Evidence of a heavy fermion state in the disordered Ce-alloy system without translation symmetry

We have measured the specific heat Cp and the resistivity ρ on sputtered amorphous Cex Y80-x Mn20 alloys. The low-temperature specific heat has been found to follow Cp =γT+β T3 for all the samples. The T -linear coefficient γ increases linearly with increasing Ce concentration and becomes very large (γ>100mJ mol-1 K-2) in the Ce-rich region. The γCe per Ce atom is about 200mJ Ce-mol-1 K-2 and almost independent of the Ce concentration. The large γCe has been interpreted in terms of the electronic specific heat owing to the 4f -electron mixed with conduction electrons. In the resistivity ρ, the -logT dependence has been observed at low temperature for x51, which suggests the formation of the dense Kondo state. The ρ vs T for x62 exhibits a maximum and decreases as ρA T2 with a large coefficient A down to the low-temperature limit. These results suggest the formation of a heavy fermion state as the ground state for x62. We made the Kadowaki-Woods (KW) plot for x62 and found the A/ γ2 value to be much smaller than that of the conventional KW relation probably due to the f -orbital degeneracy.