Nature of the apical and planar oxygen bonds in the Srn+1RunO3n+1 family (n=1,2,3)

We investigate the electronic structure of the Srn+1RunO3n+1 family (n=1,2,3) in the vicinity the Fermi level by means of polarization-dependent resonant O 1s x-ray emission spectroscopy. Using both energy window and polarization analysis we disentangle the contribution of apical and planar oxygen, and compare it with first-principles calculations. Our results provide a new insight on the nature of the oxygen bonds and the role of Sr 3d states.