Structures and magnetic properties of RM_x compounds (R = rare earth, M = Ge or Si, 1.5 ≤ x ≤ 2) as observed by neutron diffraction

Abstract

Rare earth germanides and silicides of the type RM_x (M = Ge or Si) with x values close to 2 occur in four different structure types: the hexagonal AlB₂ type, the tetragonal α-ThSi₂ type, the orthorhombic α-GdSi₂ type and the orthorhombic TbGe₂ type. A review is given of the occurrence of these structure types in the various R–M systems as observed by neutron diffraction. The occurrence of Si or Ge vacancies in these structures is emphasized and discussed in relation to the magnetic structures observed for these materials.