Magnetic properties of RPdGe2 (R=Y, Gd, Tb, Dy) compounds

Magnetic measurements have been performed on some orthorhombic RPdGe2 compo unds (R = Y, Gd, Tb, Dy), as well as some non-stoichiometric RPdxGe2 compou nds (R = Nd, Gd, Ho, x < 1). The compounds with x = 1 and R = Gd and Tb ord er antiferromagnetically with Neel temperatures of 5.5 K and 28 K, respecti vely. DyPdGe2 seems to remain paramagnetic down to 2 K while YPdGe2 does no t present any magnetic ordering. Neutron diffraction performed on TbPdGe2 r eveals a second transition at 6.5 K. Above this temperature, only one of th e two Tb sites is ordered with a simple ((q) over right arrow = 0) propagat ion vector. Below 6.5 K the moments of the second Tb site become ordered wi th a different propagation vector (q) over right arrow = (0, 1/2, 1/2). Suc h a behaviour reveals a decoupling of both Tb crystallographic sites. (C) 1 999 Published by Elsevier Science S.A. All rights reserved.