Neutron powder diffraction study of the ternary RMgSn (R=Ce-Nd, Tb-Tm, Yb) compounds

► Magnetic structure of the whole RMgSn series determined by neutron powder diffraction. ► Sine-wave modulated magnetic structure down to the lowest temperature for TbMgSn. ► Square-wave modulated magnetic structure for RMgSn (R=Dy-Tm) by occurrence of higher odd integer harmonics. ► Magnetic moment orientation of the R atoms in CeScSi-type structure compounds inverse compared to those of isotypic compounds.