Electronic structure and spectroscopic properties of thulium monochalcogenides

Lebègue, Sébastien; Santi, Gilles; Svane, A.; Bengone, O.; Katsnelson, M. I.; Lichtenstein, A. I.; Eriksson, Olle

doi:10.1103/physrevb.72.245102

Cited by 37 publications

(34 citation statements)

References 43 publications

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“…The HIA approximation is usually employed for compounds with extreme localization of certain valence electrons. For example, it was applied to a series of rare-earth-based compounds and showed a good agreement with the measured photoemission spectra and ground state properties [25][26][27][28].…”

Section: Theoretical Methodsmentioning

confidence: 81%

Exchange parameters of strongly correlated materials: Extraction from spin-polarized density functional theory plus dynamical mean-field theory

et al. 2015

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In this paper we present an accurate numerical scheme for extracting interatomic exchange parameters (J ij ) of strongly correlated systems, based on first-principles full-potential electronic structure theory. The electronic structure is modeled with the help of a full-potential linear muffin-tin orbital method. The effects of strong electron correlations are considered within the charge self-consistent density functional theory plus dynamical mean-field theory. The exchange parameters are then extracted using the magnetic force theorem; hence all the calculations are performed within a single computational framework. The method allows us to investigate how the J ij parameters are affected by dynamical electron correlations. In addition to describing the formalism and details of the implementation, we also present magnetic properties of a few commonly discussed systems, characterized by different degrees of electron localization. In bcc Fe, treated as a moderately correlated metal, we found a minor renormalization of the J ij interactions once the dynamical correlations are introduced. However, generally, if the magnetic coupling has several competing contributions from different orbitals, the redistribution of the spectral weight and changes in the exchange splitting of these states can lead to a dramatic modification of the total interaction parameter. In NiO we found that both static and dynamical mean-field results provide an adequate description of the exchange interactions, which is somewhat surprising given the fact that these two methods result in quite different electronic structures. By employing the Hubbard-I approximation for the treatment of the 4f states in hcp Gd we reproduce the experimentally observed multiplet structure. The calculated exchange parameters result in being rather close to the ones obtained by treating the 4f electrons as noninteracting core states.

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Section: Theoretical Methodsmentioning

confidence: 81%

Exchange parameters of strongly correlated materials: Extraction from spin-polarized density functional theory plus dynamical mean-field theory

et al. 2015

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“…The f removal energies one observes in photoemission include all the atomic multiplets of the f n−1 ion left behind, which can lead to a spectral function with f-related features over a ϳ10 eV range. 19,55 Even calculating the energy of the most stable state with one f-electron removed is difficult. First of all, this will usually not be the ground state for an N − 1 electron system, so applying a density functional theory based formalism poses a problem.…”

Section: F Removal Energiesmentioning

confidence: 99%

Electronic structure of rare-earth impurities in GaAs and GaN

et al. 2006

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The electronic structures of substitutional rare-earth (RE) impurities in GaAs and cubic GaN are calculated. The total energy is evaluated with the self-interaction corrected local spin density approximation, by which several configurations of the open 4f shell of the rare-earth ion may be investigated. The defects are modelled by supercells of type REGa$_{n-1}$As$_n$, for n=4, 8 and 16. The preferred defect is the rare-earth substituting Ga, for which case the rare-earth valency in intrinsic material is found to be trivalent in all cases except Ce and Pr in GaN. The 3+ --> 2+ f-level is found above the theoretical conduction band edge in all cases and within the experimental gap only for Eu, Tm and Yb in GaAs and for Eu in GaN. The exchange interaction of the rare-earth impurity with the states at both the valence band maximum and the conduction band minimum is weak, one to two orders of magnitude smaller than that of Mn impurities. Hence the coupling strength is insufficient to allow for ferromagnetic ordering of dilute impurities, except at very low temperatures.Comment: 12 pages, 10 figure

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“…In solids the 15 lanthanides (atomic numbers [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71] usually exist in a 3+ state, with three electrons (two of s and one of d character) donated to the valence band. Grouping the lanthanides with Y and Sc, which behave in the same way, forms the group of elements known as the "rare earths" (REs) [1].…”

Section: Introductionmentioning

confidence: 99%

Rare-earth/transition-metal magnets at finite temperature: Self-interaction-corrected relativistic density functional theory in the disordered local moment picture

Patrick

Staunton

2018

Phys. Rev. B

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Atomic-scale computational modeling of technologically relevant permanent magnetic materials faces two key challenges. First, a material's magnetic properties depend sensitively on temperature, so the calculations must account for thermally induced magnetic disorder. Second, the most widelyused permanent magnets are based on rare-earth elements, whose highly localized 4f electrons are poorly described by standard electronic structure methods. Here, we take two established theories, the disordered local moment picture of thermally induced magnetic disorder and selfinteraction-corrected density functional theory, and devise a computational framework to overcome these challenges. Using the new approach, we calculate magnetic moments and Curie temperatures of the rare-earth cobalt (RECo5) family for RE=Y-Lu. The calculations correctly reproduce the experimentally measured trends across the series and confirm that, apart from the hypothetical compound EuCo5, SmCo5 has the strongest magnetic properties at high temperature. An orderparameter analysis demonstrates that varying the RE has a surprisingly strong effect on the Co-Co magnetic interactions determining the Curie temperature, even when the lattice parameters are kept fixed. We propose the origin of this behavior is a small contribution to the density from f -character electrons located close to the Fermi level. arXiv:1806.05646v1 [cond-mat.mtrl-sci]

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Electronic structure and spectroscopic properties of thulium monochalcogenides

Cited by 37 publications

References 43 publications

Exchange parameters of strongly correlated materials: Extraction from spin-polarized density functional theory plus dynamical mean-field theory

Exchange parameters of strongly correlated materials: Extraction from spin-polarized density functional theory plus dynamical mean-field theory

Electronic structure of rare-earth impurities in GaAs and GaN

Rare-earth/transition-metal magnets at finite temperature: Self-interaction-corrected relativistic density functional theory in the disordered local moment picture

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