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 ${\chi }_a{\text{\hspace{0.17em}=\hspace{0.17em}1.09\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−6}}{\mathrm{cm}}^3/\mathrm{g}$ and ${\chi }_a{\mathrm{\hspace{0.17em}/\hspace{0.17em}\chi }}_c\text{\hspace{0.17em}=\hspace{0.17em}0.80}$ , and for IrO₂ at 300°K ${\chi }_a{\text{\hspace{0.17em}=\hspace{0.17em}0.92\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−6}}{\mathrm{cm}}^3/\mathrm{g}$ and ${\chi }_a{\mathrm{\hspace{0.17em}/\hspace{0.17em}\chi }}_c\text{\hspace{0.17em}=\hspace{0.17em}1.19}$ . Our results are discussed and compared with the behavior of the susceptibility of some of the transition metals. The temperature dependence of ${\chi }_m$ in RuO₂ is quite similar to that for some transition metals. The temperature dependence of ${\chi }_m$ in IrO₂ below 30°K is quite different possibly owing to trace impurities.