Evidence of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>L</mml:mi><mml:msub><mml:mn>1</mml:mn><mml:mn>0</mml:mn></mml:msub></mml:mrow></mml:math>chemical order in CoPt nanoclusters: Direct observation and magnetic signature

Tournus, Florent; Tamion, Alexandre; Blanc, Nils; Hannour, A.; Bardotti, L.; Prével, B.; Ohresser, P.; Bonet, Edgar; Épicier, Thierry; Dupuis, V.

doi:10.1103/physrevb.77.144411

Cited by 122 publications

(97 citation statements)

References 82 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For 3-nm CoPt nanoparticles embedded in amorphous carbon, an enhanced spin moment relative to the Co nanoparticles of 0.73 μ B has been found by Tournus et al. 22 One should mention here that the magnetic moments of the 3-nm CoPt nanoparticles depend also on the preparation. The spin moment is enhanced to 0.62 μ B by adding a Pt atom to the Co 2 clusters, but the enhancement is clearly below that of the nanoparticles.…”

Section: Resultsmentioning

confidence: 58%

Magnetic properties of small size-selected Co and CoPt clusters on Ni

et al. 2012

View full text Add to dashboard Cite

Size and stoichiometry-dependent magnetic properties of deposited Co and CoPt alloy clusters on a Ni/Cu(100) substrate have been investigated by use of x-ray magnetic circular dichroism spectroscopy. Using sum rules, spin and orbital moments were extracted from the spectra. Spin and orbital moments show a strong size-dependent effect with a tendency for an increase with cluster size, which is in contrast to observations for Co clusters on a Pt(111) surface. Addition of a Pt atom to a Co dimer leads to a doubling of the orbital moment. CoPt clusters show a strong increase in chemical reactivity towards oxidation. The resulting Co n PtO x clusters show a ratio of orbital to spin moment comparable to the pure clusters, however, with a strong suppression of the absolute orbital and spin moments.

show abstract

Section: Resultsmentioning

confidence: 58%

Magnetic properties of small size-selected Co and CoPt clusters on Ni

et al. 2012

View full text Add to dashboard Cite

show abstract

“…14) and, for completeness, the published values for alloyed Co-Pt particles, are included. 16 In all these cases, hybridization effects between 3d Co and 5d metal bands are at the origin of the increase of anisotropy. Thus, alloying Co with W increases the anisotropy with respect to bulk Co where crystalline anisotropy is dominant.…”

Section: Discussionmentioning

confidence: 99%

“…15 Aside from those surface effects described above for the metal-capped Co NPs, the magnetic anisotropy of NP systems may be intrinsic, such as that identified in chemically ordered CoPt NPs. 16 The anisotropy of these particles is correlated with the Co orbital anisotropy, which by hybridization with Pt, and due to the high spin-orbit coupling of the latter, gives rise to an enhanced anisotropy, albeit much smaller than in the bulk CoPt L1 0 phase. Therefore, alloying Co with other metals may be a method of controlling the intrinsic anisotropy, and XMCD the right technique to probe the modification of the average orbital moment.…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic properties of amorphous Co-W alloyed nanoparticles

et al. 2011

View full text Add to dashboard Cite

W-capped Co nanoparticles dispersed in an alumina matrix are studied by means of high-resolution transmission electron microscopy, extended x-ray absorption fine structure, SQUID-based magnetic measurements, dc magnetization, ac magnetic susceptibility, and x-ray magnetic circular dichroism. Results show the formation of amorphous Co-W alloy nanoparticles, the magnetic properties of which are modified by the amount of W or Co present in the samples. The average Co magnetic moment depends on the number of W atoms surrounding it. Co-W particles show superparamagnetic behavior and are described as an array of noninteracting particles with random anisotropy axes and an average moment per particle proportional to the particle volume and to the average Co moment for each alloy composition. Values of the magnetic anisotropy constant of the particles are on the order of 10 6 erg/cm 3 , higher than that of bulk Co. Evidence of short-range ordering within each amorphous particle is found that provides insight of the origin of their magnetic anisotropy.

show abstract

“…Other routes recently used for this purpose consist in producing alloyed particles, so that the intrinsic source of anisotropy is modified [7][8][9][10][11][12]. In this respect, we have recently explored the introduction of high spin-orbit nonmagnetic elements and * aifigueg@gmail.com induce their alloying with Co.…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic properties of granular Co-Pt multilayers with perpendicular magnetic anisotropy

et al. 2014

View full text Add to dashboard Cite

We present a study of granular Co-Pt multilayers by means of high-resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS), SQUID-based magnetic measurements, anomalous Hall effect (AHE), and x-ray magnetic circular dichroism (XMCD). We describe these granular films as composed of particles with a pure cobalt core surrounded by an alloyed Co-Pt interface, embedded in a Pt matrix. The alloy between the Co and Pt in these granular films, prepared by room temperature sputter deposition, results from interdiffusion of the atoms. The presence of this alloy gives rise to a high perpendicular magnetic anisotropy (PMA) in the granular films, as consequence of the anisotropy of the orbital moment in the Co atoms in the alloy, and comparable to that of highly-ordered CoPt L1 0 alloy films. Their magnetic properties are those of ferromagnetically coupled particles, whose coupling is strongly temperature dependent: at low temperatures, the granular sample is ferromagnetic with a high coercive field; at intermediate temperatures the granular film behaves as an amorphous asperomagnet, with a coupling between the grains mediated by the polarized Pt, and at high temperatures, the sample has a superparamagnetic behavior. The coupling/decoupling between the grains in our Co-Pt granular films can be tailored by variation of the amount of Pt in the samples.

show abstract

Evidence ofL10chemical order in CoPt nanoclusters: Direct observation and magnetic signature

Cited by 122 publications

References 82 publications

Magnetic properties of small size-selected Co and CoPt clusters on Ni

Magnetic properties of small size-selected Co and CoPt clusters on Ni

Structural and magnetic properties of amorphous Co-W alloyed nanoparticles

Structural and magnetic properties of granular Co-Pt multilayers with perpendicular magnetic anisotropy

Contact Info

Product

Resources

About