Spectroscopic investigation on the electronic structure of a 5$d$ band insulator SrHfO$_{3}$

We investigated the high-energy electronic structure of a 5d perovskite SrHfO$_{3}$. By using optical spectroscopy and O 1$s$ x-ray absorption spectroscopy, the values of electronic structure parameters are estimated properly. In particular, the crystal field splitting energy, which is closely associated with the $p-d$ hybridization strength, is as high as 5 eV, and the Sr 4$d$ bands appear to be strongly mixed with the Hf 5$d$ bands. Moreover, the emission spectra with a 325 nm light excitation exhibit a sizable strength near 500 nm at low temperatures due to oxygen defects. These findings in SrHfO$_{3}$ are compared with electronic properties of similar compounds, 3$d$ SrTiO$_{3}$ and 4$d$ SrZrO$_{3}$.