guide to engineering transition metal oxide heterointerfaces.'
author:
- 'Hanghui Chen$^{1,3}$ Alexie Kolpak$^{2,3}$ and Sohrab Ismail-Beigi$^{1,2,3}$'
bibliography:
- 'sto-lao-long-prb11.bib'
title: 'A First-Principles Study of the Electronic Reconstructions of $\textrm{LaAlO}_3/\textrm{SrTiO}_3$ Heterointerfaces and Their Variants'
---

Introduction
============

With the advance of techniques to control thin film growth on the atomic scale, the study of epitaxial oxide heterostructures is a rapidly developing area of materials science [@Dagotto-Science-2007]. Due to the ability to produce a well-defined single terminated substrate surface [@Kawasaki-Science-1994], interfaces that are nearly atomically sharp can be formed. In many cases, the properties of these interfaces turn out to be much richer than those of the bulk constituents. One of the most interesting examples is the (001) interface between LaAlO$_3$ (LAO) and SrTiO$_3$ (STO), both constituents of which are conventional band insulators in the bulk. Among the intriguing phenomena observed at this interface is the presence of a high-mobility quasi two-dimentional electron gas [@Hwang-Nature-2004], which is sensitive to the LaAlO$_3$ film thickness on the nanoscale [@Mannhart-Science-2006; @Huijben-NatMat-2006; @Bell-APL-2009], and can be tuned via an external field [@Mannhart-Science-2006; @Triscone-Nature-2008]. In addition, both magnetism [@Brinkman-NatMat-2007] and superconductivity [@Mannhart-Science-2007] have been observed at LaAlO$_3$/SrTiO$_3$ interfaces.

Due to these interface properties, the LaAlO$_3$/SrTiO$_3$ system shows 