Synthesis and characterization of the new two-dimensional Heisenberg antiferromagnet double perovskite BaLaCuSbO6

Abstract

The BaLaCuSbO₆ double perovskite has been successfully synthesized by solid state reaction under an air atmosphere. Its structure was refined using powder neutron diffraction in the monoclinic space group I2/m with a 4% antisite disorder on the B cations. Magnetic measurements give signs of 2D-antiferromagnetic behaviour with T_N around 64 K. The Jahn–Teller distortion produced by Cu²⁺ ions favours a crystallographic tetragonal distortion and consequently the in-plane super–superexchange antiferromagnetic interactions, J^90°, are favoured over the in-plane J^180° antiferromagnetic exchange interactions. Both, J and J′ magnetic interactions have been evaluated according to a Heisenberg antiferromagnetic rectangular model using an approximation to Curie's law in powers of J/T, being |J| around 10 times stronger than |J′|.