Two-Dimensional Confinement of 3d1 Electrons in LaTiO3/LaAlO3 Multilayers

摘要

We report spectroscopic ellipsometry measurements of the anisotropy of the interband transitions parallel and perpendicular to the planes of (LaTiO3)n(LaAlO3)5 multilayers with n=1–3. These provide direct information about the electronic structure of the two-dimensional (2D) 3d1 state of the Ti ions. In combination with local density approximation, including a Hubbard U calculation, we suggest that 2D confinement in the TiO2 slabs lifts the degeneracy of the t2g states leaving only the planar dxy orbitals occupied. We outline that these multilayers can serve as a model system for the study of the t2g 2D Hubbard model.