| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Carbone, C., et al.
(författare)
-
Correlated Electrons Step by Step : Itinerant-to-Localized Transition of Fe Impurities in Free-Electron Metal Hosts
- 2010
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:11, s. 117601-
-
Tidskriftsartikel (refereegranskat)abstract
- High-resolution photoemission spectroscopy and ab initio calculations have been employed to analyze the onset and progression of d-sp hybridization in Fe impurities deposited on alkali metal films. The interplay between delocalization, mediated by the free-electron environment, and Coulomb interaction among d electrons gives rise to complex electronic configurations. The multiplet structure of a single Fe atom evolves and gradually dissolves into a quasiparticle peak near the Fermi level with increasing host electron density. The effective multiorbital impurity problem within the exact diagonalization scheme describes the whole range of hybridizations.
|
|
| 7. |
- Sanchez-Barriga, J., et al.
(författare)
-
Effects of spin-dependent quasiparticle renormalization in Fe, Co, and Ni photoemission spectra : An experimental and theoretical study
- 2012
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 85:20, s. 205109-
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the spin-dependent quasiparticle lifetimes and the strength of electron correlation effects in the ferromagnetic 3d transition metals Fe, Co, and Ni by means of spin- and angle-resolved photoemission spectroscopy. The experimental data are accompanied by state-of-the-art many-body calculations within the dynamical mean-field theory and the three-body scattering approximation, including fully relativistic calculations of the photoemission process within the one-step model. Our quantitative analysis reveals that inclusion of local many-body Coulomb interactions are of ultimate importance for a realistic description of correlation effects in ferromagnetic 3d transition metals. However, we found that more sophisticated many-body calculations with larger modifications in the case of Fe and Co are still needed to improve the quantitative agreement between experiment and theory. In general, it turned out that not only the dispersion behavior of energetic structures should be affected by nonlocal correlations but also the line widths of most of the photoemission peaks are underestimated by the current theoretical approaches. The increasing values of the on-site Coulomb interaction parameter U and the band narrowing of majority spin states obtained when moving from Fe to Ni indicate that the effect of nonlocal correlations becomes weaker with increasing atomic number, whereas correlation effects tend to be stronger.
|
|
| 8. |
- Sanchez-Barriga, J., et al.
(författare)
-
Quantitative determination of spin-dependent quasiparticle lifetimes and electronic correlations in hcp cobalt
- 2010
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 82:10, s. 104414-
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a quantitative investigation of the spin-dependent quasiparticle lifetimes and electron correlation effects in ferromagnetic hcp Co (0001) by means of spin-and angle-resolved photoemission spectroscopies. The experimental spectra are compared in detail to state-of-the-art many-body calculations within the dynamical mean-field theory and the three-body scattering approximation, including a full calculation of the one-step photoemission process. From this comparison we conclude that although strong local many-body Coulomb interactions are of major importance for the qualitative description of correlation effects in Co, more sophisticated many-body calculations are needed in order to improve the quantitative agreement between theory and experiment, in particular, concerning the linewidths. The quality of the overall agreement obtained for Co indicates that the effect of nonlocal correlations becomes weaker with increasing atomic number.
|
|
| 9. |
- Costa, Marcio, et al.
(författare)
-
Correlated electronic structure of Fe in bulk Cs and on a Cs surface
- 2013
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 87:11, s. 115142-
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the spectral properties of Fe impurities in a Cs host, for both surface and bulk systems, by means of a combination of density functional theory in the local density approximation and dynamical mean-field theory (LDA + DMFT). The effective impurity model arising in LDA + DMFT was solved via two different techniques, i.e., the Hubbard I approximation and the exact diagonalization. It is shown that noticeable differences can be seen in the unoccupied part of the spectrum for different positions of Fe atoms in the host, despite the fact that hybridization between Fe d-states and Cs is low. Our calculations show good agreement with the experimental photoemission spectra reported by Carbone et al. [Carbone, Veronese, Moras, Gardonio, Grazioli, Zhou, Rader, Varykhalov, Krull, Balashov, Mugarza, Gambardella, Lebegue, Eriksson, Katsnelson, and Lichtenstein, Phys. Rev. Lett. 104, 117601 (2010)].
|
|
| 10. |
- Mazurenko, V. V., et al.
(författare)
-
First-principles modeling of magnetic excitations in Mn-12
- 2014
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:21, s. 214422-
-
Tidskriftsartikel (refereegranskat)abstract
- We have developed a fully microscopic theory of magnetic properties of the prototype molecular magnet Mn-12. First, the intramolecular magnetic properties have been studied by means of first-principles density functional based methods, with local correlation effects being taken into account within the local density approximation plus U (LDA + U) approach. Using the magnetic force theorem, we have calculated the interatomic isotropic and anisotropic exchange interactions and full tensors of single-ion anisotropy for each Mn ion. Dzyaloshinskii-Moriya (DM) interaction parameters turned out to be unusually large, reflecting a low symmetry of magnetic pairs in molecules, in comparison with bulk crystals. Based on these results we predict a distortion of ferrimagnetic ordering due to DM interactions. Further, we use an exact diagonalization approach allowing one to work with as large a Hilbert space dimension as 108 without any particular symmetry (the case of the constructed magnetic model). Based on the computational results for the excitation spectrum, we propose a distinct interpretation of the experimental inelastic neutron scattering spectra.
|
|
