Anomalous specific heat ofCe1−xThxRhSb alloys

Low-temperature specific heat and magnetic susceptibility for ${\mathrm{Ce}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Th}}_{\mathit{x}}$RhSb alloys, 0≤x≤0.6, have been investigated. CeRhSb, identified previously as a Kondo insulator, has C/T>30 mJ/${\mathrm{K}}^2$ mol at T→0 K. Above 6 K, C/T is proportional to ${\mathit{T}}^2$ yielding a high-temperature γ of 90 mJ/${\mathrm{K}}^2$ mol. Th substitution for Ce causes large, but non-Kondo-like enhancement of the specific heat. Alloys corresponding to 0.3≤x≤0.4 belong to the heaviest Ce-based heavy fermions.