ANOMALOUS BEHAVIOR IN RARE-EARTH AND ACTINIDE SYSTEMS

摘要

Many different anomalous behaviours (intermediate valence, heavy fermions, competition between magnetic order and Kondo effect) have been experimentally observed in alloys and compounds containing anomalous rare-earths, Ce, Yb, Eu and also Pr, Sm and Tm, as well as in systems with non-magnetic actinides U, Np and Pu. This paper reviews theoretical models describing several interesting cases: the transitions accompanied by a valence change such as for example in cerium metal and Eu(Pd_(1-x)Au_x)2Si_2 alloys; the "normal" Kondo effect and the heavy fermion behaviour; the "underscreened" Kondo effect which can be applied to actinide compounds; the occurrence of antiferromag-netic, Kondo, Non Fermi Liquid and spin glass phases in cerium or uranium disordered alloys.