Noncollinear magnetism of Cr and Mn nanoclusters on Ni(111): Changing the magnetic configuration atom by atom

Lounis, Samir; Mavropoulos, Phivos; Zeller, R.; Dederichs, P. H.; Blügel, Stefan

doi:10.1103/physrevb.75.174436

Cited by 30 publications

(33 citation statements)

References 30 publications

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“…Nevertheless, the noncollinear magnetism in Cr clusters might still be possible for more excited isomers having larger bond lengths or in the case of clusters deposited on surfaces. 53 Comparing our results with other GGA calculations, we obtain similar results as previous calculations by Wang et al 23 within Gaussian. In fact, they obtain the same ground-state structure, namely, a triangle with the C s symmetry with two atoms forming an AF dimer at a distance of 1.71 Å and the third atom lying at 2.91 and 2.39 Å to the other two atoms and with a total magnetic moment of 6 B .…”

Section: B Trimerssupporting

confidence: 91%

Magnetism of small Cr clusters: Interplay between structure, magnetic order, and electron correlations

et al. 2010

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The magnetic properties of small Cr N clusters ͑N Յ 6͒ are investigated in the framework of densityfunctional theory. The interplay between electron correlations, cluster structure, and magnetic order is quantified by performing fully spin-unrestricted calculations allowing for noncollinear spin arrangements within both the local-spin-density approximation ͑LSDA͒ and the generalized-gradient approximation ͑GGA͒. The possible transition or saddle-point states are identified by determining the vibrational frequencies from diagonalizing the dynamical matrix. In agreement with previous studies, a dimer-based growth pattern is found in all considered low-lying isomers with very short equilibrium bond lengths ͑typically d eq GGA = 1.55-1.65 Å͒ alternating with relative long ones ͑typically d eq GGA = 2.75-2.85 Å͒ in the relaxed geometries. Strong local magnetic moments ជ i are, in general, obtained for the relaxed geometries ͑e.g., ͉ i GGA ͉Ӎ2 B in Cr 4 ͒, which show a collinear magnetic order with antiparallel ͑parallel͒ alignment of the ជ i along the short ͑long͒ bonds. In contrast to the GGA, the LSDA yields vanishing magnetization density in some cases ͉͑ i LSDA ͉ =0 ∀ i for N = 2 and 4͒. Despite quantitative differences, both LSDA and GGA functionals always yield collinear ground-state solutions for the fully relaxed structures. In fact, noncollinear spin arrangements are found only for particular symmetric ͑nondimerized͒ geometries. However, the structures are not local minima and involve considerably large excitation energies. The results clearly indicate that the magnetic frustration, which one would physically expect in compact antiferromagnetic spin systems, is solved by dimerization rather than by noncollinearity of the local moments.

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Section: B Trimerssupporting

confidence: 91%

Magnetism of small Cr clusters: Interplay between structure, magnetic order, and electron correlations

et al. 2010

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“…Different groups report very different results for the same systems (e.g., Refs. [18,19,20]), so that a preference of one or another result is not obvious. Therefore, not so much the size of cluster is a problem in itself, as the organization of a calculation in a way allowing to extract meaningful results, that is, clearly defining structural and magnetic models and carefully 3 analyzing their consequences.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of small Pt-capped Fe, Co, and Ni clusters: A density functional theory study

et al. 2010

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Theoretical studies on M 13 (M = Fe, Co, Ni) and M 13 Pt n (for n = 3, 4, 5, 20) clusters including the spin-orbit coupling are done using density functional theory. The magnetic anisotropy energy (MAE) along with the spin and orbital moments are calculated for M 13 icosahedral clusters. The angle-dependent energy differences are modelled using an extended classical Heisenberg model with local anisotropies. From our studies, the MAE for Jahn-Teller distorted Fe 13 , Mackay distorted Fe 13 and nearly undistorted Co 13 clusters are found to be 322, 60 and 5 µeV/atom, respectively, and are large relative to the corresponding bulk values, (which are 1.4 and 1.3 µeV/atom for bcc Fe and fcc Co, respectively.) However, for Ni 13 (which practically does not show relaxation tendencies), the calculated value of MAE is found to be 0.64 µeV/atom, which is approximately four times smaller compared to the bulk fcc Ni (2.7 µeV/atom). In addition, MAE of the capped cluster (Fe 13 Pt 4 ) is enhanced compared to the uncapped Jahn-Teller distorted Fe 13 cluster.

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“…[2][3][4][5][6][7][8] In the case of nanostructures, for small sizes, recent methodological and technical developments have opened the way to investigate noncollinearity of magnetic nanostructures in the framework of density-functional theory (DFT) [9][10][11][12][13][14][15][16][17] or within the singleband Hubbard models. 18 However, in the case of large complex low-symmetry nanostructures (e.g., deposited or embedded nanoparticles, alloy clusters, extended surface nanostructures) or properties at finite temperature, the involved numerical effort can be quite significant [19][20][21] or unfeasible at present. Therefore, the development of calculation methods and alternative electronic models remains an important theoretical challenge to complement the progress in this field.…”

Section: Introductionmentioning

confidence: 99%

Noncollinear magnetism in transition metal nanostructures: Exchange interaction and local environment effects in free and deposited clusters

et al. 2011

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A self-consistent tight-binding theory of noncollinear magnetism in transition metal nanostructures is presented and applied to free and deposited clusters. The electronic structure is calculated by using a realistic rotational invariant tight-binding Hamiltonian and a real-space recursive expansion of the local Green's functions. For free clusters with sizes N 13, results are given for the ground-state local magnetic moments, magnetic order, and average magnetic moments as a function of the Coulomb exchange integral J and d-band filling. A variety of qualitatively different noncollinear spin arrangement solutions are obtained, which reveals the complex magnetic landscape in transition metal nanostructures. The onset of noncollinear magnetism is discussed by analyzing the stability of the various magnetic solutions. Structural effects are studied by considering representative compact and open geometries. The calculations are compared with available density-functional results. Substrate effects on the noncollinearity of the moments are discussed by considering small Fe clusters deposited on Pt(111). Extensions and limitations of our work are also pointed out.

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Noncollinear magnetism of Cr and Mn nanoclusters on Ni(111): Changing the magnetic configuration atom by atom

Cited by 30 publications

References 30 publications

Magnetism of small Cr clusters: Interplay between structure, magnetic order, and electron correlations

Magnetism of small Cr clusters: Interplay between structure, magnetic order, and electron correlations

Magnetic properties of small Pt-capped Fe, Co, and Ni clusters: A density functional theory study

Noncollinear magnetism in transition metal nanostructures: Exchange interaction and local environment effects in free and deposited clusters

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