Dynamical mean-field study of the ferromagnetic transition temperature of a two-band model for colossal magnetoresistance materials

摘要

The ferromagnetic transition temperature (T_C) of a two-band double-exchange (DE) model for colossal magnetoresistance materials is studied using dynamical mean-field theory in wide ranges of coupling constants, hopping parameters, and carrier densities. The results are shown to be in good agreement with Monte Carlo simulations. When the bands overlap, the value of T_C is found to be much larger than in the one-band case, for all values of the chemical potential within the energy overlap interval. A nonzero off-diagonal hopping produces an additional boost of T_C, showing the importance of these terms, as well as the concomitant use of multiband models, to increase the critical temperatures in DE-based theories.