When the interface between oxide insulators becomes conducting

The state formed at the interface between two materials often offers unique and exciting properties. For instance, modern electronics is heavily based on such interfaces. A decade ago, a new conducting interface was discovered between the two insulating materials LaAlO₃ and SrTiO₃. The interface was soon found to host many interesting properties including superconductivity, magnetism, resistive switching and the possibility to easily create nanowires at the interface. This spurred a lot of interest in the system, but despite the extensive research, fundamental questions remains such as what the origin of the emergent properties is, and how appealing interface properties can be found and tailored.
Here, we show that replacing LaAlO₃ with different complex oxide films opens up new avenues to answer these questions. By the right choice of substitutes for LaAlO₃, one can end up with heterostructures where the origin of the interface conductivity is unambiguous and simple. In addition, more perfect heterostructures can be synthesized, giving rise to e.g. enhanced electron mobility and the emergence of quantum magnetotransport properties at low temperatures.