Magnetic properties of La2CuTi1–xRuxO6 and La2ZnRuO6

Abstract

The compound La₂CuRuO₆ has been prepared by standard ceramic techniques and characterized by X-ray powder diffraction and magnetometry. The Cu²⁺ and Ru⁴⁺ cations are partially (≈80%) ordered over the six-coordinate (B) sites of a monoclinic perovskite structure [a= 5.5897(2)Å, b= 5.7550(2)Å, c= 7.7584(2)Å, β= 90.15°]. The material shows a transition to a weakly ferromagnetic phase at 12 K. Substitution of Ti⁴⁺ for 20% of the Ru cations leads to the loss of both the cation ordering and the spontaneous magnetization, although there is some evidence for the formation of superparamagnetic spin clusters and, below 10 K, a freezing of frustrated spins. The magnetically dilute but structurally ordered compound La₂ZnRuO₆ is paramagnetic down to a temperature of 6 K.