The conducting interface of LaAlO 3/SrTiO 3 heterostructures has been studied by hard x-ray
photoelectron spectroscopy. From the Ti 2 p signal and its angle dependence we derive that
the thickness of the electron gas is much smaller than the probing depth of 4 nm and that the
carrier densities vary with increasing number of LaAlO 3 overlayers. Our results point to an
electronic reconstruction in the LaAlO 3 overlayer as the driving mechanism for the
conducting interface and corroborate the recent interpretation of the superconducting …

[en] Oxide heterostructures are of special interest due to unexpected new physics occurring
at the interface. One heavily discussed topic is the quasi-two-dimensional electron gas
(2DEG), which emerges at the interface of the two band insulators LaAlO 3/SrTiO 3, if at least
4 unit cells of LaAlO 3 are grown on TiO 2-terminated SrTiO 3. Moreover, both a magnetic
and a superconducting phase at low temperatures have been reported for the ground state
of the 2DEG. We have studied this buried interface by angle dependent hard X-ray …