$4f$-Virtual-Bound-State Formation in Ce${\mathrm{Al}}_3$ at Low Temperatures

Specific-heat and electrical-resistivity measurements in Ce${\mathrm{Al}}_3$ below 0.2 K reveal enormous magnitudes of the linear specific-heat term $C=\gamma T$ ($\gamma =1620\mathrm{}$ mJ mole/${\mathrm{K}}^2$) and the $T^2$ term in $\rho =A{T}^2$ ($A=35\mathrm{}$ μΩ cm/${\mathrm{K}}^2$). We conclude that the $4f$ electrons obey Fermi statistics at low temperatures because of the formation of virtual bound $4f$ states.