Magnetoresistance behaviour of the ternary stannides CeNi0.86Sn2 and Ce3Ni2Sn7

In order to obtain more information on the magnetic phase diagram of these stannides, we have performed magnetization and magnetoresistance (MR) measu rements. The results are summarized as follows: (i) in the paramagnetic ran ge, the negative curvature of the MR = f(mu H-0) curve for CeNi0.86Sn2 refl ects the existence of Kondo interactions; for T <8 K, a change of regime ap pears reminiscent of the onset of ferromagnetic ordering showing that the a ntiferromagnetic structure of this stannide became easily ferromagnetic und er low applied fields; (ii) MR of Ce3Ni2Sn7 is positive for T > 12 K then c hanges sign showing that the Kondo effect is rather small for T < 12 K: bel ow 7 K MR becomes more negative with decreasing temperature confirming the metamagnetic transition observed at low fields by magnetization measurement s. (C) 2001 Elsevier Science B.V. All rights reserved.