Magnetic ordering of Cu in Gd2CuO4.

Neutron-diffraction investigations have been performed to determine the magnetic ordering of Cu ions in a 158 Gd-enriched Gd 2 CuO 4 single crystal. The Cu magnetic moments in Gd 2 CuO 4 are found to order at about 285 K to an antiferromagnetic structure with the propagation vector k=(1/2,1/2,0). The antiferromagnetic structure is similar to that of La 2 NiO 4 . The magnetic moments of Cu ions are oriented parallel to [110]