Suppression of heavy fermions by high fields inCeCu6

Measurement of the specific heat of ${\mathrm{CeCu}}_6$ in fields to 24 T between 1.8 and 8 K and of the magnetization in fields to 20 T at 1.3 and 4.2 K is reported. The value of γ (=C/T) in 24 T is 350 mJ/mol ${\mathrm{K}}^2$. The slope of the C/T-vs-$T^2$ data, proportional to the Debye temperature, in 24 T is the same as that for ${\mathrm{LaCu}}_6$ in zero field, with no low-temperature upturn in the C/T data in 24 T observed. These data indicate that we achieve complete suppression of the heavy-fermion ground state in ${\mathrm{CeCu}}_6$ with this high applied magnetic field. These results are in sharp contrast with results on uranium systems, indicating a fundamental difference in the heavy-fermion ground state. Implications for de Haas-van Alphen experiments are discussed.