Gapless band structure of PbPdO2: A combined first principles calculation and experimental study

摘要

We present experimental evidence of the gapless band structure of PbPdO_2 by combined x-ray photoemission and x-ray absorption spectra complemented with first principles band structure calculations. The electronic structure near the Fermi level of PbPdO_2 is mainly composed of O 2p and Pd 4d bands, constructing the conduction path along the Pd-O layer in PbPdO_2. Pd deficiency in PbPdO_2 causes decreased O 2p-Pd Ad and increased O 2p-Pb 6p hybridizations, thereby inducing a small band gap and hence reducing conductivity. Hall measurements indicate that PbPdO_2 is a p-type gapless semiconductor with intrinsic hole carriers transporting in the Pd-0 layers.