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, TC1 is attributed to ferromagnetic ordering of the itinerant Cr sub-lattice, and, at lower temperatures, TC2 is attributed to ordering of the localized rare-earth sub-lattice. Alloying on the rare-earth site varies the de Gennes factor, DG = (g-1)2J(J+1), and dTC1/d(DG) = -2K, while dTC2/d(DG) = 5K. These ordering temperatures are found to converge at GdCrSb3, where a single ferrimagnetic transition is found at TC2 = 86 K due to an anti-alignment of the itinerant Cr moments and the localized rare-earth moments. Initially, for DG < 3.5, the rare-earth moments are found to align ferromagnetically, and the paramagnetic Weiss temperature decreases at the same rate as TC1. But for DG > 4.5, the rare-earth sub-lattice anti-alignes with respect to the Cr sub-lattice, 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 TC2