Magnetic and Mossbauer studies of CaRu(1-)xM(x)O(3) (M = Ti and Fe)

Abstract

CaRuO3 is a perovskite with an orthorhombic distortion and shows the characteristics of spin-glass behavior below T-C=87 K. Magnetic studies of polycrystalline CaRu1-xTixO3 (0 LT x LT 0.1) reveal that a ferromagnetic transition at T-C=34 K appears regardless of the nonmagnetic Ti concentration. On the other hand, magnetic and Mossbauer effect studies show that T-C of CaRu1-xFexO3 (up to x=0.15) is similar to that of pure CaRuO3: however, the Fe induces a ferromagnetic structure. Charge compensation, which is assumed to be present upon Fe3+ substitution, induces the appearance of low-spin Ru5+ ions, which reduce the paramagnetic moment. Huge magnetic hysteresis loops are observed at 5 K, with coercive fields up to 30 kOe. A second magnetic transition around 250 K is observed for Fe concentrations of x=0.25 and 0.35, which is probably caused by Fe-rich clusters. This behavior is consistent with inhomogeneous ferromagnetism found in other perovskite systems.