Electrostatic doping into an n-type Mott insulator Sm2CuO4 has been successfully achieved with use of the heterojunction with an n-type band semiconductor Nb-doped SrTiO3. The junction exhibits rectifying current-voltage characteristics due to the interface band discontinuity and the formation of depleted region. The application of reverse bias electric field on this junction enables the field-effect electron doping (presumably up to 6% per Cu atom) to the Mott insulator. The electro-modulation absorption spectroscopy could clearly show a large modification of the Mott-gap state accompanying the spectral weight transfer to the lower-energy region, reminiscent of formation of a metallic state.
@article{arxiv.cond-mat/0702351,
title = {Optical probe of electrostatic doping in an n-type Mott insulator},
author = {M. Nakamura and A. Sawa and H. Sato and H. Akoh and M. Kawasaki and Y. Tokura},
journal= {arXiv preprint arXiv:cond-mat/0702351},
year = {2007}
}