Atomic Layer Engineering of Perovskite Oxides for Chemically Sharp Heterointerfaces

摘要

The two-dimensional (2D) conducting interface between LaAlO_3 (LAO) and SrTiO_3 (STO)-both perovskite oxide band insulators-has attracted immense attention since its discovery by Ohtomo and Hwang.[1] Several unexpected physical properties have been experimentally observed,[2,3l which stimulated numerous theoretical investigations.[4-6] However, despite intense research, the exact origin of such remarkable behavior remains to be understood. While the polar catastrophe model at the interface between a polar (LAO) and a nonpolar (STO) oxide provides an appealing explanation for the characteristics of this system,[7] the role of extrinsic factors such as oxygen vacancies and/or cation intermixing in producing similar behavior cannot be ruled out.[8-15]