Magnetic structure of triangular lattice compound Tb2Ni0.90Si2.94

Abstract AlB2-type ternary intermetallic compound Tb2Ni0.90Si2.94 (space group P 6 / mmm , hP 3 , No. 191) was reported to exhibit spin freezing behaviour of the ferromagnetic clusters present in the system below T f = 9.9 K, along with the presence of spatially limited antiferromagnetic phase. In this work, on the basis of variable temperature zero-field neutron diffraction measurements, we have shown that the antiferromagnetic phase transition occurs for the compound below T N ~ 13 K. Neutron diffraction study indicates ab-plane non-collinear sine-modulated antiferromagnetic ordering of the system with wave vectors of k 1 = [ ± 1 / 6 , ± 1 / 6 , 0 ] and k 2 = [ ± 1 / 3 , ± 1 / 3 , 0 ] down to 1.7 K. The weak and diffuse nature of the magnetic Bragg peaks along with limited coherence length further confirm the short-range nature of the antiferromagnetic phase in this compound.