Magnetic properties of Co/Pt multilayers on self-assembled particle arrays

Ulbrich, T. C.; Assmann, Daniel; Albrecht, Manfred

doi:10.1063/1.3003064

Cited by 26 publications

(18 citation statements)

References 16 publications

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“…Note that for such small nanostructures prepared from particles initially spaced at 180 nm the spherical shape is not maintained and rather semispheres are formed on the Si/SiO 2 substrate [25]. A [Co(0.3 nm)/Pt(0.8 nm)] 12 multilayer stack with an effective perpendicular magnetic anisotropy of 0.3 MJ/m 3 [31] has been deposited by alternating evaporation from pure Co and Pt sources by e-beam evaporation under ultrahigh vacuum conditions at ambient temperature. For integral characterization polar magneto-optical Kerr effect (MOKE) magnetometry with a spot size of about 100 µm was used to investigate magnetic switching (details are given in reference [25]).…”

Section: Resultsmentioning

confidence: 99%

Tuning the properties of magnetic thin films by interaction with periodic nanostructures

Wiedwald¹,

Haering²,

Nau³

et al. 2012

Beilstein J. Nanotechnol.

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SummaryThe most important limitation for a significant increase of the areal storage density in magnetic recording is the superparamagnetic effect. Below a critical grain size of the used CoCrPt exchange-decoupled granular films the information cannot be stored for a reasonable time (typically ten years) due to thermal fluctuations arbitrary flipping of the magnetization direction. An alternative approach that may provide higher storage densities is the use of so-called percolated media, in which defect structures are imprinted in an exchange-coupled magnetic film. Such percolated magnetic films are investigated in the present work. We employ preparation routes that are based on (i) self-assembly of Au nanoparticles and (ii) homogeneous size-reduction of self-assembled polystyrene particles. On such non-close-packed nanostructures thin Fe films or Co/Pt multilayers are grown with in-plane and out-of-plane easy axis of magnetization. The impact of the particles on the magnetic switching behavior is measured by both integral magnetometry and magnetic microscopy techniques. We observe enhanced coercive fields while the switching field distribution is broadened compared to thin-film reference samples. It appears possible to tailor the magnetic domain sizes down to the width of an unperturbed domain wall in a continuous film, and moreover, we observe pinning and nucleation at or close to the imprinted defect structures.

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Section: Resultsmentioning

confidence: 99%

Tuning the properties of magnetic thin films by interaction with periodic nanostructures

Wiedwald¹,

Haering²,

Nau³

et al. 2012

Beilstein J. Nanotechnol.

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show abstract

“…18,19 In this case, although the neighboring nanocaps are interconnected, the interface region possesses paramagnetic properties leading to strong exchange isolation of the neighboring nanocaps in the array. 12,13,16 However, this decoupling mechanism will weaken with increasing number of bilayers, in particular, when the total film thickness is in the range of half the particle diameter.…”

Section: Methodsmentioning

confidence: 98%

“…[12][13][14][15] In these magnetic cap arrays, the magnetic exchange and magnetostatic interaction can be easily tuned by varying the particle diameter as well as the thickness of the deposited magnetic film. 16 For instance, changing the size of the particles allows studying the scaling dependence of the coercive field and switching field distribution ͑SFD͒. In this respect, the main contribution to the SFD is given by the particle size distribution.…”

Section: Introductionmentioning

confidence: 99%

Effect of magnetic coupling on the magnetization reversal in arrays of magnetic nanocaps

et al. 2010

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Magnetic ͓Co/ Pd͔ N multilayers grown on assemblies of spherical polystyrene particles were used as a model system for studying the influence of magnetic coupling on the magnetization reversal by changing the size of the nanoparticles as well as the total thickness of the deposited magnetic film. The coercive field and the switching field distribution are found to be strongly dependent on the size of the nanocaps and on the total thickness of the magnetic layer, indicating a strong influence of the magnetic dipole-dipole interaction on the magnetization reversal of the entire array of nanocaps. Moreover, magnetic viscosity measurements allowed the estimation of the magnetic activation volume representing the effect of thermal activation on the switching process. It was found that the magnetic activation volume is substantially smaller compared to the volume of the nanocap and almost independent of the number of bilayers, and thus the total thickness of the nanocap, supporting an inhomogeneous magnetization reversal process.

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“…Investigation of the local magnetic domain patters using magnetic force microscopy (MFM) at remanence reveals that a single-domain magnetic state is the most favorable state for a Co layer thickness of up to 0.4 nm for all particle sizes; larger Co layer thicknesses results in a multi-domain state in magnetic caps [52].…”

Section: Fig (5)mentioning

confidence: 99%

“…To investigate the influence of the curvature of the surface on the spin-reorientation transition in this novel gradient nanomaterial, a series of [Co(t Co )/Pt(0.8 nm)] 8 multilayers with various individual Co layer thicknesses t Co between 0.2 and 0.8 nm was evaporated at room temperature onto the particle arrays with different particle sizes [52]. The growth of the multilayer was assisted by a 2.9 nm thick Pt buffer layer.…”

Section: [Co/pt(pd)] N Multilayer Stacks On Arrays Of Spherical Partimentioning

confidence: 99%

Magnetic Films on Nanoparticle Arrays

Albrecht¹

2012

TOSURSJ

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Novel properties originating from the combination of magnetism with the reduced dimensionality of nanoobjects are of considerable interest for fundamental science but are also readily used in a wide range of technological applications. To fulfill the demand for larger capacities of storage systems, complex magnetic heterostructures of a nanometer size are envisioned as future magnetic storage media. Here we review recent advances on a novel gradient nanomaterial fabricated by deposition of magnetic thin films onto self-assembled arrays of nonmagnetic spherical particles, resulting in arrays of magnetic caps. Due to the curvature of the particle's surface, magnetic and structural properties of the magnetic thin films differ substantially from their planar counterparts with respect to the equilibrium magnetic domain pattern as well as magnetization reversal behavior. It will be shown that varying the size of the particles as well as the thickness of the deposited layers, the magnetostatic and exchange coupling between the neighboring caps can be systematically modified, providing direct access to the change of fundamental magnetic interactions at the nanoscale. Furthermore, these magnetic cap structures were employed to realize so called bit patterned magnetic media, which is one of the most promising concepts in magnetic data storage to provide areal densities beyond 1 Tbit/inch 2 . In this respect, important aspects regarding the potential application of the magnetic cap structures in magnetic data storage will be addressed.

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Magnetic properties of Co/Pt multilayers on self-assembled particle arrays

Cited by 26 publications

References 16 publications

Tuning the properties of magnetic thin films by interaction with periodic nanostructures

Tuning the properties of magnetic thin films by interaction with periodic nanostructures

Effect of magnetic coupling on the magnetization reversal in arrays of magnetic nanocaps

Magnetic Films on Nanoparticle Arrays

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