Magnetic Nanostructures: 4<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">d</mml:mi></mml:math>Clusters on Ag(001)

Wildberger, K.; Stepanyuk, V. S.; Láng, P.; Zeller, R.; Dederichs, P. H.

doi:10.1103/physrevlett.75.509

Cited by 230 publications

(144 citation statements)

References 27 publications

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“…Small clusters deposited on metal surfaces are predicted to have spin (m S ) and orbital (m L ) magnetic moments in between those of bulk compounds and free atoms [5][6][7], and to exhibit strong magnetic anisotropy with characteristic energies (E a ) of the order of 1-10 meV/atom, i.e., a factor 10 3 larger than bulk ferromagnetic metals [7,8]. In the case of single-domain particles, E a determines the orientation and stability of the magnetization and is thus a crucial parameter for most applications of magnetic materials in modern technology.…”

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

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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: 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

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“…Concomitantly, the interlayer distance decreases about 1% with increasing island size. In order to model the experimental local density of states (LDOS) above the Co islands and link the Co-Co bond relaxations to the electronic structure change, the Korringa-Kohn-Rostoker Green's function method based on density functional theory was used as in previous studies [11,18,19,20]. The method was improved by employing the full potential approximation.…”

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confidence: 99%

Size-Dependent Surface States of Strained Cobalt Nanoislands on Cu(111)

et al. 2007

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Low-temperature scanning tunneling spectroscopy over Co nanoislands on Cu(111) showed that the surface states of the islands vary with their size. Occupied states exhibit a sizeable downward energy shift as the island size decreases. The position of the occupied states also significantly changes across the islands. Atomic-scale simulations and ab inito calculations demonstrate that the driving force for the observed shift is related to size-dependent mesoscopic relaxations in the nanoislands.PACS numbers: 73.20.At, It was recognized quite early that metallic particles exhibit unique properties that differ significantly from their bulk counterparts [1]. Nanoislands grown on metal surfaces, in particular, have been a matter of intense research for decades in view of prospective applications in a vast variety of domains ranging from magnetoelectronics, catalysis, optoelectronics, to data storage technology. The electronic, magnetic and chemical properties of a nanoisland are governed by the size, shape and structure of the island. These, in turn, are profoundly influenced by the lattice mismatch with the metal substrate and, for heteroepitaxial systems, also by the bonding interactions in the island/substrate interface (ligand effects). Metal islands tend to adopt the lattice parameter of the underlying surface [2], and as a consequence the bond lengths between the metal atoms in the supported nanoisland are different than those in the parent metals, resulting in changes due to strain. A theoretical study on homoepitaxial double layer Cu islands on Cu(111) [3], has shown that the strain produces an inhomogeneous distribution of bond lengths over the nanoisland, the average bond length varying with island size. The nanoislands also locally distort the surface and induce a displacement pattern in the substrate which affects the diffusion of atoms and, ultimately, the growth of the nanoislands.Despite these studies, our knowledge of how strain affects the properties of a metallic nanoisland, especially the electronic states, remains very limited. The fundamental problem of the change in energy upon lattice distortion in solids has first been addressed by J. Friedel within a simple model [4], and latter on extended to various problems of lattice contractions at metal surfaces and clusters [5]. On the same lines, it has been shown for thin films that strain effects, along with ligand effects, can cause a shift of the surface d band [6,7,8], resulting in chemical properties that are significantly different from those of the pure overlayer metal. Recently, a modification of electronic states due to a local strain field induced by a nanopattern formation has been observed for Cu(100) covered with N atoms [9].In this Letter, we specifically focus on the interplay between strain-induced structural relaxations and the surface states of Co nanoislands on Cu(111). These nanoislands constitute a reference system that has been extensively investigated by Scanning Tunneling Microscopy/Spectroscopy (STM/STS) [10,11,12,13,14]. By ...

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“…Our ab initio calculations are based on density functional theory and multiple-scattering approach using the Korringa-Kohn-Rostoker Green's function method for low-dimensional systems. 12,20 The main contribution to the interaction energy at large adatom-adatom separations is well approximated by the single-particle energies alone. 12,21,22 We perform calculations of the interaction energies in the framework of the frozen potential approximation and use the Lloyd's formula for calculations of the single-particle energies.…”

Section: Methods Of Calculationmentioning

confidence: 87%

Self-organization of Ce adatoms onAg(111): A kinetic Monte Carlo study

et al. 2006

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One of the most fascinating experimental results in fabrication of artificial nanostructures is the creation of the macroscopically ordered superlattice of Ce adatoms on Ag͑111͒ ͓F. Silly et al., Phys. Rev. Lett. 92, 016101 ͑2004͔͒. Here, performing kinetic Monte Carlo simulations, we study the formation of Ce superlattice at the atomic scale. It is demonstrated that the surface-state mediated long-range interaction between Ce adatoms can lead to their self-assembly into a well ordered structure. The temperature of the substrate and the concentration of Ce adatoms are shown to play a key role in this process.

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Magnetic Nanostructures: 4dClusters on Ag(001)

Cited by 230 publications

References 27 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)

Size-Dependent Surface States of Strained Cobalt Nanoislands on Cu(111)

Self-organization of Ce adatoms onAg(111): A kinetic Monte Carlo study

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