Magnetic ordering in the Nd2CoMnO6+delta perovskite system

The properties of the Nd2CoMn06+b (S = 0, 0.12) system were investigated by the neutron powder diffraction method. An as-prepared non-stoichiometric sample (S = 0.12) has an orthorhombically distorted perovskite structure with a random distribution of the Co 2+ and Mn 41 ions. On the other hand, the reduction to a stoichiometric compound (6 = 0) leads to ionic ordering and therefore to lowering the crystal structure symmetry to a monoclinic one. According to neutron diffraction data both samples exhibit ferromagnetic component. It was also found that ionic disordering leads to a decrease in the total magnetic moment and the appearance of a spin-glass-like component. This component transforms into the ferromagnetic one as first-order phase transition in an applied external magnetic field.