Perpendicular Magnetic Anisotropy in FePt Patterned Media Employing a CrV Seed Layer

Kim, Hyun-Su; Noh, Jin−Seo; Roh, Jong Wook; Chun, Dong Won; Kim, Sungman; Jung, Sang Hyun; Kang, Hyoungku; Jeong, Won Yong; Lee, Wooyoung

doi:10.1007/s11671-010-9755-2

Cited by 10 publications

(2 citation statements)

References 25 publications

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“…It is interesting to note that H c is larger for smaller particles, suggesting that surface anisotropy plays a major role, as it is greater for particles with a smaller magnetic core. This assumption is based on the already observed anisotropy enhancement of Fe atoms at the Fe/Pt interface, due to high Pt spin–orbit coupling and to symmetry breaking at the interface. , Note that even pure Pt NPs may exhibit ferromagnetism. , However, spontaneous Pt magnetization, if it exists in these NPs, may be disregarded, as its amplitude is orders of magnitude lower than that of spontaneous Fe x O y magnetization.…”

Section: Resultsmentioning

confidence: 99%

Core–Shell Fe–Pt Nanoparticles in Ionic Liquids: Magnetic and Catalytic Properties

Adamski¹,

Qadir²,

Serna

et al. 2018

J. Phys. Chem. C

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The reaction of Fe(CO)5 and Pt2(dba)3 in 1-n-butyl-methylimidazolium tetrafluoroborate (BMIm.BF4), hexafluorophosphate (BMIm.PF6), and bis(trifluoromethanesulfonyl)imide (BMIm.NTf2) under hydrogen affords stable magnetic colloidal core–shell nanoparticles (NPs). The thickness of the Pt shell layer has a direct correlation with the water stability of the anion and increases in the order of PF6 > BF4 > NTf2, yielding the metal compositions Pt4Fe1, Pt3Fe2, and Pt1Fe1, respectively. Magnetic measurements give evidence of a strongly enhanced Pauli paramagnetism of the Pt shell and a partially disordered iron-oxide core with diminished saturation magnetization. The obtained Pauli paramagnetism of the Pt shell is 2 orders of magnitude higher than that of bulk Pt, owing to symmetry breaking at the surface and interface, resulting in a strong increase in the density of states at the Fermi level, and thus to enhanced Pauli susceptibility. Moreover, these ultrasmall NPs showed efficient catalytic activity for the direct production of selective short-chain hydrocarbons (C1–C6) by the Fischer–Tropsch synthesis with efficient conversion (18–34%) and selectivity (69–90%, C2–C4). The selectivity and activity were dependent on the Fe-oxides@Pt particle size. The catalytic activity decreased from 34 to 18% as the NP size increased from 1.7 to 2.5 nm at 15 bar and 300 °C.

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Section: Resultsmentioning

confidence: 99%

Core–Shell Fe–Pt Nanoparticles in Ionic Liquids: Magnetic and Catalytic Properties

Adamski¹,

Qadir²,

Serna

et al. 2018

J. Phys. Chem. C

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“…As the easy magnetization axis of the L1 0 crystal is parallel to the c axis, a (001) orientation is mandatory for practical device applications requiring perpendicular magnetic anistropy. Despite the large lattice misfit of about 9%, MgO(001) substrates [8,9] or seed layers [10][11][12] are commonly employed for epitaxial growth of L1 0 FePt(001). Typically, for film deposition, a substrate temperature higher than 500 • C is required to promote L1 0 order, while lower temperatures result in the chemically disordered fcc (A1) structure.…”

Section: Introductionmentioning

confidence: 99%

L10 -ordered (Fe100−xCrx)Pt thin films: Pha

et al. 2020

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Chemically ordered L1 0 (Fe 100−x Cr x )Pt thin films were expitaxially grown on MgO(001) substrates by magnetron sputter-deposition at 770 • C. In this sample series, Fe was continuously substituted by Cr over the full composition range. The lattice parameter in the [001] growth direction steadily increases from L1 0 -FePt toward L1 0 -CrPt, confirming the incorporation of Cr in the lattice occupying Fe sites. With the observed high degree of chemical ordering and (001) orientation, strong perpendicular magnetic anisotropy is associated, which persists up to a Cr content of x = 20 at. %. Similarly, the coercive field in the easy-axis direction is strongly reduced, which is, however, further attributed to a strong alteration of the film morphology with Cr substitution. The latter changes from a well-separated island microstructure to a more continuous film morphology. In the dilute alloy with low Cr content, isolated Cr magnetic moments couple antiferromagnetically to the ferromagnetic Fe matrix. In this case, all Cr moments are aligned parallel, thus forming a ferrimagnetic FeCrPt system. With increasing Cr concentration, nearest-neighbor Cr-Cr pairs start to appear, thereby increasing magnetic frustration and disorder, which lead to canting of neighboring magnetic moments, as revealed by atomistic spin-model simulations with model parameters based on first principles. At higher Cr concentrations, a frustrated ferrimagnetic order is established. With Cr substitution of up to 20 at. %, no pronounced change in Curie temperature, which is in the range of 700 K, was noticed. But with further addition the Curie temperature drops down substantially even down to room temperature at 47 at. % Cr. Furthermore, x-ray magnetic circular dichroism studies on dilute alloys containing up to 20 at. % of Cr revealed similar spin moments for Fe and Cr in the range between 2.1-2.5 μ B but rather large orbital moments of up to 0.50 ±0.10 μ B for Cr. These results were also compared to ab initio calculations.

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Dense-plasma-driven ultrafast formation of FePt organization on silicon substrate

et al. 2017

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This article demonstrates the removal of organic capping and promotion of long-range 2D organization of chemically synthesized FePt nanoparticles dispersed on Si 100 substrate by means of pulsed H + energetic ion irradiation using a dense plasma focus (DPF) device. The irradiation of energetic H + ions on FePt nanoparticles clearly resulted in enhanced structural and magnetic behaviour of the FePt nanoparticles as a function of plasma focused irradiation shots. Transmission electron microscopy (TEM)/scanning electron microscopy (SEM) images of the FePt nanoparticles clearly show a marked enhancement in average particle size from 2.5 nm for nonirradiated sample to about 28 nm for four plasma focus shots irradiation. The gradual removal of organic capping over chemically synthesized FePt nanoparticles with increasing plasma focus shots exposure is confirmed using Raman spectroscopy. A uniform 2D organization of bimetallic FePt nanoparticles over 1 cm × 1 cm silicon substrate is obtained with three plasma focus shots with better magnetic properties as compared with plasma-untreated FePt nanoparticles.

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Perpendicular Magnetic Anisotropy in FePt Patterned Media Employing a CrV Seed Layer

Cited by 10 publications

References 25 publications

Core–Shell Fe–Pt Nanoparticles in Ionic Liquids: Magnetic and Catalytic Properties

Core–Shell Fe–Pt Nanoparticles in Ionic Liquids: Magnetic and Catalytic Properties

L10 -ordered (Fe100−xCrx)Pt thin films: Pha

Dense-plasma-driven ultrafast formation of FePt organization on silicon substrate

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