Magnetic circular x-ray-dichroism study of Co/Pt(111)

Thiele, Jan-Ulrich; Boeglin, C.; Hricovíni, K.; Chevrier, F.

doi:10.1103/physrevb.53.r11934

Cited by 37 publications

(20 citation statements)

References 29 publications

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“…5(d) it is obvious that attributing the anisotropy of the nanostructures entirely to the surface or interface fails because the green curve is far too broad. In addition, the inferred value of E a = 0.047 ± 0.005 meV/atom is comparable to Co bulk, making difficult any reconciliation with typical thin film values of 0.1-0.2 meV/atom [14,44,45]. The blue curve fits our data much better and associates E a = 0.57 ± 0.05 meV to the perimeter atoms and zero contribution to the surface atoms in the interior of the islands.…”

Section: Quantifying the Contribution Of Perimeter Vs Surface Atoms supporting

confidence: 67%

“…The second point can be at first sight surprising because it contradicts several results on Co/Pt(111) [43,44,[59][60][61][62] and on multilayered Co/Pt [14,45,63] and Co/Pd [64][65][66] films all showing out-of-plane anisotropy. However, three theoretical works show the ideal Co monolayer on Pt(111) [42,67] and Pd(111) [68] to have in-plane anisotropy, the later result having been experimentally proofed [69].…”

Section: Quantifying the Contribution Of Perimeter Vs Surface Atoms contrasting

confidence: 40%

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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: Quantifying the Contribution Of Perimeter Vs Surface Atoms supporting

confidence: 67%

Section: Quantifying the Contribution Of Perimeter Vs Surface Atoms contrasting

confidence: 40%

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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“…[41][42][43][44] or Co/Pt systems. 43,[45][46][47] With spin LEDs integrating out-of-plane magnetic media, Sinsarp et al 48 obtained 1.5% as a lower estimate of the helicity of the light emitted at remanence at room temperature with an FePt/MgO spin injector. Hovel et al 15 have more recently demonstrated a spin injection efficiency of about 3% at remanence using mixed 3d/4f transition metal/rare earth (Fe/Tb) media.…”

Section: Introductionmentioning

confidence: 99%

Spin injection at remanence into III-V spin light-emitting diodes using (Co/Pt) ferromagnetic injectors

et al. 2012

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We have studied the perpendicular magnetic anisotropy of Co/Pt multilayers and the electron spin injection efficiency by optical spectroscopy from a [Co(0.6 nm)/Pt(1 nm)] 4 /Fe(0.3 nm)/MgO perpendicular tunnel spin injector grown on AlGaAs/GaAs semiconductor light-emitting diodes. We observe a 2.5% circular polarization at low temperature close to the magnetic remanence when the 0.3 nm Fe film of the ferromagnetic injector is sufficiently thin to maintain the magnetization out of plane. The acquired squared magnetization cycle is explained by the remaining interlayer exchange coupling existing between Fe and the (Co/Pt) multilayer through Pt or possible perpendicular magnetic anisotropy at the MgO/Fe interface. The corresponding spin polarization of the current is then estimated as 7%, measured by photoluminescence techniques, after the necessary uprenormalization, taking into account the electron spin-flip rate in the quantum well. In contrast, no circular polarization is observed when the thin Fe layer is removed and despite the rather high magnetic polarizability of the 5d 9 electronic open shell of Pt at the interface with MgO. This emphasizes the reduced size of tunneling branching of wave functions at the interface, of the order of the atomic plane unit.

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“…The change of crystal fields and hybridization also affect the DOS. There are many reports supporting enhanced orbital moments for several film systems theoretically [3] and experimentally [4][5][6][7][8], although in some cases reduced orbital moments are also measured [5]. The hybridization effect was emphasized in Co/Cu(100) [5] and Co/Pt [7,8] systems, and the lowering of symmetry was considered important in Co/Cu(100) [4].…”

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confidence: 99%