Magnetic properties and magnetic structures of RPtGe2 and RIrGe2 (R=Gd-Er) compounds

Magnetic properties and magnetic structures of RTGe2 (R=Gd-Er, T=Pt, Ir) series of ternary intermetallic compounds were determined by X-ray and neutron diffraction and by magnetometric methods. All these compounds exhibit the orthorhombic YIrGe2-type crystal structure and except ErIrGe2, are antiferromagnetic at low temperatures. The rare earth atoms occupy the 4(i) and 4(h) sites. In the case of TbPtGe2, TbIrGe2 and HoIrGe2 only the magnetic moments at the 4(i) site order below the Neel temperature (with the simple propagation vector k=0). At low temperatures the Tb and Ho moments at the 4(h) site order with different propagation vectors. In the DyPtGe2 compound, the Dy magnetic moments at both crystallographic sites order in a collinear antiferromagnetic structure below the Neel temperatures. For ErPtGe2 in the temperature range between 1.5 K and T-N=2.8 K, only the Er magnetic moments at the 4(i) site are ordered. (C) 2001 Elsevier Science B.V. All rights reserved.