MAGNETIC-STRUCTURE OF TBIRSI3 COMPOUND

The paper reports on neutron diffraction and magnetic measurements of TbIrSi3. The compound crystallizes in the tetragonal BaNiSn3-type of s tructure. Below 16 K, the Tb-magnetic moments order antiferromagnetica lly. In the temperature region 1.6-7.4 K, a collinear antiferromagneti c structure of AFI-type with the moment in the basal plane is observed . With increasing temperature, the magnetic structure changes into a t ransversal sine-wave modulated structure. In the temperature region 7. 8-11 K, a collinear and a sine-modulated structure coexist whereas in the region 11-16 K, a sine-modulated one is detected. The data are bri efly discussed in terms of the RKKY theory and electric-field model. ( C) 1998 Elsevier Science S.A.