Interplay of spin gap and nanoscopic quantum fluctuations in intermetallic CeCu2Ge2

Neutron scattering measurements are used to elucidate interplay of the field-induced spin gap and the quantum fluctuations in archetypal heavy electron system CeCu${}_2$Ge${}_2$. A spin gap of $\mathrm{\Delta }$ = 0.56 meV is found to develop near the field-induced quantum critical state at $H$${}_c$$\simeq$ 8 T, driven by fluctuations of the long range antiferromagnetic order parameter. The superconducting transition temperature in many magnetic superconductors is found to exhibit one-to-one correspondence with the spin gap. In this regard, the demonstration of an interplay of the spin gap with the nanoscopic dynamic correlation provides new arena to explore direct relation between the quantum critical behavior and the unconventional superconductivity, especially in heavy electrons systems.