Magnetic properties of RIrGe (R=Gd-Er) compounds from neutron diffraction and magnetic measurements

Polycrystalline samples of the ternary intermetallics RIrGe (R = Tb,Ho,Er) were investigated by means of magnetization, X-ray and neutron diffraction measurements. For GdIrGe and DyIrGe only magnetic and X-ray diffraction mea surements were performed. They crystallize in the orthorhombic TiNiSi-type structure. Magnetic measurements show antiferromagnetic ordering with Neel temperatures of 24 K for R = Gd and Tb, 15 K for R = Dy and 6.5 K for R = E r. HoIrGe is paramagnetic down to 1.5 K. Neutron diffraction data for TbIrG e indicate sine modulated magnetic ordering with the propagation vector k = (0,0.4093(2),0) and the magnetic moment parallel to the c-axis. In HoIrGe, no magnetic ordering is observed down to 1.5 K, while in ErIrGe a sine mod ulated structure with the moment parallel to the a-axis is observed below T -N. Below T-t = 2.9 K the coexistence two phases collinear and sine modulat ed is observed. (C) 1999 Elsevier Science S.A. All rights reserved.