We performed in situ angle-resolved photoemission spectroscopy measurements on ${\text{La}}_{2/3}{\text{Sr}}_{1/3}{\text{MnO}}_3$ thin and ultrathin films deposited onto ${\text{SrTiO}}_3$ substrates in order to determine their electronic band structure. We directly identified, in ultrathin films, an enhancement of the occupation of the out-of-plane $\text{Mn}3d{e}_g$ $\left(3z^2-r^2\right)$ band at the expense of the in-plane $3d{e}_g$ $\left(x^2-y^2\right)$ band. Such a disproportionate change in orbital occupation is interpreted as the origin of the strong depression of the magnetotransport properties at the interface between manganite films and substrates.

• Received 14 March 2010

DOI:https://doi.org/10.1103/PhysRevB.82.214407