From fundamentals to gap nanoengineering of high-Tc and related oxides

Complete understanding of fundamentals of a given class of electronic materials often produces successful new technology. In analogy with a successful (Al)GaAs band-gap engineering, I discuss an equivalent nanotechnology of high-Tc (and related) oxides. Controlled heteroepitaxy of layered oxides provides the opportunity to design the desired superconducting gap and/or insulating barrier. However, the progress is somewhat hindred by difficult local doping and non-homogeneous oxygen distribution in some oxides. I also briefly discuss puzzling electronic properties across the electronic phase diagram: the `pseudogapʹ controversy, metal–insulator transition and the anomalous transport. As we solve remaining obstacles we shall be able to tailor the electronic (and/or magnetic) properties of most layered oxides. New concepts and applications will emerge, yet for successful ambient nanelectronics of the 21st century we should first learn to artificially `constructʹ colossal layered superconductors with Tc≈450 K.