Two-dimensional long-range–ordered growth of uniform cobalt nanostructures on a Au(111) vicinal template

Repain, Vincent; Baudot, G.; Ellmer, H.; Rousset, Sylvie

doi:10.1209/epl/i2002-00410-4

Cited by 104 publications

(101 citation statements)

References 22 publications

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“…One of the promising ways to produce arrays of homogeneously distributed monodispersed NCs is to use a bottom-up approach where self-organization growth phenomena on template substrates are used. So far, regular arrays of NCs were successfully assembled using surfaces such as alumina double layers on Ni 3 Al [2,3], vicinal Au(111) surfaces [4,5], reconstructed surfaces [6,7] or h-BN nanomesh [8,9]. Recently, graphene Moiré on close-packed metal surfaces like Pt(111) [10], Rh(111) [11], Ru(0001) [12,13], and Ir(111) [14,15] has been suggested to be a good candidate for the templated growth of clusters arrays.…”

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confidence: 99%

Nucleation and growth of nickel nanoclusters on graphene Moiré on Rh(111)

Sicot

Bouvron

Zander

et al. 2010

Applied Physics Letters

129

132

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Regularly sized Ni nanoclusters (NCs) have been grown on a graphene Moiré on Rh(111). Using scanning tunneling microscopy, we determine that initial growth of Ni at 150 K leads to preferential nucleation of monodispersed NCs at specific sites of the Moiré superstructure. However, a defined long-range ordering of NCs with increasing coverage is not observed. Room temperature Ni deposition leads to the formation of flat triangular-shaped islands which are well-matched to the Moiré registry.

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mentioning

confidence: 99%

Nucleation and growth of nickel nanoclusters on graphene Moiré on Rh(111)

Sicot

Bouvron

Zander

et al. 2010

Applied Physics Letters

129

132

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“…Two-dimensional nanostructures at surfaces are optimally suited to address the origin of anisotropy, and also to explore density limits of non-interacting magnetic bits.The anisotropy imposed by the substrate makes them uniaxial, for example oriented out-of-plane 12 . The size and spatial uniformity achieved by self-assembly techniques 13,14 are comparable to those of colloids. Under ultrahigh vacuum conditions, there is no oxide shell and all constituent atoms are ferromagnetically ordered.…”

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confidence: 82%

The remarkable difference between surface and step atoms in the magnetic anisotropy of two-dimensional nanostructures

et al. 2003

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ARTICLES 546nature materials | VOL 2 | AUGUST 2003 | www.nature.com/naturematerials E xploring the ultimate density limits of magnetic information storage, whether on computer hard disks or in MRAMs (magnetic random access memories), requires elaborate tuning of the preferred (easy) magnetization axis, of the magnetic anisotropy energy, and of the magnetic moment in the units used to store a bit. These units are single-domain particles (with diameter d < 20 nm) where the magnetic moments of all atoms are ferromagnetically aligned 1 to form the overall magnetic moment of the particle M, which is also called the macrospin. The preferred orientations of M, and the anisotropy energy barriers K separating them, are given by the delicate balance between several competing energies. These are the magnetocrystalline bulk anisotropy, its surface and step counterparts, and the shape anisotropy, or demagnetizing energy, resulting from the interaction of M with its own dipolar stray field. Unravelling the anisotropy's origin is far from trivial due to the competition between these energies 2 . This is unfortunate because the anisotropy is one of the key quantities: it defines the stability of the magnetization direction against thermal excitation,and therefore the minimum particle size for which non-volatile information storage may be achieved (at 300 K this requires K ≥ 1.2 eV). A further key parameter is the modulus of M, M defining the dipolar stray field used to read and write, but also mediating interactions between adjacent bits. These interactions are minimized for out-of-plane magnetization, and because the ultimate limit of single-particle bits may only be achieved for uniaxial systems, uniaxial out-of-plane systems are best suited to explore the ultimate density limit of magnetic recording 3,4 . Current studies attempting to identify the origin of magnetic anisotropy mainly deal with two model systems. These are colloids or three-dimensional (3D) nanoparticles, and 2D nanostructures created by molecular-beam epitaxy at single-crystal surfaces. For colloid particles, remarkable progress has been achieved in monodispersity 5 , their self-assembly into 2D superlattices 6,7 and in the accomplished anisotropy energies per constituent atom 8 . Despite their promising properties for applications,3D nanoparticles present several difficulties for tracing back the origin of anisotropy. First, although the magnetism of a single particle can be addressed 9 , it is almost impossible to study the morphology of the very same particle in conjunction with its magnetism. Second, the particles frequently have a few atomic layers of oxide at their surface, which is not ferromagnetic

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“…Figure 20.13d shows a Au(788) surface, where the steps are the energetically favorable {111}-microfacets, which we will call B steps in the following section. Because of elastic repulsions, these steps arrange equidistantly over the entire crystal [188]. The (111)-oriented terraces exhibit a reconstruction similar to the ( √ 3 × 22) reconstruction of Au(111) [189].…”

Section: Heterogeneous Nucleationmentioning

confidence: 99%

“…However, on the vicinal surface, it has a slightly lager period of 7.2 nm, the domain walls run perpendicular to the step edges, and are aligned from terrace to terrace. Nucleation of Co takes place at the crossing of the domain walls and the steps [188,190]. As Figure 20.13d shows, deposition at low T with subsequent annealing creates a well-ordered superlattice of double layer high Co islands with uniform size (HWHM = 20%).…”

Section: Heterogeneous Nucleationmentioning

confidence: 99%

Epitaxial Growth of Thin Films

Brune

2014

Surface and Interface Science

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This chapter gives an introduction to the epitaxial growth of thin films on solid substrates. The term epitaxy refers to the growth of a crystalline layer on (epi) the surface of a crystalline substrate, where the crystallographic orientation of the substrate surface imposes a crystalline order (taxis) onto the thin film. This implies that film elements can be grown, up to a certain thickness, in crystal structures differing from their bulk. If film and substrate have the same crystal lattices, but different lattice constants, the film will be under strain, that is, it will have a slightly different lattice constant than in its own bulk. Both effects, together with the electronic hybridization at the interface, lead to novel properties.One distinguishes homo-and heteroexpitaxy, where the former refers to the growth on one element on a crystal surface of its own and the latter refers to the more general case, where film and substrate materials are different. Note that the first distinguishes itself from crystal growth, as we will see in more detail later.We start this chapter by giving examples from technology, illustrating where thin epitaxial films are used and outlining potential applications that become reality once we are able to grow the respective thin film sequences. We then contrast thin film and crystal growth, respectively, with kinetics and thermodynamics of growth. We introduce the deposition techniques used in epitaxial thin film growth and then discuss the classical thermodynamic approach, which led to the definition of the growth modes. These modes refer to the morphology taken on by a system grown close to thermodynamic equilibrium. Often films are grown far away from equilibrium and their morphology is determined by kinetics, that is, it is the result of the microscopic path taken by the system during growth. This path is determined by the hierarchy of rates of the single atom, cluster or molecular precursor displacements as compared to the deposition rate. Owing to the importance of kinetics, we focus in the rest of the chapter on the kinetic description of growth. In order to simplify the topic, we start with coverages below one atomic layer that is referred to as a monolayer. The first submonolayer part will be on nucleation, followed by a discussion of island shapes that, very much like snowflakes, tell us about the elementary processes that took place during their formation. We then discuss island coarsening, either by evaporation of atoms from their edges, referred to as the Ostwald ripening, or by the diffusion and subsequent coalescence of entire islands, referred to as the

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Two-dimensional long-range–ordered growth of uniform cobalt nanostructures on a Au(111) vicinal template

Cited by 104 publications

References 22 publications

Nucleation and growth of nickel nanoclusters on graphene Moiré on Rh(111)

Nucleation and growth of nickel nanoclusters on graphene Moiré on Rh(111)

The remarkable difference between surface and step atoms in the magnetic anisotropy of two-dimensional nanostructures

Epitaxial Growth of Thin Films

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