Journal Article

PreJuSER-54427

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Non-Fermi-liquid phases in the two-band Hubbard model: Finite-temperature exact diagonalization study of Hund's rule coupling

Liebsch, A.FZJ* ; Costi, T. A.FZJ*

2006
Springer Berlin

This record in other databases:  

Please use a persistent id in citations: doi:10.1140/epjb/e2006-00248-0

Abstract: The two-band Hubbard model involving subbands of different widths is investigated via finite-temperature exact diagonalization (ED) and dynamical mean field theory (DMFT). In contrast to the quantum Monte Carlo (QMC) method which at low temperatures includes only Ising-like exchange interactions to avoid sign problems, ED permits a treatment of Hund's exchange and other onsite Coulomb interactions on the same footing. The role of finite-size effects caused by the limited number of bath levels in this scheme is studied by analyzing the low-frequency behavior of the subband self-energies as a function of temperature, and by comparing with numerical renormalization group (NRG) results for a simplified effective model. For half-filled, non-hybridizing bands, the metallic and insulating phases are separated by an intermediate mixed phase with an insulating narrow and a bad-metallic wide subband. The wide band in this phase exhibits different degrees of non-Fermi-liquid behavior, depending on the treatment of exchange interactions. Whereas for complete Hund's coupling, infinite lifetime is found at the Fermi level, in the absence of spin-flip and pair-exchange, this lifetime becomes finite. Excellent agreement is obtained both with new NRG and previous QMC/DMFT calculations. These results suggest that-finite temperature ED/DMFT might be a useful scheme for realistic multi-band materials.

Keyword(s): J

Note: Record converted from VDB: 12.11.2012

---

Contributing Institute(s):

1. Theorie III (IFF-TH-III)
2. Theorie I (IFF-TH-I)
3. JARA - HPC (JARA-HPC)

Research Program(s):

1. Kondensierte Materie (P54)
2. Non-equilibrium dynamics of fermionic atoms in optical lattices; transport at oxide interfaces (jiff23_20090701)

Appears in the scientific report 2006

---