Magnetic and transport properties of Na doped SrRuO3 and CaRuO3

The magnetic susceptibility chi(T) (2 less than or equal to T less than or equal to 400 K) and electrical resistivity rho(T) (2 less than or equal to T less than or equal to 300 K) of undoped and Na doped SrRuO3 and CaRuO3 single crystals were measured. These two perovskites are orthorhombic with space group Pbnm. While both of the undoped systems exhibit metallic conductivity, SrRO(3) is ferromagnetic with T-c less than or equal to 160 K, but CaRuO3 is paramagnetic. When a small concentration of Na (less than or equal to 12%) replaces Sr in the structure, SrRuO3 becomes an insulator with a depressed ferromagnetic response. In contrast, Na doped CaRuO3 (less than or equal to 5%) remains metallic with the appearance of antiferromagnetism below 70 K. The dramatic changes in magnetic and transport properties resulting from Na replacement of Sr and Ca reflects the very subtle differences driving the magnetism in SrRuO3 and CaRuO3. (C) 1996 American Institute of Physics.