Two-Dimensional Electron Gases at LaAlO 3 / SrTiO 3 Interfaces: Orbital Symmetry and Hierarchy Engineered by Crystal Orientation

Recent findings show the emergence of two-dimensional electron gases (2DEGs) at LaAIO_3/SrTiO_3 interfaces along different orientations; yet details on band reconstructions have remained so far unknown. Via x-ray linear dichroism spectroscopy, we demonstrate that crystal symmetry imposes distinctive 2DEG orbital hierarchies on (001)-and (110)-oriented quantum wells, allowing selective occupancy of states of different symmetry. Such orientational tuning expands the possibilities for electronic engineering of 2DEGs and opens up enticing opportunities to understand the link between orbital symmetry and complex correlated states at LaAIO_3/SrTiO_3 quantum wells.