On the Origin of the 2DEG Carrier Density at the LaAlO$_3$/SrTiO$_3$   Interface
  Transport measurements of the two-dimensional electron gas (2DEG) at the LaAlO$_3$/SrTiO$_3$ interface have found a density of carriers much lower than expected from the "polar catastrophe" arguments. From a detail density-functional study, we suggest how this discrepancy may be reconciled. We find that electrons occupy multiple subbands at the interface leading to a rich array of transport properties. Some electrons are confined to a single interfacial layer and susceptible to localization, while others with small masses and extended over several layers are expected to contribute to transport. 
Zoran S. Popovi\'c, Sashi Satpathy, Richard M. Martin