Crystal and magnetic structures of the R(=Y, Dy–Tm)MnGe compounds

• Published in: Journal of magnetism and magnetic materials 2003, Vol.256 (1), p.69-92
• Main Authors: Klosek, V., Vernière, A., Ouladdiaf, B., Malaman, B.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Germanides; Inorganic compounds; Magnetic properties and materials; Magnetic structures; Magnetically ordered materials: other intrinsic properties; Manganese compounds; Neutron diffraction; Physics; Rare-earth ternary compounds; Saturation moments and magnetic susceptibilities; Single-crystal and powder diffraction; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; X-ray diffraction and scattering
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(02)00383-9

Powder and single-crystal X-ray diffraction, susceptibility measurements and powder neutron diffraction studies on RMnGe compounds (R=Dy–Tm, Y) are reported. The R(=Dy–Er, Y)MnGe compounds crystallize in the TiNiSi-type (S.G. Pnma) while two polytypic forms (H.T.-ZrNiAl and L.T.-TiNiSi) characterize the TmMnGe compound. All compounds exhibit antiferromagnetic ordering of the Mn sublattice above room temperature, while the R sublattice orders antiferromagnetically at 85 (5), 70 (5), 60 (5) and 30 (5) K for R=Dy, Ho, Er and Tm, respectively. At 2 K, DyMnGe is characterized by a cycloid structure ( q x ∼0.227) whereas HoMnGe exhibits a conical structure ( q x ∼0.259). YMnGe, ErMnGe and TmMnGe are simple collinear antiferromagnets, and a spin-reorientation process occurs in TmMnGe below 25 (2) K. At 2 K, the values of the magnetic moments are: μ Mn=3.37(14) μ B, μ Dy=8.87(13) μ B; μ Mn=3.35(9) μ B, μ Ho=8.03(12) μ B; μ Mn=3.25(18) μ B, μ Er=7.51(39) μ B; μ Mn=3.19(12) μ B, μ Tm=6.40(11) μ B; μ Mn=3.51(15) μ B for DyMnGe, HoMnGe, ErMnGe, TmMnGe and YMnGe, respectively. In all cases, the magnetic structures are characterized by antiferromagnetic [0 1 0] Mn chains. The results are discussed in terms of R–R, R–Mn, Mn–Mn interactions and anisotropy effects.