Magnetic and neutron diffraction studies on double perovskites A2LnRuO6 (A = Sr, Ba; Ln = Tm, Yb)

Abstract

Magnetic properties of double perovskites A₂LnRuO₆ (A = Sr, Ba; Ln = Tm, Yb) have been reported. Powder neutron diffraction measurements have been performed at 10 K and higher temperatures (≥100 K) to determine their crystal and magnetic structures. As a result of the Rietveld analysis of the diffraction profiles, it is found that they are monoclinic with space group P2₁/n (A = Sr) or cubic with space group Fmm (A = Ba). From the magnetic susceptibility and specific heat measurements, a magnetic transition at 36–48 K is observed in each compound. The neutron diffraction data collected at 10 K show that this magnetic transition is due to a long range antiferromagnetic ordering involving both Ru⁵⁺ and Ln³⁺ ions. Each of the magnetic moments of Ru⁵⁺ and Ln³⁺ orders in a type I arrangement.