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TT: Fachverband Tiefe Temperaturen

TT 59: Correlated Electrons: Quantum Impurities and Kondo Physics; Other Materials

TT 59.12: Vortrag

Donnerstag, 19. März 2020, 18:00–18:15, HSZ 03

LDA+DMFT view on electronic structure and magnetism of UGa₂ — •Banhi Chatterjee and Jindrich Kolorenc — Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic

Whether the uranium 5f electrons are closer to being localized or itinerant in the intermetallic compound UGa₂ is still debated. The experimental magnetic moments are large, approximately 3 µ_B, favoring the localized picture. LDA severely underestimates the moments. Although the moments are enhanced within LDA+U, they do not reach the experimental value for a reasonably large U [1]. We investigate if the picture can be improved within LDA+DMFT using exact diagonalization as the impurity solver. We can reproduce the recently measured x-ray absorption spectra at the uranium M edge better than LDA+U [1]. Distinctive spectral features are identified as fingerprints of the localized 5f electrons. We can further recover the experimental valence band photoemission spectra. We present two different formulations of the theory: In LDA+DMFT the polarization is induced only to the 5f states by means of a polarized self-energy, in LSDA+DMFT all states are allowed to polarize. It turns out that neither of the methods gives satisfactory magnetic moments without ad hoc manual intervention in tuning the spin polarized double counting.

[1] A. V. Kolomiets, M. Paukov, J. Valenta, A. V. Andreev, K. Kvashnina, F. Wilhelm, A. Rogalev, D. Drozdenko, P. Minarik, J. Kolorenc, B. Chatterjee, M. Richter, L. Havela (in preparation).