Magnetic ordering in RPtX (R=Gd,Tb,Dy; X=Si,Ge) compounds

GdPtX, TbPtX and DyPtX (X=Si, Ge) crystallize in the orthorhombic TiNiSi-ty pe crystal structure. Magnetometric measurements show that all compounds (e xcept GdPtSi) are antiferromagnetic at low temperatures. GdPtSi is probably ferromagnet below 16 K. The Neel temperature of GdPtGe is at 12.5 K. Neutr on diffraction data indicate the presence of a complicated magnetic order i n TbPtSi below the Neel point at 12.5 K, The magnetic structure of TbPtGe i s of amplitude-modulated type along the b-axis with the wave vector k = [0, 0.2840(3), 0]. The Neel point of TbPtGe is at 15 K. A collinear antiferrom agnetic ordering with the wave vector k = [1/2, 0, 1/2] is operating in DyP tSi and DyPtGe below the Neel points of 8.2 and 8 K, respectively. (C) 2000 Elsevier Science S.A. All rights reserved.