Evolution of lattice coherence in the intermediate-valence heavy-fermion compound Eu Ni 2 P 2 studied by point contact spectroscopy

We performed a point contact spectroscopy study in an intermediate-valence heavy-fermion (HF) compound $\mathrm{Eu}{\mathrm{Ni}}_{2}{\mathrm{P}}_{2}$. Above the Kondo temperature ${T}_{\mathrm{K}}$, the differential conductance spectra show a broad peak due to the Kondo resonance at the Eu site. Below ${T}_{\text{K}}$, the broad peak splits into two peaks that can be reproduced by the summation of two Fano curves with the same parameters, indicating the emergence of the indirect hybridization gap in an Anderson lattice. With decreasing temperature, the separation between the two peaks increases and saturates at very low temperatures. The results reveal the evolution of the electronic structure in the HF state due to the development of the lattice coherence.