Remote hole-doping of Mott insulators on the nanometer scale
  At interfaces between polar and nonpolar perovskite oxides, an unusual electron-doping has been previously observed, due to electronic reconstructions. We report on remote hole-doping at an interface composed of only polar layers, revealed by high-resolution hard x-ray core-level photoemission spectroscopy. In LaAlO3/LaVO3/LaAlO3 trilayers, the vanadium valence systematically evolves from the bulk value of V3+ to higher oxidation states with decreasing LaAlO3 cap layer thickness. These results provide a synthetic approach to hole-doping transition metal oxide heterointerfaces without invoking a polar discontinuity. 
M. Takizawa, Y. Hotta, T. Susaki, Y. Ishida, H. Wadati, Y. Takata, K.   Horiba, M. Matsunami, S. Shin, M. Yabashi, K. Tamasa...