Transport and magnetic properties of pyrochlore ruthenates R2-xBixRu2O7 (R=Sm and Eu), which exhibit the Mott insulator to metal transition with increasing x, have been studied. The electrical resistivity p and the Hall coefficient RH are found to strongly couple to the change of the magnetic state, or the transition to the spin-glass state which takes place at temperature T = TG. Near the metal-insulator phase boundary, RH above TG increases rather rapidly with decreasing T even in the metallic phase, and the Hall angle θH follows a simple relation, cot θH ∝ a + bT2, over the wide T-range. At T = TG, RH has a peak and it decreases with decreasing T. These results indicate that strong spin fluctuations above TG induce the anomalous T-dependence of RH in the present magnetically frustrated three-dimensional system and RH decreases as the spin freezing proceeds.
ASJC Scopus subject areas
- Physics and Astronomy(all)