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

We use photoemission (PE) and x-ray absorption (XA) spectroscopy to study i ntercalation-induced changes in the electronic structure of beta -HfNCl and Na0.22HfNCl. PE shows appearance of new states in Na0.22HfNCl within the g ap of beta -HfNCl, with negligible changes in the energy positions of valen ce-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-dim ensional character, extends to lower energy in Na0.22HfNCl than in beta -Hf NCl. The study provides information on the electronic structure and its cha nge across the insulator-to-metal transition of the. new class of supercond uctors.