Static and dynamic conductivity for a model of Tl2Mn2O7

Abstract The compound Tl 2 Mn 2 O 7 exhibits colossal magneto resistance, which is not adequately explained by the double exchange mechanism. We use Hubbard operators to reformulate a previous model of Ventura and Alascio (Phys. Rev. B 56 (1997) 14533), and we obtain approximate one-electron Green's functions (GF) for this model, using a method introduced by Foglio and Figueira (Phys. Rev. B 60 (1999) 11361). With these GF we calculate the static and dynamic conductivity, both with and without applied magnetic fields.