We have studied transport and magnetic properties of ruthenium pyrochlore oxides R2−xBixRu2O7 (R = rare earth, Y), which exhibit the Mott insulator to metal transition with increasing x. The spin-glass transition can be observed basically in the insulating x-region, which may be due to the freezing of Ru spins. Transport quantities, the electrical resistivity ρ, the Hall coefficient RH and the thermoelectric power S are found to be strongly affected by the spin-glass transition. Furthermore, near the metal-insulator phase boundary, RH increases rather rapidly with decreasing temperature and the Hall angle θH obeys the relation cot θH = a+bT2 in the paramagnetic state. These results suggest that there exist strong spin fluctuations in the metallic state of R2-xBixRu2O7, which is suppressed as the spin freezing proceeds.
ASJC Scopus subject areas
- 化学 (全般)