Changes of electronic structure across the insulator-to-metal transition of quasi-two-dimensional Na-intercalated β-HfNCl studied by photoemission and x-ray absorption -: art. no. 153107

We use photoemission (PE) and x-ray absorption (XA) spectroscopy to study intercalation-induced changes in the electronic structure of beta -HfNCl and Na0.22HfNCl. PE shows appearance of new states in Na0.22HfNCl within the gap of beta -HfNCl, with negligible changes in the energy positions of valence-band features of the parent, suggesting a non-rigid-band behavior. N 1 s,XA results show that the tail of the conduction band, with a quasi-two-dimensional character, extends to lower energy in Na0.22HfNCl than in beta -HfNCl. The study provides information on the electronic structure and its change across the insulator-to-metal transition of the. new class of superconductors.