Structure and magnetism of the RTiFe11 compounds (R=Gd, Tb, Dy, Ho and Er)

Ternary alloys of the composition RTiFe₁₁ (R=Gd, Tb, Dy, Ho and Er) were prepared and investigated. The samples were found to be nearly single-phase materials, with small amounts of extraneous phases appearing primarily along the grain boundaries. The Curie temperatures were observed to be in the range 502 to 603 K and to vary with the R component according to the square root of the de Gennes function, reflecting the R-Fe exchange interaction. All of the compounds studied, except TbTiFe₁₁, possess uniaxial anisotropy at room temperature. The results obtained indicate that the R and Fe sublattices couple in an antiparallel manner, as is normally the case in heavy rare-earth-transition-metal compounds. A first-order magnetization process (FOMP) was observed in the Dy and Ho compounds, but not in their Gd and Er analogs. In the case of the Tb compound, there were some indications of the FOMP, but it was not nearly as pronounced as in the case of the Dy- and Ho-based compounds. The M versus T curves provide strong evidence of spin reorientations in the systems containing Tb, Dy, and Ho. AC susceptibility studies suggest the presence of a spin reorientation in the Er compound