THE ELECTRONIC-PROPERTIES OF NONSTOICHIOMETRIC BARIUM IRIDATE, BAIRO3-DELTA

Polycrystalline single-phase samples of BaIrO2.73 and BaIrO2.96 were successfully prepared. Superconducting quantum interference device data indicate the the magnetic susceptibility of both samples is low and only weakly temperature dependent in the range 180 K < T < 296 K, demonstrating the presence of delocalized electrons. The materials exhibit high electrical conductivity which is dependent on the oxygen stoichiometry. In addition, magnetic susceptibility data for both compositions show that a transition to a ferromagnetically ordered state occurs at 180 K. It is proposed that this ferromagnetism arises from a difference in the relative populations of the alpha and beta spin bands and not from localized electrons.