Magnetic phase diagram of metallic pyrochlore lattice in the double-exchange model

The magnetic phase diagram of metallic kagomé and pyrochlore lattices at the ground state have been studied theoretically in the double-exchange model using a mean-field approximation. The model includes the hopping of itinerant electrons, which is expressed by a single tight-binding band, antiferromagnetic coupling between localized spins, and ferromagnetic exchange interaction between the localized and itinerant electron spins. The phase diagram was found to be rather insensitive to the ferromagnetic exchange interaction but to show a rich variety in magnetic structure with doping. A crossover between ferromagnetic and spin glass phases observed in RE₂Mo₂O₇ pyrochlore lattices, where RE denotes rare-earth ions, is discussed in view of the calculated results.