Micromagnetic modeling of experimental hysteresis loops for heterogeneous electrodeposited cobalt films

Seymour, Matthew; Wilding, Ian R.; Xu, Bo; Mercer, J. I.; Plumer, M. L.; Poduska, Kristin M.; Yethiraj, Anand; Lierop, J. van

doi:10.1063/1.4793209

Cited by 5 publications

(4 citation statements)

References 23 publications

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“…Such effects on the magnetic properties induced by the deposition of Co on the NPG substrate are in agreement with results obtained in similar systems using different patterned substrates [ 43 , 44 , 45 , 46 ]. Diblock-copolymer porous templates arranged in anti-dots arrays [ 43 ], copper substrates patterned by mechanical scratches [ 46 ], spin-coated colloidal templates [ 45 ] and wrinkled polydimethylsiloxane (PDMS) elastomeric templates [ 44 ] are some published examples of studies using patterned substrates to tune the effective magnetic anisotropy in the Co layer, resulting in variation of its magnetic properties.…”

Section: Resultssupporting

confidence: 91%

Electroless Cobalt Deposition on Dealloyed Nanoporous Gold Substrate: A Versatile Technique to Control Morphological and Magnetic Properties

et al. 2023

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The connection of multidisciplinary and versatile techniques capable of depositing and modeling thin films in multistep complex fabrication processes offers different perspectives and additional degrees of freedom in the realization of patterned magnetic materials whose peculiar physical properties meet the specific needs of several applications. In this work, a fast and cost-effective dealloying process is combined with a fast, low-cost, scalable electroless deposition technique to realize hybrid magnetic heterostructures. The gold nanoporous surface obtained by the dealloying of an Au40Si20Cu28Ag7Pd5 ribbon is used as a nanostructured substrate for the electrodeposition of cobalt. In the first steps of the deposition, the Co atoms fill the gold pores and arrange themselves into a patterned thin film with harder magnetic properties; then they continue their growth into an upper layer with softer magnetic properties. The structural characterization of the hybrid magnetic heterostructures is performed using an X-ray diffraction technique and energy-dispersive X-ray spectroscopy, while the morphology of the samples as a function of the electrodeposition time is characterized by images taken in top and cross-section view using scanning electron microscopy. Then, the structural and morphologic features are correlated with the room-temperature magnetic properties deduced from an alternating-gradient magnetometer’s measurements of the hysteresis loop and first order reversal curves.

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Section: Resultssupporting

confidence: 91%

Electroless Cobalt Deposition on Dealloyed Nanoporous Gold Substrate: A Versatile Technique to Control Morphological and Magnetic Properties

et al. 2023

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“…Further, we assume the particle to have uniaxial anisotropy K = Kk i , where K is the anisotropy constant andk i is the direction of the anisotropy or the easy axis. As the nanoparticles are well separated, it is customary to assume that there is no exchange interaction between them [17,29,40]. The energy of such an assembly therefore includes contributions from the resulting magnetocrystalline anisotropy energy and the long-range dipole-dipole interactions [24,37]:…”

Section: Model and Methodologymentioning

confidence: 99%

Spin morphologies and heat dissipation in spherical assemblies of magnetic nanoparticles

2016

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Aggregates of magnetic nanoparticles (MNPs) exhibit unusual properties due to the interplay of small system size and long-range dipole-dipole interactions. Using the micromagnetic simulation software OOMMF, we study the spin morphologies and heat dissipation in micron-size spherical assemblies of MNPs. In particular, we examine the sensitivity of these properties to the dipolar strength, manipulated by the interparticle separation. As OOMMF is not designed for such a study, we have incorporated a novel scaling protocol for this purpose. We believe that it is essential for all studies where volume fractions are varied. Our main results are as follows: (i) Dense assemblies exhibit strong dipolar effects which yield local magnetic order in the core but not on the surface, where moments are randomly oriented. (ii) The probability distribution of ground-state energy exhibits a long high-energy tail for surface spins in contrast to small tails for the core spins. Consequently, there is a wide variation in the energy of surface spins but not the core spins. (iii) There is strong correlation between ground-state energy and heating properties on application of an oscillating magnetic field h(t) = h o cos 2πf t: the particles in the core heat uniformly, while those on the surface exhibit a wide range from cold to intensely hot. (iv) Specific choices of h o and f yield characteristic spatial heat distributions, e.g., hot surface and cold core, or vice versa. (iv) For all values of h o and f that we consider, heating was maximum at a specific volume fraction. These results are especially relevant in the context of contemporary applications such as hyperthermia and chemotherapy, and also for novel materials such as smart polymer beads and superspin glasses.

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“…Algorithms based on simple Arrhenius-Neel scaling assumptions have been used in the past to extract meaningful results from LLG simulations for MH loops. [2][3][4][5] We recently published an alternative approach based on Kinetic Monte Carlo (KMC) methods which alleviates the problem of having to wait for rare events associated with stochastic processes that involve large energy barriers. 6 The focus of that work was on the simulation of single-layer recording media.…”

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confidence: 99%

Simulations of magnetic hysteresis loops for dual layer recording media

Fal

Plumer

Whitehead

et al. 2013

Applied Physics Letters

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A Kinetic Monte-Carlo algorithm is applied to examine MH loops of dual-layer magnetic recording media at finite temperature and long time scales associated with typical experimental measurements. In contrast with standard micromagnetic simulations, which are limited to the ns-μs time regime, our approach allows for the direct calculation of magnetic configurations over periods from minutes to years. The model is used to fit anisotropy and coupling parameters to experimental data on exchange-coupled composite media which are shown to deviate significantly from standard micromagnetic results. Sensitivities of the loops to anisotropy, inter-layer exchange coupling, temperature, and sweep rate are examined.

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Micromagnetic modeling of experimental hysteresis loops for heterogeneous electrodeposited cobalt films

Cited by 5 publications

References 23 publications

Electroless Cobalt Deposition on Dealloyed Nanoporous Gold Substrate: A Versatile Technique to Control Morphological and Magnetic Properties

Electroless Cobalt Deposition on Dealloyed Nanoporous Gold Substrate: A Versatile Technique to Control Morphological and Magnetic Properties

Spin morphologies and heat dissipation in spherical assemblies of magnetic nanoparticles

Simulations of magnetic hysteresis loops for dual layer recording media

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