Spin and orbital polarized relativistic multiple scattering theory—With applications to Fe, Co, Ni and FexCo1−x

Ebert, H.; Battocletti, M.

doi:10.1016/0038-1098(96)00202-5

Cited by 71 publications

(66 citation statements)

References 30 publications

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“…The error in the diameter is calculated as the standard error in the mean for the measured distribution. Although the data is somewhat scattered-probably due to the particular arrangements of particles for different size distributions-there is a negative correlation between r ls and size (Pearson's r coefficient = −0.71), this tails off for the largest samples close to the bulk value for Fe [16,31]. The m s values are known [26,28] to be close to bulk and to vary little over this size range, therefore we attribute the drop in r ls to a reduction in m l .…”

Section: Size Dependence Of Orbital Momentsmentioning

confidence: 98%

“…This compresses the d-band, enhancing spin (m s ) and therefore orbital (m l ) moment through the spin-orbit (SO) coupling mechanism. The small size can also lead to quantum size effects which increase SO mixing, increasing m l even when m s is saturated [16,17]. XMCD is an element specific technique that allows the contribution of m l and m s to the total moment to be elucidated.…”

Section: Introductionmentioning

confidence: 99%

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Ensemble magnetic behavior of interacting CoFe nanoparticles

et al. 2015

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Ferromagnetic nanoparticles in the 10-14 nm size range are examined for their size and interaction dependent magnetic properties. From X-ray magnetic circular dichroism the orbital-to-spin magnetic moment ratio is determined and found to decrease significantly with particle size. This is in accordance with previous complementary studies on smaller particles and highlights the difficulty of fitting to a simple core-shell model. Vibrating sample magnetometry experiments on samples with more than 1000 particles per square micron show a wide distribution of blocking temperatures from 50 to greater than 650 K. This is attributed to the dipole-dipole magnetic coupling forces between particles. The blocking temperatures show an unexpected negative correlation with increasing particle density.

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Section: Size Dependence Of Orbital Momentsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Ensemble magnetic behavior of interacting CoFe nanoparticles

et al. 2015

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“…The orbital moments calculated in the relativistic LDA formalism are usually about 30%-50% smaller than the corresponding experimental values due to the neglect of correlation effects. Brooks has suggested a way to improve this shortcoming by an additional heuristic term in the Hamiltonian [11,12], which we include in our calculations for the d valence electrons in the form suggested by Ebert [13]:…”

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confidence: 99%

Strongly Enhanced Orbital Moments and Anisotropies of Adatoms on the Ag(001) Surface

et al. 2001

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We present ab initio calculations for orbital moments and anisotropy energies of 3d and 5d adatoms on the Ag(001) surface, based on density functional theory, including Brooks' orbital polarization (OP) term, and applying a fully relativistic Korringa-Kohn-Rostoker -Green's function method. In general, we find unusually large orbital moments and anisotropy energies, e.g., in the 3d series, 2.57m B and 174 meV for Co, and, in the 5d series, 1.78m B and 142 meV for Os. These magnetic properties are determined mainly by the OP and even exist without spin-orbit coupling. DOI: 10.1103/PhysRevLett.86.2146 The interest in surface magnetism is primarily caused by the enhancement of the spin moments at surfaces being driven by the reduced coordination. A typical example for this effect is iron, for which the bulk moment (2.15m B ) is enhanced at the (001) [6]. Here the 4d and 5d atoms, being nonmagnetic as impurities in the bulk, show as adatoms very large local moments comparable with the free atom values. Sizable moments also survive when these atoms are incorporated into the first layer.In contrast to the spin magnetism, the orbital magnetism in solids has its origin in the spin-orbit interaction and is closely connected with the magnetocrystalline anisotropy, with magneto-optical effects and magnetic x-ray dichroism. In this paper we address the enhancement of orbital moments at surfaces. It is well known that the orbital moments are "quenched" in the bulk, i.e., strongly suppressed by the crystal field splitting, the strong hybridization with the neighboring atoms, respectively. Thus, calculations yield very small orbital moments: 0.049m B , 0.075m B , and 0.042m B for bcc Fe, hcp Co, and fcc Ni [0.082m B , 0.123m B , and 0.058m B if Brooks' orbital polarization (OP) is included] [7]. At surfaces ab initio calculations show that also the orbital moments are enhanced, to e.g., a value of 0.090m B at the hcp Co(0001) surface (0.158m B if Brooks' OP is included) [7,8]. Even larger orbital moments are obtained for the 3d monolayers, e.g., 0.121m B for a Co monolayer on Cu(100) (0.261m B including OP) [7,9]. Thus, at surfaces the quenching of the orbital moments is less pronounced due to the reduced hybridization. However, it is important to realize that these enhanced orbital moments are still an order of magnitude smaller than the corresponding free atom values, as given by Hund's second rule. Thus, the orbital moments are to a large extent also quenched at the surface, as it seems to be the general rule in metallic environments.However, this rule can have exceptions. Riegel and co-workers [10] have already shown that Fe impurities, being injected into alkali metals, show hyperfine properties which indicate very large orbital moments, probably the full atomic values. The low and more or less constant electron density of the alkali hosts is responsible for this behavior. Here we will predict by density functional calculations that single 3d and 5d transition metal impurities on the Ag(001) surface can have very large or...

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“…To understand the electronic structure of the non stoichiometric compounds, firstprinciples calculations were performed using the KKR (Korringa-Kohn-Rostoker) Green's function method as implemented in the Munich SPR-KKR (spin-polarized relativistic) package 48,49 . The chemical disorder is treated by the coherent potential approximation (CPA) 50,51 .…”

Section: Calculations Of the Electronic Structurementioning

confidence: 99%