Magnetic properties of diluted band ferromagnet URhAl

Abstract

Crystal structure, magnetization, and specific-heat studies were performed on the ${\mathrm{U}}_{1-x}{\mathrm{Th}}_x\mathrm{RhAl}$ and ${\mathrm{U}}_{1-x}{\mathrm{Lu}}_x\mathrm{RhAl}$ pseudoternary systems. The parent URhAl compound orders ferromagnetically below $T_C=27\mathrm{}\mathrm{K}.$ Dilution of the U sublattice by Th or Lu leads to a rapid decrease of both the magnetic-ordering temperature and the spontaneous magnetic moment. The long-range magnetic order vanishes around 35% Th or 15% Lu substitution. The electronic specific heat shows a maximum in this critical concentration region.