Electronic conduction at the interfaces of complex oxide heterojunctions

Abstract

Recently, the novel electronic properties of the heterointerfaces of metal oxides, created by means of atomic-scale epitaxy and advanced nano-characterization techniques, have been attracting much attention. This is because electronic states, distinct from those of bulk materials, induce intriguing properties that cannot be realized in conventional compound semiconductors. For example, it has been revealed that a superconducting state and ferromagnetism coexist at the interface between LaAlO₃ and SrTiO₃, whereas the ground states in bulk materials are nonmagnetic and insulating. Also, strongly correlated effects have been observed for a fractional quantum-Hall state at the ZnO/MgZnO interface. We briefly review the electronic properties and phenomena observed at these interfaces and related materials.