Nuclear magnetic resonance investigation of the novel heavy fermion system Ce$_{2}$CoAl$_{7}$Ge$_{4}$

We present nuclear magnetic resonance (NMR) measurements performed on single crystalline Ce$_{2}$CoAl$_{7}$Ge$_{4}$. This material is a member of a recently discovered family of heavy fermion materials Ce$_{2}$MAl$_{7}$Ge$_{4}$, where M $=$ Co, Ir, Ni, or Pd that crystallize in the noncentrosymmetric tetragonal space group P4 -21m. Previous measurements indicated a strong Kondo interaction, as well as magnetic ordering at 1.75 K. Our $^{59}$Co NMR spectral measurements reveal a Knight shift anomaly at T* \textasciitilde 17.5 K for H$_{0}$ \textbar \textbar c, and 12.5 K for H$_{0}$ \textbar \textbar a associated with f-electron conduction electron coherence. Spin-lattice relaxation rate measurements indicate diverging spin fluctuations at a magnetic ordering temperature of 1.6 K. An analysis of the Korringa enhancement factor suggests that the character of the spin fluctuations is dominantly ferromagnetic.