COHERENT KONDO-LATTICE GROUND-STATE IN CENI0.85RH0.15SN ALLOY

We have carried out structural, magnetic and transport measurements on CeNi0.85T0.15Sn (T=Ni, Ru, Ph and Pd) alloys in order to understand t he complex low-temperature transport properties of the Kondo semicondu ctor CeNiSn. The resistivity measurements show that the observed low-t emperature rise in the resistivity of CeNiSn becomes less pronounced w ith Ru and Pd substitution. Further, the resistivity of CeNi0.85Rh0.15 Sn alloy shows the onset of the coherent Kondo-lattice ground state be low 18 K and exhibits a T-2 behaviour below 7 K. The observed large ne gative magnetoresistance in CeNiSn at 1.7 K suggests that the energy g ap decreases as the magnetic field increases. Positive magnetoresistan ce is observed in LaNiSn and CeNiSn at high temperatures and high fiel ds. The negative magnetoresistance of CeNi0.85T0.15Sn (T=Rh and Pd) al loys exhibits a scaling behaviour as proposed by Schlottmann for singl e ion Kondo impurity. CeNi0.85Rh0.15Sn alloy exhibits positive magneto resistance at 2 K and negative minimum magnetoresistance at 5 K, which further confirms the presence of a coherent Kondo-lattice ground stat e. The susceptibilities of all these alloys exhibit Curie-Weiss behavi our in the high-temperature regime. (C) 1998 Elsevier Science S.A.