On-site Coulomb energy versus crystal-field splitting for the insulator-metal transition in La1-xSrxTiO3 -: art. no. 104420

The on-site Coulomb energy (U-dd) and crystal-field splitting (10Dq) of doped Mott-insulator La1-xSrxTiO3 have been estimated using resonant soft-x-ray emission spectroscopy (SXES). The Raman scattering of the e(g)- and t(2g)-resonant SXES spectra indicate features due to the d-d transitions corresponding to the 10Dq and U-dd/2, respectively. The U-dd is in accord with the energy separation between the lower and the upper Hubbard bands obtained by photoemission and inverse-photoemission spectra. The U-dd does not change much around two metal-insulator transitions at x=0.05 and 0.95 in La1-xSrxTiO3, while the crystal-field splitting increases as a function of x.