Magneto-resistance studies on RTSb2 compounds (R=La, Ce and T=Ni, Cu)

The RTSb2 (R=La, Ce and T=Ni, Cu) compounds crystallize in the tetragonal ZrCuSi2 type structure (space group P4/nmm). Magnetic measurements indicate that CeNiSb2 orders ferromagnetically at 6 K while CeCuSb2 orders antiferromagnetically at 5 K. The electrical resistivity of the two La analogs, LaCuSb2 and LaNiSb2 show normal metallic behaviour down to 5.4 K with no superconducting transition. The resistivity of both the Ce-compounds show broad minimum typical of Kondo lattice systems. There is a low temperature drop in resistivity in both the compounds due to magnetic ordering. However, in CeNiSb2 a second minima (at 10 K) followed by a maximum at 6 K is also observed. Magneto-resistance (MR) is positive for all the compounds except CeNiSb2 in the temperature range 4.5-1.5 K in fields up to 45 kOe. However, CeNiSb2 shows negative MR due to the ferromagnetic ordering. (orig.)