Study of the influence of surface anisotropy and lattice structure on the behaviour of a small magnetic cluster

Hernández, Laura; Pinettes, C.

doi:10.1016/j.jmmm.2004.12.042

Cited by 11 publications

(6 citation statements)

References 29 publications

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“…Earlier calculations for small supported Co clusters (up to 10 atoms) suggested that the MAE should not affect the temperature dependence of cluster magnetism significantly [34]. On the other hand, a study of free 13-atom clusters indicated that surface anisotropy could affect the temperature dependence of magnetism for low temperatures (provided that it is sufficiently large) [35]. Calculations relying on a model d-band Hamiltonian suggest that, for our cluster size range, the MAE is larger than in the bulk and that it crucially depends on the cluster size and geometry [36].…”

Section: Discussionmentioning

confidence: 98%

Influence of temperature on the systematics of magnetic moments of free Fe clusters

Šipr¹,

Polesya²,

Minář³

et al. 2007

J. Phys.: Condens. Matter

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We investigate how temperature affects the dependence of the average magnetic momentsμ of clusters on their size and how the magnetic moment profile of an individual cluster varies with temperature T. The focus is on free spherical Fe clusters of 9-89 atoms. The interaction among individual magnetic moments is described by a classical Heisenberg spin Hamiltonian, with exchange coupling constants provided by ab initio calculations. Average magnetic momentsμ for finite T were obtained via Monte Carlo simulations. We found that the exchange coupling depends on the cluster size and on the position of the atom in the cluster in a complex way, with no obvious systematics. The magnetic moment profile of an individual cluster becomes more uniform if T increases. The dependence ofμ on the cluster size, in practice, does not depend on temperature if T is in the range of 0-300 K. Ground-state calculations for T = 0 K should thus be able to describe experiments based on the deflection of a molecular beam in a magnet for T = 0 K.

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Section: Discussionmentioning

confidence: 98%

Influence of temperature on the systematics of magnetic moments of free Fe clusters

Šipr¹,

Polesya²,

Minář³

et al. 2007

J. Phys.: Condens. Matter

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“…A possible reason for this discrepancy could be that spins are not collinear. Although many works on noncollinear spin configurations for transition-metal clusters with d electrons have been carried out [46][47][48][49][50][51], only few have been performed for rare-earth clusters [52][53][54]. As mentioned in the above, a phenomenological model based on the Heisenberg model and RKKY-like interaction considered noncollinear spin configurations [15].…”

Section: Noncollinear Configurationsmentioning

confidence: 99%

Self-consistent determination of HubbardUfor explaining the anomalous magnetism of the Gd13cluster

et al. 2014

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The effective on-site Coulomb interaction (Hubbard U ) is an important parameter for studying strongly correlated systems. While U is determined empirically by fitting to bulk values, its value for a cluster with a finite number of atoms remains uncertain. Here, we choose Gd 13 as a prototypical example of a strongly correlated cluster. Contrary to the well-known results in transition-metal clusters where magnetic moments of clusters are larger than their bulk, in Gd 13 cluster the magnetic moment is smaller than its bulk value. Using density functional theory and the linear response approach, we determine U self-consistently for the cluster and apply it to explain the anomalous magnetic properties of Gd 13 . We demonstrate that the interaction between core and shell atoms of the Gd 13 cluster strongly depends on the Hubbard U . For U = 0 eV magnetism is governed by a direct f-f electron interaction between core and shell atoms, while for U = 5.5 eV it is the indirect Ruderman-Kittel-Kasuya-Yosida interaction that prevails. We also demonstrate that the noncollinear spin arrangement of each atom in the cluster strongly depends on the Hubbard U . Monte Carlo calculations further confirm that magnetic moments decrease with temperature, thus addressing a long-standing disagreement in experimental results.

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“…In the present work we have applied the exact diagonalization method to calculate the properties of clusters with spin-1/2 and 1. We have studied the magnetic and thermodynamic properties of small clusters with the focus on showing the effect of dipolar interaction and uniaxial anisotropy on the magnetization behavior in the presence of magnetic field, the studies of which are still limited in literature [33][34][35] . In addition, the temperature-dependent as well as the ground state spin-spin correlation functions are calculated for these clusters and are compared with respect to the classical case.…”

Section: Introductionmentioning

confidence: 99%

Effect of anisotropy on small magnetic clusters

et al. 2011

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The effect of dipolar interaction and local uniaxial anisotropy on the magnetic response of small spin clusters where spins are located on the vertices of icosahedron, cuboctahedron, tetrahedron and square geometry have been investigated. We consider the ferromagnetic and antiferromagnetic spin-1/2 and spin-1 Heisenberg model with uniaxial anisotropy and dipolar interaction and apply numerical exact diagonalization technique in order to study the influence of frustration and anisotropy on the ground state properties of the spin-clusters. The ground state magnetization, spin-spin correlation and several thermodynamic quantities such as entropy and specific heat are calculated as a function of temperature and magnetic field.Comment: 12 pages, 12 figures, 3 table

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Study of the influence of surface anisotropy and lattice structure on the behaviour of a small magnetic cluster

Cited by 11 publications

References 29 publications

Influence of temperature on the systematics of magnetic moments of free Fe clusters

Influence of temperature on the systematics of magnetic moments of free Fe clusters

Self-consistent determination of HubbardUfor explaining the anomalous magnetism of the Gd13cluster

Effect of anisotropy on small magnetic clusters

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