Thermal effect limits in ultrahigh-density magnetic recording

Weller, D.; Möser, Andreas

doi:10.1109/20.809134

Cited by 1,195 publications

(721 citation statements)

References 131 publications

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“…The Co/Pt system was chosen in order to maximize the MAE effects, since hcp-Co presents the largest MAE among 3d ferromagnetic elements (0.045 meV/atom compared to, e.g., 0.005 meV/atom for Fe). In addition, CoPt alloying in the bulk-ordered L1 0 phase results in a MAE increase up to 0.8 meV/Co atom [21], owing to the strong spin-orbit coupling of the Pt 5d states. Fig.…”

Section: Orbital Magnetic Moment and Magnetic Anisotropy Of Single Comentioning

confidence: 99%

“…This effect gives rise to a variety of interesting phenomena, such as enhanced and perpendicular magnetic anisotropy [2,[12][13][14][15][16]19]. Surface-supported nanoparticles offer additional degrees of freedom to tune the magnetic anisotropy by ad-hoc modifications of the particle size, shape, and coupling with the substrate, making nanometer sized systems attractive for basic investigations as well as for miniaturized data storage applications [20][21][22]. In this respect, self-assembled magnetic clusters grown on metal surfaces constitute an ideal system since their size, shape, and composition can be controlled with relative ease while producing them in numbers large enough for investigation with spatially integrating techniques [23,24].…”

Section: Introductionmentioning

confidence: 99%

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Magnetic anisotropy from single atoms to large monodomain islands of Co/Pt(111)

Gambardella

Rusponi

Cren

et al. 2005

Comptes Rendus. Physique

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By studying the magnetic behavior of self-assembled Co islands on a single-crystal metal surface, Pt(111), we show how the magnetic anisotropy evolves from isolated atoms to monolayer islands and films. Single Co adatoms are found to have a giant magnetocrystalline anisotropy energy of E a = 9.3 ± 1.6 meV/atom arising from the combination of partly preserved orbital moments (m L = 1.1 µ B ) and strong spin-orbit coupling induced by the Pt substrate. Combined scanning tunneling microscopy and X-ray magnetic circular dichroism experiments performed for differently sized small two-dimensional Co islands establish a clear connection between E a and m L , both quantities decrease sharply with the lateral coordination of the magnetic atoms. In accordance with this, Kerr magnetometry experiments, again performed in conjunction with scanning tunneling microscopy, reveal that the anisotropy energy of large two-dimensional Co islands is almost entirely determined by the relatively low number of perimeter atoms, having E a = 0.9 ± 0.1 meV/atom. These results confirm theoretical predictions and are of fundamental value the understanding of how the magnetic anisotropy develops in finite-size magnetic particles. Identification of the role of perimeter and surface atoms opens up new opportunities for engineering the anisotropy and the moment of a magnetic nanostructure. RésuméAnisotropie magnétique de l'atome isolé aux îlots monocouches de Co/Pt(111). En étudiant les propriétés magnétiques de particules de Co auto assemblées sur une surface d'orientation (111) d'un monocristal de Pt, nous montrons comment l'anisotropie magnétique évolue de l'atome isolé aux îlots monocouches et aux films ultraminces. Nous trouvons que les atomes de Co isolés adsorbés en surface ont une énergie d'anisotropie magnétocrystalline de E a = 9.3 ± 1.6 meV/atome provenant de la combinaison d'un moment orbital conservé (m L = 1.1 µ B ) et d'un fort couplage spin-orbite induit par le substrat de Pt. Des expériences combinées de microscopie à effet tunnel et de dichroïsme circulaire magnétique à rayons X, effectués sur des îlots de Co de petit taille établissent une connexion claire entre E a et m L , chacune de ces quantités décroissant rapidement avec la coordination latérale des atomes magnétiques. En conformité avec ceci, nous trouvons en employant la magnétométrie par effet Kerr et le microscope à effet tunnel que l'énergie d'anisotropie de grands îlots bidimensionnels de Co est presque entiè-rement déterminée par le nombre relativement faible d'atomes au périmètre, ayant E a = 0.9 ± 0.1 meV/atome. Ces résultats confirment les prédictions théoriques et sont d'un intérêt fondamental pour comprendre comment l'anisotropie magnétique se développe dans les particules magnétiques de taille finie. L'identification du rôle des atomes au périmètre et des atomes de surface ouvre de nouvelles opportunités pour l'ingénierie de l'anisotropie et du moment de nanostructures magnétiques. Pour citer cet article : P. Gambardella et al., C. R. Physique 6 (200...

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Section: Orbital Magnetic Moment and Magnetic Anisotropy Of Single Comentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetic anisotropy from single atoms to large monodomain islands of Co/Pt(111)

Gambardella

Rusponi

Cren

et al. 2005

Comptes Rendus. Physique

View full text Add to dashboard Cite

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“…The presence of two peaks indicates two distinct length scales in this sample. The shorter length scale is close to the average size of polycrystalline grains in these media films as determined by TEM [14]. In analogy with the two peaks observed in scattering from Co/Pt multilayers in ref.…”

Section: Resultsmentioning

confidence: 58%

“…A 5 nm carbon layer tops the structure. The polycrystalline CoPtCr layer has the c axis of the hcp crystal structure in-plane with random in-plane anisotropy, and closely simulates a generation of longitudinal recording media films in which some degree of chemical segregation to the polycrystalline grain boundaries is thought to limit intergrain exchange coupling and account for the recording properties [14,15]. Determining the magnetic and chemical correlation lengths in an asdeposited film using resonant soft x-ray scattering is thus an initial goal of studies of this and related systems.…”

Section: Methodsmentioning

confidence: 99%

Resolving magnetic and chemical correlations in CoPtCr films using soft X-ray resonant scattering

Kortright

Hellwig

Margulies

et al. 2002

Journal of Magnetism and Magnetic Materials

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“…In terms of magnetic recording, increasing areal densities require decreased grain size, which in turn requires increasing values of magnetocrystalline anisotropy energy (MAE) to ensure thermal stability of written information [2]. Currently this is achieved using CoPt alloys with perpendicular anisotropy.…”

Section: Introductionmentioning

confidence: 99%

The effect of a Pt impurity layer on the magnetocrystalline anisotropy of hexagonal close-packed Co: a first-principles study

J.¹,

Palotás²,

Szunyogh³

et al. 2012

J. Phys.: Condens. Matter

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Abstract. In terms of the fully relativistic screened Korringa-Kohn-Rostoker method we investigate the variation in the magnetocrystalline anisotropy energy (MAE) of hexagonal close-packed cobalt with the addition of platinum impurities. In particular, we perform calculations on a bulk cobalt system in which one of the atomic layers contains a fractional, substitutional platinum impurity. Our calculations show that at small concentrations of platinum the MAE is reduced, while at larger concentrations the MAE is enhanced. This change of the MAE can be attributed to an interplay between on-site Pt MAE contributions and induced MAE contributions on the Co sites. The latter ones are subject to pronounced, long-ranged Friedel-oscillations that can lead to significant size effects in the experimental determination of the MAE of nano-sized samples.arXiv:1206.6200v1 [cond-mat.mtrl-sci]

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Thermal effect limits in ultrahigh-density magnetic recording

Cited by 1,195 publications

References 131 publications

Magnetic anisotropy from single atoms to large monodomain islands of Co/Pt(111)

Magnetic anisotropy from single atoms to large monodomain islands of Co/Pt(111)

Resolving magnetic and chemical correlations in CoPtCr films using soft X-ray resonant scattering

The effect of a Pt impurity layer on the magnetocrystalline anisotropy of hexagonal close-packed Co: a first-principles study

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