Manifestation of ground state anomaly in the core level spectra of Ca and Sr in Ca(1-x)SrxRuO3

We investigate the evolution of Ca 2p and Sr 3d core level spectra in Ca(1-x)SrxRuO3 using photoemission spectroscopy. Core level spectra in this system exhibit multiple features and unusual evolution with the composition and temperatures. Analysis of the core level spectra in conjunction with the band structure results reveal novel final state effects due to different core hole screening channels. Changes in the core level spectra suggest significant modification in Ca-O covalency in Ca dominated samples, which gradually reduces with the increase in Sr content and becomes minimum in SrRuO3. This study thus, provides a direct evidence of the role of cation-oxygen covalency in the ground state properties of these novel materials.