Manifestation of lattice distortions in the O 1s spectra in Ca_1-xSr_xRuO₃

Abstract

We investigate the effect of temperature on the electronic and crystal structures of Ca_1-xSr_xRuO₃ via the evolution of O 1s core level spectra as a function of temperature and composition, x. O 1s spectra of SrRuO₃ exhibit a dominant sharp feature at all the temperatures with a small trace of an impurity feature at higher binding energies. The spectra of Ca doped samples, however, exhibit two distinct features. Analysis of the experimental spectral functions and the band structure results suggest that the different Madelung potentials at the two kinds of oxygen sites in the orthorhombically distorted structure lead to two distinct features in the O 1s spectra. Interestingly, the energy separation of these two features becomes smaller at low temperatures for the Ca dominated samples concomitant to the observation of non-Fermi liquid behavior in their bulk properties. Such temperature evolution, thus, indicates a direct connection of the lattice degrees of freedom with the electronic properties of these compounds.