Speaker: Dr. Seung-Seop B. Lee (LMU of Munich)
Date & Time: Apr. 5 (Mo) 4:00 PM.
제목 : Hund metals: spin-orbital separation and orbital differentiation
Webex Meeting link: https://knu.webex.com/knu/j.php?MTID=m6222ded398db956d821c4d1dd346af31
Hund metals are a broad class of multiorbital systems in which strong correlations are driven not only by Hubbard repulsion but also by Hund’s rules. The Hund coupling leads to two hallmarks of Hund metals: The energy scale of screening local spin fluctuations is much smaller than that for orbital fluctuations ("spin-orbital separation"). Also, almost degenerate orbitals can have largely different behaviors ("orbital differentiation"); the orbital-selective Mott phase is one of its extrema. In this talk, I will present our dynamical mean-field theory (DMFT) studies of these hallmarks in a three-band model  and a first-principles description of Sr2RuO4 , where the numerical renormalization group (NRG) is used as a powerful real-frequency impurity solver. I will also show that exotic metallic phases, such as non-Fermi liquid and singular Fermi liquid, can appear in the spin-orbital separation energy window [3, 4].
 F. B. Kugler, S.-S. B. Lee, A. Weichselbaum, G. Kotliar, and J. von Delft, Phys. Rev. B 100, 115159 (2019).
 F. B. Kugler, M. Zingl, H. U. R. Strand, S.-S. B. Lee, J. von Delft, A. Georges, Phys. Rev. Lett. 124, 016401 (2020).
 E. Walter, K. M. Stadler, S.-S. B. Lee*, Y. Wang, G. Kotliar, A. Weichselbaum, and J. von Delft, Phys. Rev. X 10, 031052 (2020).
 Y. Wang, E. Walter, S.-S. B. Lee, K. M. Stadler, J. von Delft, A. Weichselbaum, and G. Kotliar, Phys. Rev. Lett. 124, 136406 (2020).