Crystal growth and magnetic behavior of R6T13−xAlxMy phases (R=La, Nd; T=Mn, Fe; M=main group) grown from lanthanide-rich eutectic fluxes

Binary eutectic mixtures of early lanthanide metals and late transition metals have been explored as media for crystal growth of new intermetallic phases. A large family of R₆T_13−xAl_xM_y phases (R=La or Nd; T=Fe or Mn; M=main group elements) with the La₆Co₁₁Ga₃ structure type can be crystallized from La/Ni and Nd/Fe eutectics. The tetragonal structure of these compounds features slabs of transition metal atoms capped with mixed T/Al sites and separated by layers of lanthanide ions. The growth of large crystals of the lanthanum analogs allows for the study of the anisotropic magnetic properties of the transition metal slabs. For La₆Fe_13−xAl_xM_y analogs, these order antiferromagnetically with T_N strongly dependent on the Fe/Al ratio on the mixed sites. Growth of Mn analogs is reported for the first time; the transition metal slabs in La₆(Mn/Ni)₁₀Al₃ phases order ferromagnetically with a T_C of 200 K.