Resumen:
aLaCuSbO6 double perovskite has been successfully synthesized by solid state reaction in air atmosphere. Its structure was refined using powder neutron diffraction in the monoclinic space group I 2/m with a 4% antisite disorder on the B cations. Magnetic measurements give signs of 2D-antiferromagnetic behaviour with TN 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 J180° antiferromagnetic exchange interaction. 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?|.