Revisiting the heavy-fermion compound ${\mathrm{YbCdCu}}_4$: Kondo temperature and the ground-state degeneracy

${\mathrm{YbCdCu}}_4$ has been characterized as a heavy-fermion Kondo lattice system without long-range magnetic order. Thermodynamic and transport data of this compound have been partially analyzed, and the reported Kondo temperatures $T_K$ are highly dependent on samples and estimation methods. In particular, the magnetic susceptibility $\chi \left(T\right)$ of this compound does not show the maximum corresponding to the Kondo resonance with a large degeneracy of the ground state, partly due to the sample quality. Thus, single crystals of ${\mathrm{YbCdCu}}_4$ are grown to reinvestigate their physical properties by means of magnetization, specific heat, electrical resistivity, Hall resistivity, and thermoelectric power measurements. Unlike earlier studies, we found consistencies regarding the $T_K\sim 160$ K measurement estimated from thermodynamic and transport property measurements. The magnetic part of the specific heat $C_m$ displays a broad maximum near 70 K, which follows well with the prediction made by the Coqblin-Schrieffer (C-S) model for whole $J=7/2$ multiplets involved in the formation of the Kondo state. However, the local maximum in $\chi \left(T\right)$ does not match well with the C-S model prediction due to the crystalline electric field (CEF) effect, where the $T_K$ value is still greater than the overall CEF splittings: $T_K>{\Delta }_{CEF}$. Electrical resistivity and Hall coefficient measurements indicate an extremum near $\sim 70$ K, while a negative minimum at $\sim 130$ K is observed in thermoelectric power.