MAGNETIC-PROPERTIES OF THMN12-TYPE CECU4AL8 AND RELATED CE-COMPOUNDS - HEAT-TREATMENT EFFECTS

The magnetic properties of the ThMn12-type CeCu4Al8 have been investig ated by specific heat, magnetic susceptibility and electrical resistiv ity measurements. As we reported previously, CeCu4Al8 is of an incongr uent melt type. The specific heat for the CeCu4Al8 sample annealed at 700 degrees C (750 degrees C) showed a large jump (peak) at 5.8 K (4.3 K), indicating the antiferromagnetic transition (T-N), with a large C /T value of similar to 0.3 J/K-2 mol just above T-N and similar to 0.2 J/K-2 mol at T-->0 (heavy fermion antiferromagnet). The resistivity s howed a - log(T)-like increase below similar to 50 K and, after taking a gentle maximum at somewhat higher temperature than T-N, it decrease d rather rapidly below T-N with decreasing temperature. We have also i nvestigated magnetic properties of the ThMn12-type CeCr4Al8 and CeMn4A l8. The low-temperature specific heat showed large C/T of 0.18 J/K-2 m ol for CeCr4Al8 and 0.25 J/K-2 mol for CeMn4Al8, without any magnetic ordering. (C) 1998 Elsevier Science B.V. All rights reserved.