On the Origin of the 2DEG Carrier Density at the LaAlO${}_3$/SrTiO${}_3$ Interface

Abstract

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.

4 pages, 7 figures, Accepted in Phys. Rev. Lett