3-DIMENSIONAL MAGNETIC-STRUCTURES AND RARE-EARTH MAGNETIC-ORDERING IN ND2CUO4 AND PR2CUO4

The three-dimensional (3D) magnetism present in Nd2CuO4 and Pr2CuO4 has been examined in neutron-scattering experiments. Antiferromagnetic long-range order of the Cu2+ moments develops below TN=255 K in both compounds. In Nd2CuO4 a series of magnetic phase transitions in which the Cu2+ spins reorient has also been observed below TN, while in Pr2CuO4 the 3D Cu2+ spin structure is stable. No changes in the crystalline structure of Nd2CuO4 associated with the spin-reorientation transitions were found. Induced ordering of the rare-earth magnetic moments has been observed in both compounds. The Nd3+ (Pr3+) magnetic moments align parallel (antiparallel) to Cu2+ moments which are nearest neighbors along the c axis, and the ordered moments of the rare-earth ions were determined to be 1.3B for Nd3+ at 0.4 K and 0.08B for Pr3+ at 8 K. The temperature-dependent Pr3+ moment is shown to be proportional to the Cu2+ moment times the bulk susceptibility. In this paper we also discuss the role of the XY anisotropy in the 3D ordering. © 1990 The American Physical Society.