Canted antiferromagnetic structure of the novel compound Er3Ge4 by neutron diffraction and magnetic measurements

The magnetic ordering of the novel orthorhombic compound Er3Ge4 (Cmcm) with two Er sites has been studied by neutron diffraction and magnetic measurements. Er3Ge4 orders antiferromagnetically below T-N = 7.3 K. The magnetic moments of the Er-1 atoms (at 8(f)) make an angle of 35.5(3)degrees with the y-axis while the moments of the Er-2 atoms (at 4(a)) are perpendicular to it within the (0, y, z) plane. This triangular antiferromagnetic moment arrangement of the two sublattices in the plane (0, y, z) relates to the stacking of the rare earth triangular prism slabs along the a axis. Adjacent prisms along b or c are shifted by x = 1/2 and display different chiralities. The 1.5 K ordered magnetic moment values of Er-1 and Er-2 are 7.32(5)mu(B)/Er and 6.37(6)mu(B)/Er, respectively. The two Er sublattices order simultaneously but display a completely different thermal behaviour indicating the existence of competing interactions. The magnetic space group C-p(22'2(1)'/m'cm)) (Sh(57)(391)) has a primitive lattice associated with the wave vector q = (010).