Magnetic ordering in ErFe6Sn6

We have determined the magnetic structures of the Er and Fe sublattices in ErFe6Sn6 by high-resolution neutron powder diffraction and Mossbauer spectroscopy on the Er-166, Fe-57 and Sn-119 isotopes. The crystal space group is orthorhombic Cmcm. The Fe sublattice is antiferromagnetic with a Neel temperature of 560(5) K and it orders along the [100] direction with a magnetic space group C(p)m'c'm' and a propagation vector [010]. The Fe magnetic moment at 1.5 K is 2.4 +/- 0.6 mu(B). The Er sublattice orders independently of the Fe sublattice at 4.8 +/- 0.4 K and comprises a ferromagnetic mode along [100] and an antiferromagnetic mode along [010], with a propagation vector [0 1/2 0] i.e. cell-doubling along [010]. The magnetic space group of the Er sublattice within the magnetic unit cell is Pbc'm', a subgroup of Cmcm. At 1.5 K the ferromagnetic and antiferromagnetic components of the Er3+ magnetic moment (determined by a combination of neutron diffraction and magnetization measurements) are 5.9 +/- 0.1 and 4.9 +/- 1.5 mu(B), respectively, yielding a net Er moment of 7.7 1.5 AB. The Er3+ magnetic moment derived from Er-166 Mossbauer spectroscopy is 8.5 (1) mu(B).