Electronic structure of CeNi${}_{1-x}$Pd${}_x$Sn and La$M$Sn $(M$=Ni,Cu,Pd)

The electronic structure of CeNi${}_{1-x}$Pd${}_x$Sn has been studied by photoemission spectroscopy. CeNiSn belongs to the class of Kondo insulating materials. The gap formed at the Fermi level is strongly suppressed by substituting Pd for Ni. The x-ray photoemission spectroscopy (XPS) valence band spectra can be compared with ab initio electronic-structure calculations using the linearized muffin-tin orbital (LMTO) method. We have found a small indirect gap and a low density of states at the Fermi energy for CePdSn. The 3$d$ XPS spectra and LMTO calculations indicate a strong hybridization of the $f$ orbitals with conduction band and the interatomic hybridization which causes the large charge transfer between atoms. We have also observed the correlation between the electronic structure near Fermi energy and the crystallographic properties of the alloyed CeNiSn. We also present the electronic structures of LaNiSn, LaCuSn, and LaPdSn. These compounds are good reference for CeNiSn. At Fermi energy a relatively low density of states is found, for LaCuSn an indirect gap is formed. The metallic samples show a relatively high resistivity at room temperature, the largest for LaCuSn, which demonstrates the influence of the gap on the electric transport properties.