Optical spectroscopy and ultrafast pump-probe studies on the heavy fermion compound CePt$_2$In$_7$

We report optical spectroscopy and ultrafast pump-probe measurements on the antiferromagnetic heavy fermion compound CePt$_2$In$_7$, a member showing stronger two dimensionality than other compounds in CeIn$_3$-derived heavy-fermion family. We identify clear and typical hybridization spectral structures at low temperature from the two different spectroscopy probes. However, the strength and related energy scale of the hybridization are much weaker and smaller than that in the superconducting compounds CeCoIn$_5$ and CeIrIn$_5$. The features are more similar to observations on the antiferromagnetic compounds CeIn$_3$ and CeRhIn$_5$ in the same family. The results clearly indicate that the Kondo interaction and hybridizations exist in the antiferromagnetic compounds but with weaker strength.