Effect of rare-earth doping in RCrSb₃ (R=La, Pr, Sm, and Gd)

We report on the electrical resistivity and magnetic susceptibility of La or Gd doped RCrSb₃ (R=La, Pr, Sm, and Gd). Single crystals were grown by increasing the nominal dopant by 25%. In general, two magnetic ordering transitions are found, T_c1 is attributed to ferromagnetic ordering of the itinerant Cr sublattice, and, at lower temperatures, T_c2 is attributed to ordering of the localized rare-earth sublattice. Alloying on the rare-earth site varies the de Gennes factor, DG=(g–1)²J(J+1), and dT_c1/d(DG)=–2  K, while dT_c2/d(DG)=5  K. These ordering temperatures are found to converge at GdCrSb₃, where a single ferrimagnetic transition is found at T_c2=86  K due to an antialignment of the itinerant Cr magnetic sublattice and the localized rare-earth magnetic sublattice. Initially, for DG<3.5, the two magnetic sublattices order in a ferromagnetic ground state, and the paramagnetic Weiss temperature decreases at the same rate as T_c1. But for DG>4.5, the rare-earth magnetic sublattice antialigns with respect to the Cr sublattice, and the Weiss temperature decreases five times as fast. In the region between (3.5<DG<4.5), a first-order phase transition is found at T_c2.

©2006 The American Physical Society