Phase Separation from Electron Confinement at Oxide Interfaces

Oxide heterostructures are of great interest for both fundamental and applicative reasons. In particular,the two-dimensional electron gas at the LaAlO3=SrTiO3or LaTiO3=SrTiO3interfaces displays manydifferent properties and functionalities. However, there are clear experimental indications that the interfaceelectronic state is strongly inhomogeneous and therefore it is crucial to investigate possible intrinsicmechanisms underlying this inhomogeneity. Here, the electrostatic potential confining the electron gas atthe interface is calculated self-consistently, finding that such confinement may induce phase separation, toavoid a thermodynamically unstable state with a negative compressibility. This provides a robustmechanism for the inhomogeneous character of these interfaces