Magnetic studies of Ca_1-xM_xRuO₃ (M=La and Sr)

CaRuO₃ is a perovskite with an orthorhombic distortion and shows the characteristics of spin-glass behavior below T_C=87K. La³⁺ substitution for Ca²⁺ in Ca_1-xLa _xRuO₃ samples, induces disorder at the Ca site (the A site) and the system becomes antiferromagnetically (AFM) ordered at T _N=58 and 19K for x=0.1 and 0.5, respectively. In the Ca _1-xSr_xRuO₃ system, the Ca_0.8Sr _0.2RuO₃ sample is canted-AFM ordered at 107K. The compounds with higher Sr concentration display ferromagnetic behavior and the saturation moment increases with increasing Sr content. Huge magnetic hysteresis loops are obtained at low temperatures. The coercive field (H _C) decreases with increasing Sr content. For pure SrRuO₃ H_C=2.4kOe (at 5K) remains practically unchanged up to 50K, shows a peak at 90K and then decreases sharply up to T_C=165K. On the other hand, H_C for x=0.4 and 0.6 (9.5 and 9kOe at 5K) decreases sharply with increasing temperature and than increases again with a peak at 95 and 115K, respectively.