Magnetic Susceptibility of IrO2 and RuO2

We have measured the magnetic susceptibility of IrO2 and RuO2 in the temperature range 4.2–300°K using the Faraday technique. We find for RuO2 at 300°K χa = 1.09 × 10−6cm3/g and χa / χc = 0.80, and for IrO2 at 300°K χa = 0.92 × 10−6cm3/g and χa / χc = 1.19. Our results are discussed and compared with the behavior of the susceptibility of some of the transition metals. The temperature dependence of χm in RuO2 is quite similar to that for some transition metals. The temperature dependence of χm in IrO2 below 30°K is quite different possibly owing to trace impurities.