Barium hexaferrite/muscovite heteroepitaxy with mechanically robust perpendicular magnetic anisotropy

AbstractRecent advances in the design and development of magnetic storage devices have led to an enormous interest in materials with perpendicular magnetic anisotropy (PMA) property. The past decade has witnessed a huge growth in the development of flexible devices such as displays, circuit boards, batteries, memories, etc. since they have gradually made an impact on people’s lives. Thus, the integration of PMA materials with flexible substrates can benefit the development of flexible magnetic devices. In this study, we developed a heteroepitaxy of BaFe12O19 (BaM)/muscovite which displays both mechanical flexibility and PMA property. The particular PMA property was characterized by vibrating sample magnetometer, magnetic force microscopy, and x-ray absorption spectroscopy. To quantify the PMA property of the system, the intrinsic magnetic anisotropy energy density of ~2.83 Merg cm−3 was obtained. Furthermore, the heterostructure exhibits robust PMA property against severe mechanical bending. The findings of this study on the BaM/muscovite heteroepitaxy have several important implications for research in next-generation flexible magnetic recording devices and actuators.

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Magnetic anisotropy of graphene quantum dots decorated with a ruthenium adatom

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.4.51 ◽

2013 ◽

Vol 4 ◽

pp. 441-445 ◽

Cited By ~ 1

Author(s):

Igor Beljakov ◽

Velimir Meded ◽

Franz Symalla ◽

Karin Fink ◽

Sam Shallcross ◽

...

Keyword(s):

Magnetic Anisotropy ◽

Density Functional ◽

Magnetic Transition ◽

Graphene Quantum Dots ◽

Magnetic Storage ◽

Magnetic Anisotropy Energy ◽

Magnetization Direction ◽

Storage Devices ◽

Out Of Plane ◽

Graphene Edge

The creation of magnetic storage devices by decoration of a graphene sheet by magnetic transition-metal adatoms, utilizing the high in-plane versus out-of-plane magnetic anisotropy energy (MAE), has recently been proposed. This concept is extended in our density-functional-based modeling study by incorporating the influence of the graphene edge on the MAE. We consider triangular graphene flakes with both armchair and zigzag edges in which a single ruthenium adatom is placed at symmetrically inequivalent positions. Depending on the edge-type, the graphene edge was found to influence the MAE in opposite ways: for the armchair flake the MAE increases close to the edge, while the opposite is true for the zigzag edge. Additionally, in-plane pinning of the magnetization direction perpendicular to the edge itself is observed for the first time.

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Superparamagnetic regular nanopillar-like structures studied by grazing-incidence X-ray scattering: effect of vertical correlation

Journal of Applied Crystallography ◽

10.1107/s1600576714008188 ◽

2014 ◽

Vol 47 (3) ◽

pp. 1065-1076 ◽

Cited By ~ 6

Author(s):

Amitesh Paul ◽

Neelima Paul ◽

Peter Müller-Buschbaum ◽

Andreas Bauer ◽

Peter Böni

Keyword(s):

Three Dimensional ◽

Perpendicular Magnetic Anisotropy ◽

Grazing Incidence ◽

Magnetic Storage ◽

X Ray ◽

Storage Devices ◽

X Ray Scattering ◽

Magnetic Storage Devices ◽

Vertical Correlation ◽

Ray Scattering

Grazing-incidence small-angle X-ray scattering is reported from nanoclusters in superparamagnetic (SPM) polycrystalline Co separated by Au. The self-organization of the Co nanoclusters is in the form of nanopillar-like structures with high perpendicular magnetic anisotropy. A distinct signature of regular near-neighbour ordering is observed, which is commonly observed in patterned nanostructures. The estimated cluster sizes corroborate with those estimated from their magnetic field response. Most significantly, the SPM limit for these clusters can be raised to above room temperature (∼325 K) with an increase in the vertical correlation of the nanopillars. The slow response time of these uniform nanomagnetic grains (with respect to a 10 kHz AC field) suggests their possible usage as potential magnetic storage devices in the form of three-dimensional nanopillars.

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Wear Modeling of Nanometer Thick Protective Coatings

Journal of Tribology ◽

10.1115/1.4033492 ◽

2016 ◽

Vol 139 (2) ◽

Cited By ~ 1

Author(s):

Jungkyu Lee ◽

Youfeng Zhang ◽

Robert M. Crone ◽

Narayanan Ramakrishnan ◽

Andreas A. Polycarpou

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Protective Coatings ◽

Element Model ◽

Disk Surface ◽

Magnetic Storage ◽

Theoretical Frameworks ◽

Storage Devices ◽

Parametric Studies ◽

Magnetic Storage Devices

Use of nanometer thin films has received significant attention in recent years because of their advantages in controlling friction and wear. There have been significant advances in applications such as magnetic storage devices, and there is a need to explore new materials and develop experimental and theoretical frameworks to better understand nanometer thick coating systems, especially wear characteristics. In this work, a finite element model is developed to simulate the sliding wear between the protruded pole tip in a recording head (modeled as submicrometer radius cylinder) and a rigid asperity on the disk surface. Wear is defined as plastically deformed asperity and material yielding. Parametric studies reveal the effect of the cylindrical asperity geometry, material properties, and contact severity on wear. An Archard-type wear model is proposed, where the wear coefficients are directly obtained through curve fitting of the finite element model, without the use of an empirical coefficient. Limitations of such a model are also discussed.

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