MAGNETIC-PROPERTIES OF TBMNSI, DETERMINED BY SUSCEPTIBILITY MEASUREMENTS AND NEUTRON-DIFFRACTION STUDY

Investigations made by powder X-ray diffraction, susceptibility measur ements and neutron diffraction experiments on the ternary silicide TbM nSi are reported. This compound crystallizes in the tetragonal structu re of the CeFeSi-type (space group, P4/nmm). It exhibits a ferrimagnet ic behaviour below T(C)=260 K. The magnetization value and the coerciv e field are 2.7 mu(B) and 6 kOe, respectively, at 4.2 K. Neutron diffr action study confirms that both Mn and Th sublattices order simultaneo usly at 260 K. The magnetic structure consists of Mn and Tb ferromagne tic (001) layers coupled antiferromagnetically (mu(Mn) = 2.2 mu(B) and mu(Tb) = 8.45 mu(B) at 2 K). The occurrence of a ferromagnetic Mn(001 ) layer in this CeFeSi-type structure compound is discussed.