2003/04/28 by Y. Ono, K. Sano
Physics and Astronomy · #cond-mat.str-el #cond-mat.supr-con
published as J. Phys. Soc. Jpn. 71 (2002) Supplement 356-358 · 3 pages, 5 figures, proceedings of the International Conference on Strongly Correlated Electrons with Orbital Degrees of Freedom (ORBITAL2001)
arxiv created 2003/04/28 · arxiv updated 2009/11/30
We study a two-band Hubbard model using the dynamical mean-field theory combined with the exact diagonalization method. At the electron density n=2, a transition from a band-insulator to a correlated semimetal occurs when the on-site Coulomb interaction U is varied for a fixed value of the charge-transfer energy Δ. At low temperature, the correlated semimetal shows ferromagnetism or superconductivity. With increasing doping |n-2|, the ferromagnetic transition temperature rapidly decreases and finally becomes zero at a critical value of n. The second-order phase transition occurs at high temperature, while a phase separation of ferromagnetic and paramagnetic states takes place at low temperature. The superconducting transition temperature gradually decreases and finally becomes zero near n=1 (n=3) where the system is Mott insulator which shows antiferromagnetism at low temperature.