Effect of Kondo-lattice coherence on the phononic and electronic excitations of CeCoIn$_{5}$

Heavy fermion metal CeCoIn$_{5}$ has a coherence temperature T*$=$45K, below which individual Kondo singlets evolve into a coherent Kondo lattice [P. Coleman, \textit{Introduction to Many-Body Physics} (Cambridge University Press, 2015)]. We study the phononic and electronic excitations of this compound by inelastic light scattering. Two optical phonon modes exhibit anomalies in their temperature dependence of frequency and linewidth below T*. Such anomalous behaviors result from developing coherent spectral weight at the Fermi level and reducing electron-phonon scattering rate. Moreover, below T* the B$_{2g}$-symmetry electronic excitations are suppressed up to 50cm$^{-1}$; the suppressed Raman response follows a cubic power law. These results support T* as the characteristic temperature marking the development of Kondo-lattice coherence.