Valence band study of Ba1-xSrxRuO3(x = 0,0.2)

Electronic structure of polycrystalline BaRuO3 with 9R structure and Ba0.8Sr0.2RuO3 with 4H structure have been investigated using ultraviolet photoemission spectroscopy. Both the systems exhibit Fermi cut off at room temperature exhibiting metallic character. Comparison of experimental valence band spectra with available band structure calculations suggest weak/negligible electron correlation strength among these 4d transition metal oxides. Interestingly, 4H-Ba0.8Sr0.2RuO3 exhibits flat spectral density of states while 9R-BaRuO3 shows a dip at Fermi level indicating presence of a pseudogap.