We present experimental photoemission and inverse photoemission spectra of SrTiO3−δ representing electron doped d0 systems. Photoemission spectra in presence of electron doping exhibit prominent features arising from electron correlation effects, while the inverse photoemssion spectra are dominated by spectral features explainable within single-particle approaches. We show that such a spectral evolution in chemically doped correlated systems is not compatible with expectations based on Hubbard or any other similar model. We present a new theoretical approach taking into account the inhomogeneity of the `real' system which gives qualitatively different results compared to standard `homogeneous' models and is in quantitative agreement with experiments.
@article{arxiv.cond-mat/9609259,
title = {Spectral functions in doped transition metal oxides},
author = {D. D. Sarma and S. R. Barman and H. Kajueter and G. Kotliar},
journal= {arXiv preprint arXiv:cond-mat/9609259},
year = {2016}
}