The effect of in-plane strain on the electronic properties of LaAlO3/SrTiO3 interface

• The effect of in-plane strain on the LaAlO3/SrTiO3 interface is investigated.
• The roughness of the interface becomes larger with decreasing lattice constant.
• The interfacial Ti 3dxy electrons is the origin of the 2DEG formed at the interface.
• In-plane strain can tailor the 2DEG and induce a metal-insulator transition.

The density functional theory (DFT) calculations are employed to investigate the effect of in-plane strain on the lattice relaxation and electronic properties of LaAlO3/SrTiO3 interface. It is obtained that the in-plane strain influences the lattice relaxation obviously. The distortion of interfacial Ti–O octahedron is enhanced with the increasing of the in-plane compressive strain. The Ti 3dxy orbital at the interface is partly filled and it is the origin of the interfacial two-dimensional electron gas (2DEG). The in-plane strain can effectively modulate the carrier concentration and consequently the conductivity of the 2DEG formed at the interface. In-plane strain may reduce the carrier concentration significantly and induce a metal-insulator transition when the in-plane compressive (tensile) strain is added up to 4.98% (5.29%).