Comparison of valence bands of LaAlO3/SrTiO3 samples of varying thickness.
The energy alignment is carried out using the L3 resonance enhancement (see insets). The shift of the leading edge for increasing layer thickness corresponds to an upshift of the LaAlO3 part (see text for details). The binding energy scale has been set manually to match a valence band maximum of the 1 u.c. LaAlO3 of EB ≃ 4eV.