Comparison of the magnetic properties of isoelectronic Sr_x(Na_0.5La_0.5)_1−xRuO₃ and Sr_xCa_1−xRuO₃ perovskites

The solid solution Sr_x(Na_0.5La_0.5)_1−xRuO₃ (0 < ∼ x < ∼ 1) is reported, and its structural, electronic, and magnetic properties are compared to isoelectronic Sr_xCa_1−xRuO₃. The suppression of ferromagnetic interactions in Sr_xCa_1−xRuO₃ has frequently been attributed to the orthorhombic structural distortion, either through the crossover to classical antiferromagnetic interactions, or to a nearly ferromagnetic metal. Comparison of the magnetic properties of Sr_x(Na_0.5La_0.5)_1−xRuO₃ to Sr_xCa_1−xRuO₃, however, shows that there is a much faster suppression of ferromagnetic interactions in the former case. Neither orthorhombic distortion nor cation size disorder can explain the observed difference. Instead, the difference may be attributed to charge disorder on the A site, which affects the local environment of Ru atoms greatly and leads to the faster suppression of the long-range ferromagnetic state.