Magnetic Properties of SrRuO3 and CaRuO3

Magnetization measurements of SrRuO₃ and CaRuO₃ confirm that SrRuO₃ is ferromagnetic with T_C = (160±5) °K and that CaRuO₃ has antiferromagnetic exchange interactions dominant. They further identify in CaRuO₃ a Néel temperature T_N = (110±10) °K and parasitic ferromagnetism below T_N having a σ₀ = (3.2±0.4) × 10^-2 emu/g at 4.2°K. High-field (to 125 kOe) magnetization and neutron-diffraction data for SrRuO₃ are consistent with a reduced spontaneous ferromagnetic moment μ₀ = (1.4±0.4) μ_B and no ordered antiferromagnetic component. Resistivity measurements confirm a low resistivity (ρ<10^-3Ω.cm) at room temperature having a metallic temperature coefficient. It is concluded that both compounds represent spontaneous collective-electron magnetism and that the reduced moment of SrRuO₃ is due to holes in both the up-spin and down-spin bands. Antiferromagnetic CaRuO₃ is predicted to have narrower ``4d'' bands.