Abstract
An orbital degree of freedom in Mott insulators gives strong impact on their phase transitions induced by the band-filling control or carrier doping. We have investigated the effect of electrostatic carrier doping on the electronic spectra for a layered Mott insulator SrMnO to reveal orbital-specific optical transitions. SrMnO is an -type Mott insulator and its conduction band is composed of nearly degenerated orbitals and . The charge modulation spectra for a rectifying SrMnO/Nb-doped SrTiO junction clearly revealed an optical transition at 1.7 eV, while a linear absorption spectrum is dominated by a transition at 2.0 eV. These are assigned to the transitions from O 2 to Mn and to , respectively. The accumulated charges with a density as high as 810 cm selectively occupy the nearly localized orbitals that hardly contribute to charge transport.
- Received 26 March 2012
DOI:https://doi.org/10.1103/PhysRevB.86.125127
©2012 American Physical Society