Magnetic structure of free cobalt clusters studied with Stern-Gerlach deflection experiments

Payne, Forrest; Jiang, Wei; Emmert, J. W.; Deng, Jun; Bloomfield, L. A.

doi:10.1103/physrevb.75.094431

Cited by 47 publications

(52 citation statements)

References 56 publications

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“…In a size range that is similar to the one considered here, Stern-Gerlach deflection experiments yield total magnetic moments of µ J ≈ 3.0 − 5.5 µ B for neutral iron clusters of 10 to 50 atoms 7,9,11,14,20,43,167 ; µ J ≈ 2.25 − 3.9 µ B for neutral cobalt clusters of 10 to 50 atoms 8,11,14,20,44,45,139,[168][169][170] ; and µ J ≈ 0.8 − 1.3 µ B for neutral nickel clusters of 10 to 15 atoms 10,11,13,14,171 . Even though there is a large scatter in the various Stern-Gerlach data, our average XMCD results for iron (µ J ≈ 3.5 µ B ) and cobalt (µ J ≈ 3.0 µ B ) cluster ions fall well within the range spanned for neutral clusters.…”

Section: F Comparison Of Xmcd Results To Stern-gerlach Experimentsmentioning

confidence: 56%

Spin and orbital magnetic moments of size-selected iron, cobalt, and nickel clusters

et al. 2014

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Spin and orbital magnetic moments of cationic iron, cobalt, and nickel clusters have been determined from x-ray magnetic circular dichroism spectroscopy. In the size regime of n = 10 − 15 atoms, these clusters show strong ferromagnetism with maximized spin magnetic moments of 1 µB per empty 3d state because of completely filled 3d majority spin bands. The only exception is Fewhere an unusually low average spin magnetic moment of 0.73 ± 0.12 µB per unoccupied 3d state is detected; an effect, which is neither observed for Co + 13 nor Ni + 13 . This distinct behavior can be linked to the existence and accessibility of antiferromagnetic, paramagnetic, or nonmagnetic phases in the respective bulk phase diagrams of iron, cobalt, and nickel. Compared to the experimental data, available density functional theory calculations generally seem to underestimate the spin magnetic moments significantly. In all clusters investigated, the orbital magnetic moment is quenched to 5 − 25 % of the atomic value by the reduced symmetry of the crystal field. The magnetic anisotropy energy is well below 65 µeV per atom.

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Section: F Comparison Of Xmcd Results To Stern-gerlach Experimentsmentioning

confidence: 56%

Spin and orbital magnetic moments of size-selected iron, cobalt, and nickel clusters

et al. 2014

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“…[5][6][7] Magnetic organometallic molecules can be formed by bringing together small clusters of transition metal atoms and benzene molecules, such as in the case of cobaltocene and ferrocene.Their magnetic moments have been measured using Stern-Gerlach molecular-beam deflections showing that part of the original magnetization may survive when the number of transition metal centers and ligands are comparable. [8][9][10] More recently, X-ray magnetic circular dichroism spectroscopy (XMCD) has been used to determine independently the orbital-and spin-magnetic moments measured on a trapped and cooled gas of metal cluster ions. [11][12][13] Contrary to the SMMs, where the transition metal centers are surrounded by organic compounds and thus, protecting their magnetic moment, [14][15][16] the transition metal atoms in such organometallic clusters are in close proximity, leading to strong exchange interactions.…”

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confidence: 99%

“…The magnetic properties of Co-Bz complexes have been measured in Stern-Gerlach molecular beam deflection experiments between 60 K and 310 K. 10,21 The magnetic moments per cobalt atom of Co n Bz m clusters with 2 ≤ n ≤ 200, have been found to range from 3.5 µ B to 1.8 µ B and to decrease as the cluster size increases. These magnetic moments were all higher than the bulk cobalt magnetic moment of 1.72 µ B .…”

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Complex magnetic orders in small cobalt–benzene molecules

González

Alonso-Lanza

Delgado

et al. 2017

Phys. Chem. Chem. Phys.

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Organometallic clusters based on transition metal atoms are interesting because possible applications in spintronics and quantum information. In addition to the enhanced magnetism at the nanoscale, the organic ligands may provide a natural shield again unwanted magnetic interactions with the matrices required for applications. Here we show that the organic ligands may lead to non-collinear magnetic order as well as the expected quenching of the magnetic moments. We use different density functional theory (DFT) methods to study the experimentally relevant three cobalt atoms surrounded by benzene rings (Co3Bz3). We found that the benzene rings induce a ground state with non-collinear magnetization, with the magnetic moments localized on the cobalt centers and lying on the plane formed by the three cobalt atoms. We further analyze the magnetism of such a cluster using an anisotropic Heisenberg model where the involved parameters are obtained by a comparison with the DFT results. These results may also explain the recent observation of null magnetic moment of Co3Bz + 3 . Moreover, we propose an additional experimental verification based on electron paramagnetic resonance.

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“…It is discussed in detail in many famous test-books [17,18] on electrodynamics. On the other hand, to the best of our knowledge, the movement of magnetic nanoparticles in an external magnetic field has not been considered so far, although this problem arises naturally in the study of the scattering of magnetic nanoparticles and magnetic nanoclusters [11][12][13] in non -uniform external magnetic field. In this paper we postulate the basic set of equations that describe the motion of a free magnetic nanoparticle both in uniform and non-uniform external magnetic field taking into account the conservation of the total momentum of the nanoparticle, which is the sum of the mechanical and the total spin momentum.…”

Section: Discussionmentioning

confidence: 99%

Magnetic nanoparticle motion in external magnetic field

Usov

Liubimov

2015

Journal of Magnetism and Magnetic Materials

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A set of equations describing the motion of a free magnetic nanoparticle in an external magnetic field in a vacuum, or in a medium with negligibly small friction forces is postulated. The conservation of the total particle momentum, i.e. the sum of the mechanical and the total spin momentum of the nanoparticle is taken into account explicitly. It is shown that for the motion of a nanoparticle in uniform magnetic field there are three different modes of precession of the unit magnetization vector and the director that is parallel the particle easy anisotropy axis. These modes differ significantly in the precession frequency. For the high-frequency mode the director points approximately along the external magnetic field, whereas the frequency and the characteristic relaxation time of the precession of the unit magnetization vector are close to the corresponding values for conventional ferromagnetic resonance. On the other hand, for the low-frequency modes the unit magnetization vector and the director are nearly parallel and rotate in unison around the external magnetic field. The characteristic relaxation time for the low-frequency modes is remarkably long. This means that in a rare assembly of magnetic nanoparticles there is a possibility of additional resonant absorption of the energy of alternating magnetic field at a frequency that is much smaller compared to conventional ferromagnetic resonance frequency. The scattering of a beam of magnetic nanoparticles in a vacuum in a non-uniform external magnetic field is also considered taking into account the precession of the unit magnetization vector and director.

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Magnetic structure of free cobalt clusters studied with Stern-Gerlach deflection experiments

Cited by 47 publications

References 56 publications

Spin and orbital magnetic moments of size-selected iron, cobalt, and nickel clusters

Spin and orbital magnetic moments of size-selected iron, cobalt, and nickel clusters

Complex magnetic orders in small cobalt–benzene molecules

Magnetic nanoparticle motion in external magnetic field

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