LOW-TEMPERATURE MAGNETIZATION STUDY OF THE HEAVY-ELECTRON SYSTEMS

The ground-state magnetic properties of Ce0.75La0.25B6 and Sm3Te4 have been studied by means of static magnetization measurements at very lo w temperatures T greater than or equal to 50 mK. In Ce0.75La0.25B6, th e H-T phase diagram reveals three different ordered phases: in additio n to the two phases (phase II and III) known for CeB6, a new antiferro magnetic state appears before the antiferro-quadrupolar order sets in. In the valence fluctuation compound Sm3Te4, a spin-glass ordering is evidenced at T-g similar to 1.3 K. It is likely that the two valence s tates (Sm2+, Sm3+) are randomly frozen at low temperature to form effe ctively a randomly diluted magnet.