  Quantum-mechanical fluctuations in strongly correlated electron systems cause
unconventional phenomena such as non-Fermi liquid behavior, and arguably high
temperature superconductivity. Here we report the discovery of a field-tuned
quantum critical phenomenon in stoichiometric CeCu2Ge2, a spin density wave
ordered heavy fermion metal that exhibits unconventional superconductivity
under ~ 10 GPa of applied pressure. Our finding of the associated quantum
critical spin fluctuations of the antiferromagnetic spin density wave order,
dominating the local fluctuations due to single-site Kondo effect, provide new
information about the underlying mechanism that can be important in
understanding superconductivity in this novel compound.
