  Heterostructures of transition metal oxides (TMO) perovskites represent an
ideal platform to explore exotic phenomena involving the complex interplay
between the spin, charge, orbital and lattice degrees of freedom available in
these compounds. At the interface between such materials, this interplay can
lead to phenomena that are present in none of the original constituents such as
the formation of the interfacial 2D electron system (2DES) discovered at the
LAO3/STO3 (LAO/STO) interface. In samples prepared by growing a LAO layer onto
a STO substrate, the 2DES is confined in a band bending potential well, whose
width is set by the interface charge density and the STO dielectric properties,
and determines the electronic band structure. Growing LAO (2 nm) /STO (x
nm)/LAO (2 nm) heterostructures on STO substrates allows us to control the
extension of the confining potential of the top 2DES via the thickness of the
STO layer. In such samples, we explore the dependence of the electronic
structure on the width of the confining potential using soft X-ray ARPES
combined with ab-initio calculations. The results indicate that varying the
thickness of the STO film modifies the quantization of the 3d t2g bands and,
interestingly, redistributes the charge between the dxy and dxz/dyz bands.
