Crystal and magnetic structures of the double perovskite La2CoRuO6

Abstract

The crystal and magnetic structures of the double perovskite La₂CoRuO₆ have been investigated using neutron powder diffraction. La₂CoRuO₆ has a monoclinic P2₁/n superstructure (a = 5.5724(3) Å, b = 5.6288(3) Å, c = 7.8843(4) Å and β = 89.99(2)°) with a rocksalt ordered arrangement of Co and Ru over the perovskite B sites (showing 10% Co/Ru inversion). Bond valence sums indicate the presence of Co²⁺ and Ru⁴⁺. Magnetization and transport measurements confirm La₂CoRuO₆ is an antiferromagnetic variable range hopping semiconductor with a Neel temperature of 25 K. The antiferromagnetic ordering is described by a (½ 0 ½) magnetic propagation vector but the spin directions cannot be determined unambiguously from neutron powder diffraction data because of the high pseudosymmetry.