STUDY ON MAGNETIC-ORDERING IN (LA, ND, SR)2CUO4

Spin structures of La1.65Nd0.35CuO4, which undergoes a structural transition at T = T'1 is similar to 80 K from the orthorhombic (Bmab) to another orthorhombic (Pccn) phase, have been studied by single crystal neutron diffraction and magnetization measurements. The Neel temperature T(N) was found to be about 303 K. Above T'1, the La2CuO4-type spin structure is observed. Below T'1, the observed intensities can be explained by the mixtures of the La2CuO4-type and La2NiO4-type spin structures with spin cantings. Search for the spin ordering in La1.49Nd0.39Sr0.12CuO4 has also been carried out in the low-temperature tetragonal (P4(2)/ncm) phase, where the superconductivity is suppressed, but no evidence for the ordering has been observed.