Hall effect in Ce 1-x Y x/Pd 3 mixed-valence alloys

Mixed-valence and Kondo lattice systems exhibit large anomalous Hall coefficients with a striking change of sign at low temperature in severa! systems (CePd3, CeCu6, ... , etc.). We have studied the Hall effect of Ce1-x YxPd3, in which the substitution of small amounts of Y for Ce prevents the development of coherence at low temperature. We find that the Hall coefficient does not change its sign at low temperature and can be well understood in the one-impurity model of Ramakrishnan, Coleman, and Anderson. We infer that the change of sign observed in CePd3 is an effect of coherence