Effects of spin-dependent quasiparticle renormalization in Fe, Co, and Ni photoemission spectra:An experimental and theoretical study

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.

Momentum space anisotropy of electronic correlations in Fe and Ni: An analysis of magnetic Compton profiles

“…In addition the magnetic exchange-splitting is overestimated by LSDA calculations when compared with the experimental data. An improved description of correlation effects for the 3d electrons via LSDA+DMFT gives a more correct width of the occupied 3d bands, a better exchange splitting, and also the 6 eV satellite structure in the valence band [17,39,[49][50][51][52][53][54].…”

Ultrafast magnetization dynamics: Microscopic electronic configurations and ultrafast spectroscopy

“…Correlation effects in Fe are indeed moderate 42 , even when compared to other 3d transition metals 43 . Excitation energies in the typical experimental setups we want to address are below a few hundreds of meV per atom.…”

Spin-Resolved Valence Photoemission

“…The comparison also highlighted that with increasing Z, nonlocal correlation effects get weaker while local effects get stronger [162][163][164].…”