Small clusters: Magnetic order and magnetic moment

The role of elastic strain for magnetoelectric materials and devices is twofold. It can induce ferroic orders in thin films of otherwise non-ferroic materials. On the other hand, it provides the most exploited coupling mechanism in two-phase magnetoelectric materials and devices today. Complex oxide films (perovskites, spinels) are promising for both routes. The strain control of magnetic order in complex oxide films is a young research field, and few ab initio simulations are available for magnetic order in dependence on lattice parameters and lattice symmetry. Here, an experimental approach for the evaluation of how elastic strain in thin epitaxial films alters their magnetic order is introduced. The magnetic films are grown epitaxially in strain states controlled by buffer layers onto piezoelectric substrates of 0.72Pb(Mg 1/3 Nb 2/3 )O 3 –0.28PbTiO 3 (001). As an example, the strain dependence of the ordered magnetic moment of SrRuO 3 has been investigated. At a tensile strain level of approximately 1%, SrRuO 3 is tetragonal, and biaxial elastic strain induces a pronounced suppression of the ordered magnetic moment. As a second example, a strain-driven transition from a ferromagnetic to a magnetically disordered phase has been observed in epitaxial La 0.8 Sr 0.2 CoO 3 films.

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Magnetic Structures of Some Multiferroics

KnE Materials Science ◽

10.18502/kms.v1i1.575 ◽

2016 ◽

Vol 1 (1) ◽

pp. 135

Author(s):

M.A. Semkin ◽

N.V. Urusova ◽

D.G. Kellerman ◽

A.P. Nosov ◽

S. Lee ◽

...

Keyword(s):

Magnetic Structure ◽

Magnetic Moment ◽

Single Phase ◽

Magnetic Order ◽

Magnetic Structures ◽

Propagation Vector ◽

Ferrimagnetic Structure ◽

Crystal And Magnetic Structures

We studied crystal and magnetic structures of some composite and single-phase multiferroics: (x)MFe2O4 + (1-x)BaTiO3, Ni3-yCoyV2O8, and Bi0.9Ba0.1Fe0.9Ti0.1O3. Composite multiferroics (x)MFe2O4 + (1-x)BaTiO3 with x = (0.2; 0.3; 0.4) and M = (Ni, Co) have ferrimagnetic structure, which is described by the propagation vector k = 0. Oxides Ni3-yCoyV2O8 with y = (0.1; 0.3; 0.5) possess a modulated magnetic structure, described by the vector k = (δ, 0, 0), where δ = 0.283 and 0.348 at 7.4 K for y = 0.1 and 0.5, respectively. In the Bi0.9Ba0.1Fe0.9Ti0.1O3 multiferroic a magnetic order is destroyed at 600 K and the Fe-ion magnetic moment decreases from µ = 3.46(5) μB at 300 K to zero at 600 K.

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Magnetic Order of Fe and Co on Cu (001)

MRS Proceedings ◽

10.1557/proc-313-601 ◽

1993 ◽

Vol 313 ◽

Author(s):

A. Haroun ◽

A. Chouairi ◽

S. Ouannasser ◽

P.J. Jensen ◽

K.H. Bennemann ◽

...

Keyword(s):

Magnetic Moment ◽

Magnetic Order ◽

Tight Binding ◽

Experimental Results ◽

Growth Mode ◽

Initial Growth ◽

Clear Trend ◽

Moment Distribution ◽

Theoretical Predictions

ABSTRACTWe determine the initial growth mode of Co and Fe on Cu (001). In the monolayer range Co and Fe present a clear trend to form clusters on Cu (001). Supposing a perfect epitaxy and fee lattice, the magnetic moment distribution is determined by using a tight binding Hubbard-like Hamiltonian. The influence of the temperature is taken into account in order to compare the theoretical predictions with experimental results.

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Magnetic properties of small ruthenium clusters in fullerene cage — A DFT study

International Journal of Modern Physics B ◽

10.1142/s0217979214501847 ◽

2014 ◽

Vol 28 (27) ◽

pp. 1450184 ◽

Cited By ~ 1

Author(s):

Sunita Srivastava ◽

Akshu Pahuja

Keyword(s):

Magnetic Moment ◽

Density Functional ◽

Magnetic Moments ◽

Fullerene Cage ◽

Gap Formation ◽

Functional Theory ◽

Magnetic Devices ◽

Ruthenium Atom ◽

Small Clusters ◽

Homo Lumo

Encapsulation of small clusters in fullerene cages provides a stable environment for their application in nanoscale functional devices. In this paper, first principles study of Ruthenium as an endohedral dopant in buckminsterfullerene has been carried out using density functional theory. Ruthenium atom has three stable dopant sites inside C 60, with three possible values of magnetic moment (4, 2 and 0 μB). The doping position of Ru atom can be seen to have an effect on HOMO–LUMO gap, formation energy, binding energy and magnetic moment of the fullerene cage. The interaction between Ru and C atoms in different conformations can be explained in terms of Mulliken analysis and density of states analysis. It is also possible to encapsulate more than one Ru atoms in the C 60 cage ( Ru n@ C 60, n = 2–6); encapsulation up to six atoms has been analyzed, after which the process is energetically unfavorable. The geometry of the lowest energy structures, compared to the isolated Ru n clusters, is found to change as a result of encapsulation (e.g., in Ru 3@ C 60 and Ru 5@ C 60). A reduction in magnetic moment of Ru clusters inside fullerene cage as compared to isolated clusters also occurs due to hybridization and confinement effects. The varied magnetic moments of Ru -encapsulated C 60 molecules reveal its applications in molecular magnetic devices and quantum peapods.

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The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100085484 ◽

1991 ◽

Vol 49 ◽

pp. 236-237

Author(s):

J.R. Pfeiffer ◽

J.C. Seagrave ◽

C. Wofsy ◽

J.M. Oliver

Keyword(s):

Mast Cells ◽

Protein A ◽

Scattered Electron ◽

Ige Receptor ◽

Receptor Complexes ◽

Ige Binding ◽

Electron Imaging ◽

Small Clusters ◽

Relationship Of ◽

The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

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Molecular architecture and functions of the neuronal cytoskeleton

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157541 ◽

1990 ◽

Vol 48 (3) ◽

pp. 2-3

Author(s):

Nobutaka Hirokawa

Keyword(s):

Major Elements ◽

Molecular Structures ◽

Organelle Transport ◽

Molecular Architecture ◽

Neuronal Morphogenesis ◽

Microtubule Associated Proteins ◽

Associated Proteins ◽

And Function ◽

Small Clusters

In this symposium I will present our studies about the molecular architecture and function of the cytomatrix of the nerve cells. The nerve cell is a highly polarized cell composed of highly branched dendrites, cell body, and a single long axon along the direction of the impulse propagation. Each part of the neuron takes characteristic shapes for which the cytoskeleton provides the framework. The neuronal cytoskeletons play important roles on neuronal morphogenesis, organelle transport and the synaptic transmission. In the axon neurofilaments (NF) form dense arrays, while microtubules (MT) are arranged as small clusters among the NFs. On the other hand, MTs are distributed uniformly, whereas NFs tend to run solitarily or form small fascicles in the dendrites Quick freeze deep etch electron microscopy revealed various kinds of strands among MTs, NFs and membranous organelles (MO). These structures form major elements of the cytomatrix in the neuron. To investigate molecular nature and function of these filaments first we studied molecular structures of microtubule associated proteins (MAP1A, MAP1B, MAP2, MAP2C and tau), and microtubules reconstituted from MAPs and tubulin in vitro. These MAPs were all fibrous molecules with different length and formed arm like projections from the microtubule surface.

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