Crystal structure and magnetic properties of RE(Mn,In)2 (RE = Ho, Er, Tm)

Crystal structure and basic magnetic properties of the compounds RE(Mn,In)2 (RE = Ho, Tm, Er) were investigated. X-ray powder diffraction revealed the MgZn2-type of structure, space group P63/mmc, a = 5.691(1), c = 9.265(2) Å for HoMn1.25In0.75, and a = 5.607(1), c = 9.176(2) Å, for TmMn1.26In0.74; MgCu2-type, space group Fd 3 ¯ m; a = 7.556(1) Å for ErMn1.85In0.15. The positions of the Mg atoms in the Laves phase structures are occupied by rare-earth atoms, and the positions of the small atoms (Cu or Zn) are occupied by a statistical mixture of Mn and In atoms. The unit cell expands by the In substitution, and crossing the critical limit for the Mn–Mn spacing can allow the formation of Mn moments. This can contribute to the magnetic randomness and presumably glassy behaviour.