STRUCTURAL AND MAGNETIC-PROPERTIES OF SR2RUO4-TYPE OXIDES

We have studied the structure and magnetic properties of the Sr2-xCaxR uO4 oxides, as well as those of the main perovskite precursors, i.e. S r2RuO3 and CaRuO3. The Sr2RuO4 compound presents a tetragonal structur e (a approximate to 3.9 Angstrom, c approximate to 12.7 Angstrom, spac e group 14/mmm) isomorphous to the prototype K2NiF4. SrRuO3 shows a fe rromagnetic transition at T-C approximate to 170 K. The magnetic susce ptibility of CaRuO3 seems to indicate an antiferromagnetic behavior, w ith a clear deviation from the Curie-Weiss law below similar to 70 K. However, neutron diffraction data at 1.5 K preclude the existence of l ong range antiferromagnetic ordering in CaRuO3. The magnetic behaviour of Sr2RuO4 indicates a very weak dependence on temperature of the mag netic susceptibility, close to a Pauli paramagnet.