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

TL;DR

This study investigates the electronic structure of LaTiO3/LaAlO3 multilayers, revealing 2D confinement effects on Ti 3d electrons and providing insights into the t_{2g} orbital behavior relevant for Hubbard model studies.

Contribution

It combines spectroscopic ellipsometry with LDA+U calculations to demonstrate 2D confinement of Ti 3d electrons and orbital degeneracy lifting in multilayers.

Findings

2D confinement lifts t_{2g} degeneracy

Only planar d_xy orbitals are occupied

Multilayers serve as a model for 2D Hubbard systems

Abstract

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) 3d^1 state of the Ti ions. In combination with LDA+U calculations, we suggest that 2D confinement in the TiO2 slabs lifts the degeneracy of the t_{2g} states leaving only the planar d_xy orbitals occupied. We outline that these multilayers can serve as a model system for the study of the t_{2g} 2D Hubbard model.