Unusual magnetic transitions in a new ternary compound: TbCo3Ga2

Abstract Two new ternary compounds of the composition RCo 3 Ga 2 ( R = Tb , Y ) have been prepared and identified by X-ray diffraction. The compounds crystallize in a new hexagonal structure, forming a ‘superlattice’ with lattice vectors, a and b , that are larger by a factor of √3 compared with the unit cell of the related pseudobinary compound RCo 5- x Ga x . Magnetization and Mossbauer measurements reveal two independent magnetic transitions in TbCo 3 Ga 2 occuring around 20 and 200 K. There are strong indications that the lower transition involves the Co sublattice whereas the higher transition is connected with the Tb sublattice.