Regensburg 2022 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 6: Kondo Physics, f-Electron Systems and Heavy Fermions

TT 6.11: Vortrag

Montag, 5. September 2022, 17:45–18:00, H22

Theory of valence-band photoemission from Am metal — •Jindrich Kolorenc — Institute of Physics (FZU), Czech Academy of Sciences, Praha, Czech Republic

The 5f states in americium metal are generally agreed to be localized, similar to 4f states in lanthanides, being in a well-defined 5f⁶ configuration (Am³⁺). In the same time, the valence-band photoemission spectrum [1,2] cannot be interpreted as a single set of multiplet transitions (5f⁶→5f⁵) like in lanthanides [3], and a second set of multiplets (5f⁷→5f⁶) has to be introduced [4]. Two mechanisms were suggested as a possible origin of these additional transitions: (i) Am²⁺ layer forming at the surface of the sample or (ii) a second screening channel for the 5f hole created during the photoemission process, with the second mechanism later determined as more likely [2]. Up to now, there does not seem to be a quantitative theory that would substantiate these empirical ideas. The best attempt to date [5] combined the DFT+DMFT method with a generalized Hubbard-I impurity solver, which reproduced the 5f⁷→5f⁶ part of the spectrum well, but it also generated a spurious 5f intensity at the Fermi level. Here I report a DFT+DMFT study employing a more accurate impurity solver (exact diagonalization) and demonstrate the mechanism leading to the 5f⁷→5f⁶ multiplets in the Am PES spectra.

[1] J. R. Naegele et al., Phys. Rev. Lett. 52, 1834 (1984)

[2] T. Gouder et al., Phys. Rev. B 72, 115122 (2005)

[3] J. K. Lang et al., J. Phys. F: Met. Phys. 11, 121 (1981)

[4] N. Mårtensson et al., Phys. Rev. B 35, 1437 (1987)

[5] A. Svane, Solid State Commun. 140, 364 (2006)