MAGNETIC PHASE-DIAGRAM IN CEC2 ENCAPSULATED IN CARBON NANOCAGES

An experimental study of a magnetization process for CeC2 crystals enc apsulated in carbon nanocages, in the low temperature antiferromagneti c region (T < similar to 30 K) in magnetic fields up to 42 T, is repor ted. The magnetization curves M(H) show a dramatic change at a critica l field H-c( < similar to 3.5 T) with a significant hysteresis below 1 6 K. At a particular field, H-s( < 15 +/- 2 T), net magnetization leve ls off. The behavior at H-c is ascribed to a phase transition between an antiferromagnetic and a spin-flop state, and that at H-s is ascribe d to a phase transition between a spin-flop and a paramagnetic state. The magnetic phase diagram in the applied field and temperature plane is accurately determined based on the results of H-c(T) and H-s(T), an d on the cusp of M(T) curves at various fixed fields. (C) 1998 Elsevie r Science Ltd. All rights reserved.