Frustration and two-dimensional spin ordering in TbRu2Si2, TbRu2Ge2 and DyRu2Si2

Abstract By neutron diffraction investigations on TbRu 2 Si 2 , TbRu 2 Ge 2 and DyRu 2 Si 2 single crystals, we have revealed the existence of two-dimensional spin configurations whose magnetic unit cells are 13 a ×13 a × c , 17 a ×17 a × a , and 9 a ×9 a × c , respectively, where a and c are the lattice constants of the original chemical cell. These magnetic cells contain two paramagnetic rare-earth ion sites at the corner and body-centered positions, due to frustration.