Theoretical study of hyperfine and local magnetic properties of Co and Fe clusters in fcc Ag hosts

Nogueira, Rosete; Petrilli, Helena Maria

doi:10.1103/physrevb.60.4120

Cited by 28 publications

(17 citation statements)

References 27 publications

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“…As concerns the density of states, it was shown earlier for Co clusters on Au(111) that the decrease of the interatomic distances does not alter the general shape of the DOS  the width of the valence band just increases [9]. Importantly, the changes caused by the structural relaxation are all in the same direction (this was observed also for Co clusters embedded in a surface [26] or in the bulk [27]). Therefore, one can expect that including structural relax-ations in our study would lead to quantitative but not qualitative changes and that the systematic trends would be the same.…”

Section: Discussionmentioning

confidence: 65%

Magnetism of free and supported clusters: a comparative study

ipr

MinÃ¡r²,

Ebert³

2009

Open Physics

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Abstract:The presented work investigates the differences in magnetic properties of free and supported clusters via ab-initio calculations. The electronic structure of the clusters was calculated using a spin polarized relativistic multiple-scattering Green's function formalism. We focus on Fe clusters of 2-9 atoms, either free or supported by Ni(001), and on Co clusters of 2-7 atoms, either free or supported by Au(111). For the supported clusters, the spin and orbital magnetic moments depend on the cluster size nearly monotonically, while for the free clusters large quasi-oscillations of magnetic moments with the cluster size were observed. Similarly, for supported clusters, the local spin magnetic moments decrease nearly linearly with increasing coordination number, while for free clusters of the same size range the trend is much more complicated. These findings are consistent with the fact that the spectral distribution function contains much sharper features for free clusters than for supported clusters. PACS IntroductionMetallic clusters present an important class of new materials. Their properties are affected by their finite dimensions and by the high portion of surface atoms. This applies to both free clusters, which can be seen as giant molecules surrounded by vacuum, and supported clusters, which lie on a substrate.Recently, a lot of research has focused on investigating *

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Section: Discussionmentioning

confidence: 65%

Magnetism of free and supported clusters: a comparative study

ipr

MinÃ¡r²,

Ebert³

2009

Open Physics

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“…2 and small aggregates 3 . At the nanometric scale, atomic exchange processes were found to affect the chemical sharpness of interfaces in films and multilayers.…”

Section: Multilayersmentioning

confidence: 99%

Surfactant effect and dissolution of ultrathinFefilms onAg(001)

Terreni¹,

Cossaro

Gonella³

et al. 2004

Phys. Rev. B

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The effects of annealing on the structure of ultra thin Fe films (4 -10 ML) deposited at 150 K on Ag(001) were studied by synchrotron radiation photoelectron diffraction (PED) and x-ray diffraction (XRD). The occurrence of a surfactant-like stage, in which a single layer of Ag covers the Fe film is demonstrated for films of 4-6 ML heated at 500-550 K. Evidence of a stage characterized by the formation of two Ag capping layers is also reported. As the annealing temperature was increased beyond 700 K the surface layers closely resembled the structure of bare Ag(001) with the residual presence of subsurface Fe aggregates. The data illustrate a film dissolution path which is in agreement with recent theoretical models [J. Roussel et al. Phys. Rev. B 60, 13890 (1999)].PACS numbers: 68.35.-p, 68.55.-a The phase immiscibility and the excellent matching between Ag(001) and Fe(001) unit cells (mismatch 0.8 %) make Fe/Ag growth attractive in the field of low dimensionality magnetic systems, such as ultrathin films, 1 multilayers, 2 and small aggregates 3 . At the nanometric scale, atomic exchange processes were found to affect the chemical sharpness of interfaces in films and multilayers.4 Intermixing could be drastically limited at deposition temperatures as low as 140-150 K 4,5,6 at the expense of a poor morphological quality of the film. 7,8The film structural evolution induced by post-growth annealing presents many interesting aspects involving activated atomic exchange processes and affecting magnetic properties.9 Previous experiments, of He and low energy ion scattering on films deposited at 150 K, indicated the formation of a segregated Ag layer upon moderate annealing (550 K). Higher temperatures led to the embedding of Fe into the Ag matrix.10 In those experiments, information on sub-surface layers was attained by ion erosion depth profiling, a destructive technique mainly sensitive to the topmost layer. Many questions remained open about the film structure and morphology evolution during dissolution. Here we address this issue by presenting photoelectron and x-ray diffraction experiments, performed at the ALOISA beam line (ELETTRA, Trieste). PED provides chemically selected data on film structure with an information depth of several layers. It allows to characterize local order in films which are disordered on a long range scale and possesses specific sensitivity to segregation processes.11 Systematic PED measurements have been accompanied with a few XRD rod scans yielding a better sensitivity to the buried interface and the film long range order. The results of this paper allow a comparison with recent models enlightening the dissolution paths of an ultra thin metal film into a different metal, when both subsurface migration of the deposit and phase separation between substrate and deposit are favoured. 17,18Details on the ALOISA system can be found elsewhere.12 The Ag substrate was prepared according to well established procedures.7 Reflection High Energy Electron Diffraction was used to monitor the surfa...

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“…There are scarce systematic studies of the variation of the crystal and magnetic structures with the size of particles embedded in other crystals [7][8][9]. This could be attributed to the difficulty in calculating the electronic structure due to the low symmetry resulting from introducing nanoparticles into the crystalline system.…”

Section: Introductionmentioning

confidence: 96%

The Electronic and Magnetic Properties of FCC Iron Clusters in FCC 4D Metals

et al. 2005

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The electronic and magnetic structures of small FCC iron clusters in FCC Rh, Pd and Ag were calculated using the discrete variational method as a function of cluster size and lattice relaxation. It was found that unrelaxed iron clusters, remain ferromagnetic as the cluster sizes increase, while for relaxed clusters antiferromagnetism develops as the size increases depending on the host metal. For iron in Rh the magnetic structure changes from ferromagnetic to antiferromagnetic for clusters as small as 13 Fe atoms, whereas for Fe in Ag antiferromagnetism is exhibited for clusters of 24 Fe atoms. On the hand, for Fe in Pd the transition from ferromagnetism to antiferromagnetism occurs for clusters as large as 42 Fe atoms. The difference in the magnetic trends of these Fe clusters is related to the electronic properties of the underlying metallic matrix. The local d densities of states, the magnetic moments and hyperfine parameters are calculated in the ferromagnetic and the antiferromagnetic regions. In addition, the average local moment in iron-palladium alloys is calculated and compared to experimental results.Key words magnetic moment · hyperfine fine field · isomer shift · density of states · impurity · cluster · 4d host · iron.

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Theoretical study of hyperfine and local magnetic properties of Co and Fe clusters in fcc Ag hosts

Cited by 28 publications

References 27 publications

Magnetism of free and supported clusters: a comparative study

Magnetism of free and supported clusters: a comparative study

Surfactant effect and dissolution of ultrathinFefilms onAg(001)

The Electronic and Magnetic Properties of FCC Iron Clusters in FCC 4D Metals

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