Antiferromagnetic order of Cu in Sm2CuO4

Abstract

Neutron diffraction techniques have been used to study the magnetic order of the Cu ions in a single crystal of Sm2CuO4. The measurements revealed the development of long-range magnetic order of the Cu moments at TN = 280 ± 1 K, with a relatively simple antiferromagnetic configuration of spins as found in Nd2CuO4 and Pr2CuO4. However, the spin directions in Sm2CuO4 are rotated by 90° from the spin directions in Nd2CuO4 and Pr2CuO4. The detailed spin structure can be either collinear or noncollinear, and in these tetragonal systems it is not possible to distinguish between them with the present neutron diffraction data on multidomain samples. Our measurements demonstrate that there are no spin reorientations below the Néel temperature, in contrast to the behavior found for Nd2CuO4.