SPECIFIC-HEAT AND HEAVY-FERMIONIC BEHAVIOR IN CE8PD24M (M = GA, IN, SN, SB, PB, AND BI)

Specific-heat measurements have been carried out to further elucidate the electronic and magnetic properties of Ce8Pd24M (M=Ga, In, Sn, Sb, Pb, and Bi). The measurements show that a slight change in the chemica l and electronic structure of CePd3, by forming the ordered ternary Ce 8Pd24M-type compounds, induces an enhanced low-temperature electronic specific heat gamma. This indicates the emergence of heavy-fermionic b ehavior with the loss of the intermediate valence nature of CePd3. All of the Ce8Pd24M-type compounds studied here exhibit a sharp peak in t he specific heat at low temperature due to antiferromagnetic (AF) tran sitions. Below the transition temperature, the specific heat shows the heavy-fermionic behavior, i.e., gamma( T-->0) equal to a finite value , rather than gamma( T-->0)=0 in the paramagnetic AF ground state.