Comparative Study of Magnetic Phase Diagrams of Ce Compounds

概要

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Thermal properties of magnetically ordered Ce-lattice systems are compared in their crossover to the non-magnetic state, driven by alloying effects. The ordering temperature (T ord=T N or T C) is found to go to zero continuously only in a few cases, while in others a discontinuity in its decrease is clearly observed. Coincidentally, the magnetic contribution to the specific heat (Cp), the entropy and the free energy variations with temperature mark an evident difference between those cases. Furthermore, the extension of the non-Fermi-liquid (NFL) phase in terms of concentration variation correlates with differences observed in the respective ordered phase.A systematic transformation from a mean field like transition to a fluctuation dominated type is observed in Cp(T), as the system overcomes a characteristic crossover concentration. Such a concentration appears as a limit for the NFL behavior in the paramagnetic phase above T ord. A possible origin of the mentioned differences are discussed in terms of some alternatives in the evolution of the magnetic moments and the strength of their interactions.
1998-05-15