Magnetic moments in chemically ordered mass-selected CoPt and FePt clusters

Dupuis, V.; Khadra, Ghassan; Linas, Sébastien; Hillion, Arnaud; Gragnaniello, Luca; Tamion, Alexandre; Tuaillon-Combes, J.; Bardotti, L.; Tournus, Florent; Otero, Edwige; Ohresser, P.; Рогалев, А.; Wilhelm, F.

doi:10.1016/j.jmmm.2014.12.061

Cited by 25 publications

(15 citation statements)

References 36 publications

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“…19,28,29,37 ). The calculated magnetic moments (M Co = 1.91 µ B , M Pt = 0.40 µ B ) are also in line with previous works 28,29,[38][39][40] . We also note the well-known emergence of an induced moment in Pt, which is due to the hybridization of its 5d orbitals with the exchange splitted 3d orbitals of Co.…”

Section: A Bulk Coptsupporting

confidence: 91%

Giant perpendicular magnetic anisotropy energies in CoPt thin films: impact of reduced dimensionality and imperfections

Brahimi

Bouzar

Lounis

2016

J. Phys.: Condens. Matter

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The impact of reduced dimensionality on the magnetic properties of the tetragonal L10 CoPt alloy is investigated from ab-initio considering several kinds of surface defects. By exploring the dependence of the magnetocrystalline anisotropy energy (MAE) on the thickness of CoPt thin films, we demonstrate the crucial role of the chemical nature of the surface. For instance, Pt-terminated thin films exhibit huge MAEs which can be 1000% larger than those of Co-terminated films. Besides the perfect thin films, we scrutinize the effect of defective surfaces such as stacking faults or anti-sites on the surface layers. Both types of defects reduce considerably the MAE with respect to the one obtained for Pt-terminated thin films. A detailed analysis of the electronic structure of the thin films is provided with a careful comparison to the CoPt bulk case. The behavior of the MAEs is then related to the location of the different virtual bound states utilizing second order perturbation theory.

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Section: A Bulk Coptsupporting

confidence: 91%

Giant perpendicular magnetic anisotropy energies in CoPt thin films: impact of reduced dimensionality and imperfections

Brahimi

Bouzar

Lounis

2016

J. Phys.: Condens. Matter

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Section: Moreover the Particle Shape Is Modeled By Truncated Spheres supporting

confidence: 89%

“…After annealing, the spin moment is lower and is similar to the value found in the literature for FePt nanoparticles [38,66]. However, m L is surprisingly low compared to previous studies [66,72], including our results on 3 nm FePt nanoparticles embedded in carbon matrix (0.18 µ B /at) [38]. m L is very close to the value of L1 0 bulk (0.07 µ B /at [39,71]), which is unexpected, since it is usually assumed that the orbital moment in nano-objects is higher than in bulk due to the broken symmetry.…”

Section: Moreover the Particle Shape Is Modeled By Truncated Spheres supporting

confidence: 88%

Elaboration of Nanomagnet Arrays: Organization and Magnetic Properties of Mass-Selected FePt Nanoparticles Deposited on Epitaxially Grown Graphene on Ir(111)

et al. 2019

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The moiré pattern created by the epitaxy of a graphene sheet on an iridium substrate can be used as a template for the growth of 2D atomic or cluster arrays. We observed for the first time a coherent organization of hard magnetic preformed FePt nanoparticles on the 2D lattice of graphene/Ir(111). Nanoparticles of 2 nm diameter have been mass-selected in gas phase and deposited with a low energy on the hexagonal moiré pattern. Their morphology and organization have been investigated using Grazing Incidence Small Angle X-ray Scattering, while their magnetic properties have been studied by X-ray Magnetic Circular Dichroism, both pointing to a FePt cluster/graphene surface specific interaction. The spatial coherence of the nanoparticles is preserved upon annealing up to 700°C where the hard magnetic phase of FePt is obtained.

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“…For iron-containing bi-metallic nanoparticles, the miscibility between iron and carbon has to be considered. In the size range discussed here (2-6 nm diameter) it has been shown for some elemental combinations (FeRh [39], FePt [40]) that even though carbon interstitials may be formed at the interface between metal particle and matrix, this carbide can be decomposed through heat treatment, leading to pure metallic, chemically ordered FePt and FeRh clusters. In other elemental combinations like FeCo a higher chemical affinity for carbide formation is observed and stable iron carbides are detected [41].…”

Section: Sample Preparationmentioning

confidence: 88%

“…Despite this combination of both properties in the same particle, the iron-silver system in particular does not seem the most adequate candidate system for magneto-plasmonic studies due to the high reactivity of the exposed iron fraction and the resulting reduction of magnetism and the strong phase separation. For other iron-containing nanoparticles, fabricated by the same preparation method (FeRh [39] and FePt [40]), chemically and thermally stable alloy particles have been obtained but here the two metals are miscible in the bulk phase. For iron and gold, with their very limited macroscopic miscibility, a size-induced miscibility was reported in nanoparticles smaller than 10 nm [60] and for different stoichiometries [61].…”

Section: Discussionmentioning

confidence: 99%

Nano-fried-eggs: Structural, optical, and magnetic characterization of physically prepared iron-silver nanoparticles

et al. 2018

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The prospect of combining both magnetic and plasmonic properties in one single nanoparticle promises both valuable insights on the properties of such systems from a fundamental point of view as well as numerous possibilities in technological applications. The combination of two of the most prominent metallic candidates, iron and silver, has, however, presented a lot of experimental difficulties because of their thermodynamic properties impeding miscibility or even coalescence. Here we present the thorough characterization of physically prepared Fe50Ag50 nanoparticles embedded in carbon and silica matrices by electron microscopy, optical spectroscopy, magnetometry and synchrotron-based x-ray spectroscopy. Iron and silver segregate completely into structures resembling fried eggs with a nearly spherical, crystallized silver part surrounded by an amorphous structure of iron carbide or oxide, depending on the environment of the particles. Consequently the particles display both plasmonic absorption corresponding to the silver nanospheres in an oxide environment as well as a reduced but measurable magnetic response. The suitability of such nanoparticles for technological applications is discussed in view of their high chemical reactivity with their environment.

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Magnetic moments in chemically ordered mass-selected CoPt and FePt clusters

Cited by 25 publications

References 36 publications

Giant perpendicular magnetic anisotropy energies in CoPt thin films: impact of reduced dimensionality and imperfections

Giant perpendicular magnetic anisotropy energies in CoPt thin films: impact of reduced dimensionality and imperfections

Elaboration of Nanomagnet Arrays: Organization and Magnetic Properties of Mass-Selected FePt Nanoparticles Deposited on Epitaxially Grown Graphene on Ir(111)

Nano-fried-eggs: Structural, optical, and magnetic characterization of physically prepared iron-silver nanoparticles

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