Effect of heterovalent ion substitution on the crystalline structure and magnetic ordering of SrRuO3

Structural and magnetic studies have been carried out on SrRu1-xMxO3 (M=Ga:x=0.1; Cu and Zn: x=0.1 and 0.2) in order to understand the dependence of the ferromagnetic transition temperature of SrRuO3 on heterovalent magnetic and nonmagnetic cation substitution at the Ru site. Powder x-ray diffraction has been carried out to analyze the crystal structure using the Rietveld refinement procedure. T-c decreases more rapidly for divalent cation dopants as compared to the trivalent cations. The refinement results show that there are distortions of the RuO6 octahedra in the doped compounds, with little change in the lattice parameters. However, the direction and magnitudes of the tilt of the octahedra for all the compounds do not show correlation with the T-c. Therefore, the change of T-c is attributed to the charge and spin disorders introduced by the heterovalent dopant cations. The filled e(g) orbitals in Ga, Cu, and Zn ions are expected to have weak hybridization with the oxygen p orbitals as compared to the pristine compound, leading to a weakening of the overall ferromagnetic interactions between the Ru ions. (c) 2007 American Institute of Physics.