Magnetic ordering of Sm in Sm2CuO4

Long-range antiferromagnetic order of the Sm ions in Sm 2 CuO 4 is observed via neutron diffraction at T N =5.95 K. The magnetic structure consists of ferromagnetic sheets within the a-b planes, with the spins in alternate sheets aligned antiparallel. This spin structure and spin direction are completely different from those observed in any other copper-oxide superconductor system