. − Exchange modes are known to occur at frequencies above the uniform ferromagnetic resonance and provide a potential avenue to achieve impedance matching between magnetic/dielectric layers and to broaden electromagnetic wave absorption at high frequencies. , …”

Section: Introductionmentioning

confidence: 99%

“…where i = 1, 2, 3 corresponds to the spherical core, an inner shell, and an outer shell, respectively. The analytical expression for exchange resonance has been shown to accurately predict the resonance absorption peaks of conducting magnetic pillars subject to plane wave excitation, provided that the length of the pillar is comparable to the magnetic skin depth (approximately 50 nm for Co 33 ). Computational Details.…”

mentioning

confidence: 99%

“…To investigate finite magnetic objects, coupled electromagnetic−micromagnetic simulations were performed. 33,59 The electromagnetic fields are computed from Maxwell's curl equations…”

mentioning

confidence: 99%

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Effect of Multilayered Structure on the Static and Dynamic Properties of Magnetic Nanospheres

McKeever

Aziz

2022

ACS Appl. Mater. Interfaces

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The development of flexible and lightweight electromagnetic interference (EMI)-shielding materials and microwave absorbers requires precise control and optimization of core−shell constituents within composite materials. Here, a theoretical model is proposed to predict the static and dynamic properties of multilayered core−shell particles comprised of exchange-coupled layers, as in the case of a spherical iron core coupled to an oxide shell across a spacer layer. The theory of exchange resonance in homogeneous spheres is shown to be a limiting special case of this more general theory. Nucleation of magnetization reversal occurs through either quasi-uniform or curling magnetization processes in core−shell particles, where a purely homogeneous magnetization configuration is forbidden by the multilayered morphology. The energy is minimized through mixing of modes for specific interface conditions, leading to many inhomogeneous solutions, which grow as 2 n with increasing layers, where n represents the number of magnetic layers. The analytical predictions are confirmed using numerical simulations.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

“…To investigate finite magnetic objects, coupled electromagnetic−micromagnetic simulations were performed. 33,59 The electromagnetic fields are computed from Maxwell's curl equations…”

mentioning

confidence: 99%

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Effect of Multilayered Structure on the Static and Dynamic Properties of Magnetic Nanospheres

McKeever

Aziz

2022

ACS Appl. Mater. Interfaces

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“…[ 33 ] Such conventional FDTD‐based methods have been developed for the simulation of various devices and photonic crystals. [ 34–36 ] However, the space and time sample points are located at the half time step and in the integer space grid according to the conventional FDTD algorithm. When employing the above‐mentioned schemes directly to approximate CN algorithms, such conditions will result in the algorithm becoming unstable.…”

Section: Introductionmentioning

confidence: 99%

Implicit Approximate Crank–Nicolson Theory for Anisotropic Ferrite Structure Simulation with Enhanced Absorption

Xie

Jiang

et al. 2021

Advcd Theory and Sims

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To simulate ferrite structures with anisotropic characteristics efficiently, an unconditionally stable implementation is proposed by incorporating the approximate Crank–Nicolson (CN) theory and a complex‐frequency‐shifted perfectly matched layer (CFS‐PML) formulation in the finite‐difference time‐domain lattice. More specifically, the proposed implementation combines the CN approximate factorization splitting procedure with bilinear transformation in the z‐domain within the CFS‐PML regions. To simulate the unique anisotropic characteristic of the ferrite structure, the auxiliary differential equation (ADE) method, which is modified at the integer time step, is introduced during the formulation. Numerical examples are presented to demonstrate the effectiveness and efficiency theoretically and experimentally. According to the results, it can be concluded that the proposed scheme takes full advantage of the approximate CN theory, CFS‐PML formulation, and modified ADE method in terms of the considerable computational accuracy, outstanding absorbing performance, and remarkable efficiency. Moreover, it can be demonstrated that the proposed algorithm can maintain its stability with the dissatisfaction of the Courant–Friedrichs–Lewy condition.

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Electromagnetic wave induced resonance in infinitely long and hollow square cobalt nano-prisms

Aziz

McKeever

2021

J. Phys. D: Appl. Phys.

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Confined metallic ferromagnetic nano-structures are desirable constituents in magnetic composites and devices for applications in telecommunications and electromagnetic wave absorption. Removing the core of these elements or substituting with non-magnetic fillers leads to immediate reduction in their weight and potential for tailoring their magnetic, dielectric and geometrical properties to enable the development of light-weight, high-frequency and efficient composites and devices. However the effect of this geometry change on the electromagnetic wave absorption and magnetic response in these hollow structures is not clear in comparison to their solid counterparts. In this article, electromagnetic wave propagation in long and hollow square cobalt nano-prisms with side lengths of 100 and 500 nm and with different wall thicknesses in the range 25–200 nm is simulated by solving the coupled system of Maxwell’s equations and the Landau–Lifshitz–Gilbert equation using the finite-difference time-domain method. The simulated dynamic magnetisation and power dissipation spectra indicated that the core of the long cobalt prisms can be removed up to wall thicknesses equal to the magnetic skin depth (about 50 nm estimated for cobalt) without significantly impacting electromagnetic wave absorption at the fundamental resonance frequencies. The simulations also revealed prominent higher frequency corner resonance modes in the small 100 nm prism with 25 nm wall thickness, but whose contribution becomes negligible with increasing prism size.

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Wide-Band Electromagnetic Wave Propagation and Resonance in Long Cobalt Nanoprisms

Abstract: The version presented here may differ from the published version. If citing, you are advised to consult the published version for pagination, volume/issue and date of publication

Cited by 6 publications

References 56 publications

Effect of Multilayered Structure on the Static and Dynamic Properties of Magnetic Nanospheres

Effect of Multilayered Structure on the Static and Dynamic Properties of Magnetic Nanospheres

Implicit Approximate Crank–Nicolson Theory for Anisotropic Ferrite Structure Simulation with Enhanced Absorption

Electromagnetic wave induced resonance in infinitely long and hollow square cobalt nano-prisms

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