Low-Temperature Magnetic Properties of Several Compounds in Ce-Pd-X (X=Si, Ge and Al) Ternary Systems

We have investigated several ternary compounds of cerium in the Ce-Pd-X (X=Si, Ge and Al) systems and their La counterparts by measuring the magnetic susceptibility, electrical resistivity and specific heat. The Ce ions in these compounds are in the nearly trivalent state and most of them show magnetic order of either long-range or spin-glass type at low temperatures. None of them distinctly exhibits the heavy fermion behavior, although it may be obscured by atomic disorder in some compounds. The relation between several isostructural ternary compounds of Ce-Pd-(Si and Ge) or Ce-Pd-(Al and Ga) system is qualitatively discussed in the framework of the Doniach phase diagram. The variation of the unit cell volume suggests that the former group is consistent with this phase diagram but the latter is not seemingly so. We found that LaPdSi 3 and LaPd 0.6 Ge 1.4 among the La counterparts are superconducting below 2.6 and 2.8 K, respectively.