TY  - JOUR
AU  - Liebsch, A.
AU  - Costi, T. A.
TI  - Non-Fermi-liquid phases in the two-band Hubbard model: Finite-temperature exact diagonalization study of Hund's rule coupling
JO  - The European physical journal / B
VL  - 51
SN  - 1434-6028
CY  - Berlin
PB  - Springer
M1  - PreJuSER-54427
SP  - 523
PY  - 2006
N1  - Record converted from VDB: 12.11.2012
AB  - 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.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000238670700008
DO  - DOI:10.1140/epjb/e2006-00248-0
UR  - https://juser.fz-juelich.de/record/54427
ER  -